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A Population-based Survey of the Prevalence, Potential Risk Factors, and Symptom-specific Bother of Lower Urinary Tract Symptoms in Adult Chinese Women

  • Lei Zhang 1,
  • Lan Zhu 1,
  • Tao Xu 2,
  • Jinghe Lang 1,
  • Zhaoai Li 3,
  • Jian Gong 4,
  • Qing Liu 5,
  • Xiaochun Liu 6
1 Department of Gynecology and Obstetrics, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences; Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, People's Republic of China 2 Department of Epidemiology and Statistics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, People's Republic of China 3 Department of Gynecology and Obstetrics, Maternal and Child Health Hospital of Shanxi Province, Shanxi, People's Republic of China 4 Department of Gynecology and Obstetrics, Maternal and Child Health Hospital of Wuxi, Jiangsu, People's Republic of China 5 Department of Gynecology and Obstetrics, Gansu Provincial Maternity and Child-care Hospital, Lanzhou, Gansu Province, People's Republic of China 6 Department of Gynecology and Obstetrics, Maternal and Child Health Hospital of Foshan, Guangdong, People's Republic of China

Take home message

The prevalence of lower urinary tract symptoms (LUTS) is high and increases with age in adult women in China. Nocturia, urgency, and stress urinary incontinence were more prevalent. Urgency and urgency urinary incontinence were most frequently regarded as severe or moderate bothers. Multiple factors influenced LUTS.

PII: S0302-2838(14)01267-6

DOI: 10.1016/j.eururo.2014.12.012

Background

Epidemiological studies of lower urinary tract symptoms (LUTS) are few in China, and none has been conducted nationwide.

Objective

To estimate the prevalence and potential risk factors of LUTS and the bother they impose on adult women in China.

Design, setting, and participants

This is the second analysis of a population-based cross-sectional survey on urinary incontinence conducted between February and July 2006 in six regions of China. Cluster samples were randomly selected for interviews.

Interventions

No intervention was implemented.

Outcome measurements and statistical analysis

A modified Chinese Bristol Female Lower Urinary Tract Symptoms questionnaire was administered. The participants were asked about the presence of individual LUTS and rated their symptom bother. Descriptive statistics, χ2 tests, receiver operating characteristic curves, and multivariate logistic regressions were used for data analysis.

Results and limitations

A total of 18 992 respondents (94.96%) were included. The prevalence of any LUTS, storage symptoms, or voiding symptoms was 55.5%, 53.9%, and 12.9%, respectively, and increased with age. Nocturia was the most common symptom (23.4%), followed by urgency (23.3%) and stress urinary incontinence (SUI; 18.9%). Nocturia was most frequently rated as bothersome (93.0%) but was generally minor (80.5%). Urgency and urgency urinary incontinence (UUI) were most frequently reported as severe (11.5% and 10.8%) or moderate (18.5% and 16.8%) bothers. Any LUTS were more prevalent in urban women (57.1% vs 53.9%). Multiple factors increased the odds of bother and individual LUTS, and older age and coexisting pelvic organ prolapse were strong predictors (p < 0.05). This survey was conducted 8 yr ago and did not assess all LUTS.

Conclusions

Half of adult women suffered with LUTS; nocturia, urgency, and SUI were more prevalent. Urgency and UUI were most frequently reported as severe or moderate bothers. Multiple factors influenced bother and individual LUTS.

Patient summary

The prevalence of lower urinary tract symptoms is high and increases with age in adult women in China. Urgency and urgency urinary incontinence were most frequently regarded as severe or moderate bothers and should be targeted for medical intervention.

Lower urinary tract symptoms (LUTS) have attracted substantial attention in recent years partly because to their high prevalence but primarily because of heightened awareness of their detrimental impact on health-related quality of life [1] . Studies report that one in five adult women complain about moderate to severe LUTS, and one in ten adults have newly developed LUTS, often along with resulting substantial bother and interference with daily activities [2] and [3]. By 2018, an estimated 2.3 billion people will be affected by at least one LUTS. The prevalence of LUTS is likely to be greater in women than in men. The regional burden of these conditions is estimated to be greatest in Asia [1] . Many large-scale epidemiologic studies of LUTS have been conducted in Western countries, and prevalence estimates reported for LUTS subsets vary widely from 13% to 76% [4] and [5]. This variation could be due to differences in study populations, symptom assessment, data collection, or definitions used [3], [6], and [7]. In China, there have been relatively few epidemiologic studies of LUTS. Several studies have estimated the prevalence of LUTS in Asian countries such as Japan, Korea, and Taiwan [8], [9], and [10]; however, there are notable inconsistencies in the prevalence rates reported across studies, and few were conducted nationwide. In addition, many were limited by bias related to sex, specific LUTS, and age groups.

The aim of this study was to provide estimates of the prevalence and potential risk factors of LUTS and the bother they impose in a nationwide population-based sample of adult women in China.

2.1. Study design and participants

This analysis is the second of a previous study. The data were from a national cross-sectional survey on urinary incontinence (UI) in 20 000 adult women aged ≥20 yr in China. The previous survey included two phases: a pilot study conducted in Beijing, China [11] , and a subsequent nationwide study [12] and [13]. Detailed study procedures and results for stress urinary incontinence (SUI), urgency urinary incontinence (UUI), and mixed urinary incontinence (MUI) have been described in previous reports [11], [12], and [13].

Phase 1 (a pilot survey in Beijing) assessed a representative sample of approximately 5221 respondents (from one urban district and one rural district) who were interviewed face to face by trained interviewers using a standardized questionnaire. The eligibility criteria stipulated women aged ≥20 yr in the general population who had lived in the registered areas for at least 10 yr. We excluded women who were medically diagnosed with cognitive impairment and who could not understand the questions. Detailed study procedures and results were published [11] .

Phase 2 was a nationwide survey conducted between February and July 2006 in six regions of China. The sampling process was multistage and stratified according to geographic region (northwest, southwest, north, east, northeast, and central-south China) and degree of urbanization (large cities and undeveloped economic status were assessed on the basis of the gross domestic product for each province). Eligibility and exclusion criteria were in accord with the pilot survey (on the basis of Chinese population data from 2006). The rationale for the recruitment approach, the study design, and the interpretation of results has been described previously [12] and [13]. Ethics committee approval and written informed consent were obtained.

Our previous study focused on UI, so we recalculated the sample size for this reanalysis according to a previous study conducted in Fuzhou, China, which reported 39.7% prevalence of LUTS in female residents [14] . We aimed to survey at least six age deciles: 20–29, 30–39, 40–49, 50–59, 60–69, and ≥70 yr. A minimal sample size was calculated for detection of 39.7% prevalence of LUTS, with a 5% estimated error and a 95% confidence interval (CI). Considering a 20% refusal rate, a total of 16 805 participants would be required for the LUTS reanalysis according to the formula

FORMULA:

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The sample size was large enough for our reanalysis.

2.2. Diagnostic criteria

The definitions in this study are consistent with the standards recommended by the 2002 International Continence Society (ICS) guidelines [15] . Nocturia is a condition whereby a person awakens at night one or more times to void, and was defined as two or more micturitions per night in our study. Daytime frequency is a condition whereby a patient voids too often by day. In our study, frequency was defined as voiding eight times or more per day. Respondents who reported both UUI and SUI symptoms were classified as having MUI. Those who reported UI without symptoms of UUI or SUI were categorized as having other UI. Women who had given birth to multiple children were defined as having more than one delivery.

2.3. Measurements

We used a modified Bristol Female Lower Urinary Tract Symptoms questionnaire [16] that consisted of two parts. Part 1 included general information about age, marital status, occupation, menopausal status, medically diagnosed disease status, parity, mode of delivery for childbirth, and offspring birth weights. Part 2 was a Chinese version of the International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms (ICIQ-FLUTS). The Chinese version of the questionnaire was translated by survey research experts. To assess the accuracy of the translation, the Chinese version was translated back to English and compared by an independent agent. A pilot study of 40 women was performed before the survey took place to ensure the validity of the questionnaire. The readability of the Chinese version of the questionnaire was at the primary school level.

The questionnaire included an assessment of ten types of LUTS: nocturia, daytime frequency, urgency, UUI, SUI, other incontinence, pain or burning, hesitancy, straining, and intermittency. Participants were asked to rate how often individual LUTS were experienced during the previous 4 wk and, if LUTS were experienced, to what degree the symptoms were bothersome. All subjects reporting LUTS were asked to describe the frequency of the symptoms. Nocturia was measured as the number of micturitions per night, and frequency was defined as eight or more times per day. The other symptoms were measured according to how long participants had experienced them in the previous 4 wk, classified as: no (never); <10 d (occasionally); 10–20 d (sometimes); 20 d (most of the time); or every day (all of the time). The prevalence of other LUTS was defined as answers other than no. The bother associated with each symptom was evaluated using a scale ranging from 0 (not bothered at all) to 10 (greatly bothered). Bother was also defined by dividing the Likert responses into three groups: minor (rated 1–4), moderate (rated 5–7), and severe (rated 8–10). Detailed information on sociodemographic background, reproductive factors, defecation, and medical conditions was also collected. The interviewers underwent standardized training and regular quality control checks.

2.4. Statistical analysis

The data were finally stratified into eight age deciles. We performed χ2 tests to compare prevalence differences between groups. Receiver operating characteristic (ROC) curve distribution was used to assess the number of deliveries and their relationship to LUTS with moderate or severe bother. A multivariate model was set up to assess bother and individual LUTS-related potential risk factors and to estimate odds ratios and 95% CIs; this model was adapted for all factors in the final version. A two-sided p value ≤0.05 was considered for statistical significance. EpiData software ( http://www.epidata.dk/ ) was used for data entry and error detection. SPSS v.12.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis.

As shown in Figure 1 , 976 (4.88%) of the questionnaires could not be evaluated and were excluded in the previous UI study; 32 participants were further excluded because of missing information regarding reproductive factors or LUTS symptoms. A total of 18 992 participants (94.96%) were entered into our data analyses. The age distribution ranged from 20 to 99 yr, with a mean of 44.9 yr (±15.9 yr) (the age distribution in our study was similar to the total adult population in the 2006 National Census). Overall, 438 participants (2.3%) were from minority groups. The numbers of participants from urban and rural areas were equal (50% vs 50%). Table 1 lists the sociodemographic characteristics of the participants.

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Fig. 1 Study flowchart. UI = urinary incontinence; LUTS = lower urinary tract symptoms.

Table 1 Characteristics of the 18 992 subjects interviewed

Characteristic Data
Mean age, yr (SD) 44.91 (15.9)
Age, n (%)
 20–29 yr 3381 (17.8)
 30–39 yr 4778 (25.2)
 40–49 yr 4199 (22.1)
 50–59 yr 2881 (15.2)
 60–69 yr 2029 (10.7)
 70–79 yr 1194 (6.3)
 80–89 yr 442 (2.3)
 ≥90 yr 88 (0.5)
Residence, n (%)
 Urban 9490 (50.0)
 Rural 9502 (50.0)
Current marital status, n (%)
 Single, never married 1392 (7.3)
 Married 15 976 (84.1)
 Remarried 178 (0.9)
 Divorced/separated 77 (0.4)
 Widowed 1369 (7.2)
Mean body mass index, kg/m2 (SD) 23.4 (3.8)
Body mass index, n (%)
 Underweight (<18.5 kg/m2) 1140 (6.0)
 Normal (18.5–23.9 kg/m2) 10 370 (54.6)
 Overweight (24–27.9 kg/m2) 5480 (28.9)
 Obese (≥28 kg/m2) 2002 (10.5)
Median parity, pregnancies (range) 1 (0–10)
Parity, n (%)
 Nulliparous 2251 (11.9)
 Primiparous (=1) 8980 (47.3)
 Multiparous (=2) 4286 (22.6)
 Multiparous (≥3) 3475 (18.3)
Job, n (%)
 Manual labor 4343 (22.9)
 Intellectual labor 14 649 (77.1)
Race, n (%)
 Han 18 554 (97.7)
 Minority 438 (2.3)

3.1. Prevalence of LUTS

The frequencies of individual LUTS are shown in Table 2 . The prevalence of any LUTS was 55.5% and increased with age. Storage symptoms were more common than voiding symptoms (53.9% vs 12.9%). Nocturia was the most common symptom (23.4%), followed by urgency (23.3%) and SUI (18.9%); incontinence was also highly prevalent (31.9%). Straining was the least common symptom (3.3%; Table 2 ).

Table 2 Prevalence of individual lower urinary tract symptoms by age and residence

  Symptoms, n (%)
  Total Age group Residence
  (n = 18 992) 20–29 yr 30–39 yr 40–49 yr 50–59 yr 60–69 yr 70–79 yr 80–90 yr ≥90 yr p value b Urban Rural p value b
    (n = 3381) (n = 4778) (n = 4199) (n = 2881) (n = 2029) (n = 1194) (n = 442) (n = 88)   (n = 9490) (n = 9502)  
Nocturia
 ≥2 times/night 4450 (23.4) 302 (8.9) 542 (11.3) 745 (17.7) 900 (31.2) 891 (43.9) 715 (59.9) 289 (65.4) 66 (75.0) <0.001 2161 (22.8) 2289 (24.1) 0.032
Frequency 3290 (17.3) 438 (13.0) 654 (13.7) 666 (15.9) 583 (20.2) 454 (22.4) 329 (27.6) 133 (30.1) 33 (37.5) <0.001 1934 (20.4) 1356 (14.3) <0.001
Urgency 4430 (23.3) 399 (11.8) 774 (16.2) 966 (23.0) 847 (29.4) 655 (32.3) 503 (42.1) 237 (53.6) 49 (55.7) <0.001 2361 (24.9) 2069 (21.8) <0.001
UI
 Any UI 6052 (31.9) 362 (10.7) 948 (19.8) 1488 (35.4) 1316 (45.7) 990 (48.8) 643 (53.9) 247 (55.9) 58 (65.9) <0.001 2733 (28.8) 3319 (34.9) <0.001
 UUI 488 (2.6) 35 (1.0) 73 (1.5) 84 (2.0) 81 (2.8) 94 (4.6) 97 (8.1) 23 (5.2) 1 (1.1) <0.001 272 (2.9) 216 (2.3) 0.01
 SUI 3,592 (18.9) 178 (5.3) 659 (13.8) 993 (23.6) 812 (28.2) 556 (27.4) 286 (24.0) 85 (19.2) 23 (26.1) <0.001 1555 (16.4) 2037 (21.4) <0.001
 MUI 1,788 (9.4) 43 (1.3) 206 (4.3) 398 (9.5) 405 (14.1) 320 (15.8) 247 (20.7) 136 (30.8) 33 (37.5) <0.001 752 (7.9) 1036 (10.9) <0.001
Other UI 858 (4.5) 123 (3.6) 71 (1.5) 138 (3.3) 174 (6.0) 145 (7.1) 134 (11.2) 52 (11.8) 21 (23.9) <0.001 468 (4.9) 390 (4.1) 0.006
 Any involuntary a 536 (2.8) 13 (0.4) 50 (1.0) 95 (2.3) 110 (3.8) 100 (4.9) 102 (8.5) 45 (10.2) 21 (23.9) <0.001 235 (2.5) 301 (3.2) 0.004
 Nocturnal enuresis 172 (0.9) 10 (0.3) 12 (0.3) 27 (0.6) 30 (1.0) 25 (1.2) 40 (3.4) 19 (4.3) 9 (10.2) <0.001 105 (1.1) 67 (0.7) 0.004
 During intercourse a 336 (2.0) 110 (3.7) 30 (0.6) 53 (1.3) 72 (2.8) 42 (3.0) 27 (4.2) 2 (1.1) 0 <0.001 227 (2.7) 109 (1.3) <0.001
Pain/burning 854 (4.5) 71 (2.1) 175 (3.7) 208 (5.0) 167 (5.8) 130 (6.4) 65 (5.4) 29 (6.6) 9 (10.2) <0.001 374 (3.9) 480 (5.1) <0.001
Hesitancy 1072 (5.6) 137 (4.1) 171 (3.6) 167 (4.0) 200 (6.9) 155 (7.6) 152 (12.7) 71 (16.1) 19 (21.6) <0.001 675 (7.1) 397 (4.2) <0.001
Straining 626 (3.3) 39 (1.2) 87 (1.8) 117 (2.8) 110 (3.8) 110 (5.4) 101 (8.5) 44 (10.0) 18 (20.5) <0.001 378 (4.0) 248 (2.6) <0.001
Intermittency 1346 (7.1) 110 (3.3) 211 (4.4) 231 (5.5) 259 (9.0) 233 (11.5) 197 (16.5) 83 (18.8) 22 (25.0) <0.001 801 (8.4) 545 (5.7) <0.001
Storage symptoms 10 245 (53.9) 1117 (33.0) 1930 (40.4) 2299 (54.8) 1956 (67.9) 1500 (73.9) 987 (82.7) 375 (84.8) 81 (92.0) <0.001 5249 (55.3) 4996 (52.6) <0.001
Voiding symptoms 2444 (12.9) 249 (7.4) 452 (9.5) 475 (11.3) 461 (16.0) 393 (19.4) 271 (22.7) 113 (25.6) 30 (34.1) <0.001 1353 (14.3) 1091 (11.5) <0.001
Any LUTS 10 540 (55.5) 1185 (35.0) 2034 (42.6) 2360 (56.2) 1988 (69.0) 1521 (75.0) 992 (83.1) 378 (85.5) 82 (93.2) <0.001 5420 (57.1) 5120 (53.9) <0.001

a 16 695 women were sexually active and included in the category UI during sexual intercourse. The category Any involuntary represents women who reported leaking for no reason or any involuntary loss of urine.

b The Pearson χ2 test was used to compare differences in the prevalence of individual LUTS by age and residence.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence.

A notable age-related trend was observed for the prevalence of any LUTS, storage, or voiding symptoms, with approximately 50% greater prevalence observed for the oldest compared to the youngest participants ( Table 2 ; Fig 2 and Fig 3). UI was frequent in women aged ≤70 yr, but nocturia was more prevalent in those aged ≥70 yr. Urgency was usually reported by women aged ≤50 yr. Frequency, urgency, hesitancy, straining, and intermittency were more common in urban women (p < 0.001). Rural women experienced more nocturia (22.8% vs 24.1%; p = 0.032). UI was the most common symptom (28.8% vs 34.9%; p < 0.001) in both areas, but particularly in rural areas ( Fig. 3 ).

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Fig. 2 Age-specific prevalence of lower urinary tract symptom subtypes. UI = urinary incontinence.

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Fig. 3 Urban and rural prevalence differences for individual lower urinary tract symptoms. UI = urinary incontinence.

3.2. Symptom-specific bother of LUTS

The extent to which study participants were bothered by each urinary symptom is summarized in Table 3 and Fig. 4 . We found that no bother or minor bother were the most common responses reported for every symptom. Only 14.6–29.9% of participants with bothersome LUTS reported a moderate to severe impact on their quality of life; 4.2–11.5% reported severe bother. Some of the most prevalent symptoms were among those least commonly reported as bothersome, such as SUI (67.4%). Some of the most likely to be rated as bothersome were not necessarily the most likely to cause moderate or severe bother, such as nocturia (19.5%). Urgency was among the least likely to cause bother but was the symptom most likely to cause severe (11.5%) or moderate to severe bother (29.9%), followed by UUI (10.8% and 27.6%, respectively). Frequency was the storage symptom that was least commonly reported as causing moderate or severe bother (14.6%).

Table 3 Self-reported bother related to individual lower urinary tract symptoms

Bother Symptoms, n (%)
  Nocturia Frequency Urgency UUI a SUI Pain/burning Hesitancy Straining Intermittency
Likert score
 0 14 854 (78.21) 17 090 (89.99) 16 242 (85.52) 17 245 (90.80) 15 366 (80.91) 18 270 (96.20) 18 333 (96.53) 18 527 (97.55) 18 136 (95.49)
 1 1505 (7.92) 818 (4.31) 771 (4.06) 534 (2.81) 1302 (6.86) 285 (1.50) 271 (1.43) 156 (0.82) 284 (1.50)
 2 879 (4.63) 426 (2.24) 553 (2.91) 329 (1.73) 868 (4.57) 173 (0.91) 140 (0.74) 114 (0.60) 200 (1.05)
 3 625 (3.29) 271 (1.43) 403 (2.12) 277 (1.46) 540 (2.84) 97 (0.51) 100 (0.53) 64 (0.34) 136 (0.72)
 4 322 (1.70) 110 (0.58) 200 (1.05) 126 (0.66) 269 (1.42) 56 (0.29) 46 (0.24) 32 (0.17) 75 (0.39)
 5 284 (1.50) 94 (0.49) 256 (1.35) 149 (0.78) 247 (1.30) 47 (0.25) 34 (0.18) 34 (0.18) 58 (0.31)
 6 141 (0.74) 67 (0.35) 149 (0.78) 97 (0.51) 108 (0.57) 16 (0.08) 24 (0.13) 24 (0.13) 35 (0.18)
 7 133 (0.70) 36 (0.19) 103 (0.54) 46 (0.24) 80 (0.42) 11 (0.06) 12 (0.06) 7 (0.04) 17 (0.09)
 8 137 (0.72) 41 (0.22) 147 (0.77) 86 (0.45) 85 (0.45) 20 (0.11) 12 (0.06) 16 (0.08) 25 (0.13)
 9 112 (0.59) 39 (0.21) 168 (0.88) 103 (0.54) 127 (0.67) 17 (0.09) 20 (0.11) 18 (0.09) 26 (0.14)
 10 0 0 0 0 0 0 0 0 0
Any bother b 4138 1902 2750 1747 3626 722 659 465 856
Moderate to severe bother 807 (19.50) 277 (14.56) 823 (29.93) 483 (27.60) 647 (17.84) 111 (15.37) 102 (15.48) 99 (21.29) 161 (18.81)
Any severe bother 249 (6.02) 80 (4.21) 315 (11.45) 189 (10.80) 212 (5.85) 37 (5.12) 32 (4.86) 34 (7.31) 51 (5.96)
Any LUTS 4450 3290 4430 2276 5380 854 1072 626 1346
Bother rate (%) 92.99 57.81 62.08 76.78 67.40 84.54 61.47 74.28 63.60

a SUI and UUI include participants with mixed urinary incontinence.

b Any bother: participants reported that they were bothered by at least one individual LUTS.

UUI = urgency urinary incontinence; SUI = stress urinary incontinence; LUTS = lower urinary tract symptoms.

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Fig. 4 Symptom-specific bother and extent of individual lower urinary tract symptoms. Bother was also defined by dividing the Likert responses into three groups: (a) 1–4, minor; (b) 5–7, moderate; and (c) 8–10, severe. UUI = urgency urinary incontinence; SUI = stress urinary incontinence.

Voiding symptoms were less likely to cause moderate or severe bother than storage symptoms (p < 0.001). Pain or burning was the second most frequent bother (84.5%), but straining and intermittency were more likely to cause moderate or severe bother (21.3% and 18.8%, respectively; Table 3 ).

3.3. Potential risk factors for LUTS

Risk factors for LUTS according to logistic regression analysis are shown in Table 4, Table 5, and Table 6. We identified multiple risk factors for any, individual, and bothersome LUTS; older age, postmenopausal status, constipation, and coexisting pelvic organ prolapse (POP) increased the odds for every type of LUTS. Older age and coexisting POP were both strong predictors (p ≤ 0.05). In comparison with spontaneous vaginal single births, our study showed a higher risk of storage and moderate or severe bothersome LUTS in women with multiple vaginal deliveries (1.46-fold and 1.26-fold, respectively) and instrumental deliveries (1.25-fold and 1.22-fold, respectively). ROC distributions showed that multiple deliveries were more closely related to any severely bothersome LUTS ( Fig. 5 ). Women who had single or multiple deliveries via cesarean section had no increase in odds for every LUTS (p > 0.05), as did women who had spontaneous vaginal single births. Participants with histories of prolonged labor and perineal laceration had increased odds for moderate or severe bothersome LUTS; prolonged labor may have a stronger influence (1.99-fold, with adjustment for all other factors). Voiding symptoms were less influenced by delivery histories. Lifestyle factors and pathologic conditions such as higher body mass index (BMI), hypertension, diabetes, alcohol consumption, and smoking had various effects on any, individual, and bothersome LUTS (Table 4, Table 5, and Table 6).

Table 4 Multivariate analyses of associations between patient characteristics and bothersome lower urinary tract symptoms

  n (%) Any LUTS bother (n = 6950) Moderate to severe LUTS bother (n = 1695) Any severe LUTS bother (n = 652)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted OR a 95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) <0.001 1.43 1.26, 1.63 0.078 1.29 0.97, 1.71 0.072 1.63 0.96, 2.79
 40–49 yr 4199 (22.1) <0.001 1.85 1.62, 2.12 <0.001 2.04 1.54, 2.69 <0.001 2.91 1.73, 4.90
 50–59 yr 2881 (15.2) <0.001 2.08 1.75, 2.47 <0.001 2.71 1.96, 3.74 <0.001 4.99 2.83, 8.80
 60–69 yr 2029 (10.7) <0.001 2.12 1.73, 2.60 <0.001 2.29 1.60, 3.28 <0.001 4.45 2.41, 8.20
 70–79 yr 1194 (6.3) <0.001 2.75 2.21, 3.43 <0.001 2.70 1.86, 3.91 <0.001 5.16 2.77, 9.64
 80–89 442 (2.3) <0.001 3.59 2.74, 4.71 <0.001 3.58 2.39, 5.37 <0.001 6.59 3.40, 12.78
  ≥90 yr 88 (0.5) <0.001 9.24 5.19, 16.47 <0.001 7.30 4.18, 12.77 <0.001 16.56 7.59, 36.10
Residence   <0.001     0.109     0.846    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.16 1.08, 1.24   1.10 0.98, 1.23   1.02 0.86, 1.21
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.66 1.49, 1.86 <0.001 1.79 1.48, 2.15 <0.001 2.26 1.68, 3.02
 Postmenopausal status 6178 (32.5) <0.001 1.55 1.35, 1.77 <0.001 1.55 1.25, 1.92 0.016 1.51 1.08, 2.12
Body mass index   <0.001     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.425 1.06 0.91, 1.24 0.008 1.41 1.09, 1.81 0.844 0.96 0.60, 1.51
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.16 1.08, 1.25 <0.001 1.29 1.15, 1.46 0.001 1.38 1.14, 1.66
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.47 1.27, 1.71 <0.001 1.70 1.37, 2.10 <0.001 1.81 1.33, 2.48
Mode of delivery   <0.001     0.001     0.006    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.25 1.14, 1.36 0.002 1.26 1.09, 1.46 0.001 1.51 1.20, 1.92
 Forceps or vacuum delivery 746 (3.9) 0.026 1.20 1.02, 1.42 0.134 1.22 0.94, 1.58 0.240 1.29 0.85, 1.96
 Cesarean section                    
  1 2,399 (12.6) 0.001 0.83 0.75, 0.93 0.095 0.83 0.67, 1.03 0.502 0.87 0.59, 1.30
  ≥2 55 (3.0) 0.965 1.01 0.58, 1.77 0.401 1.42 0.63, 3.23 0.356 1.76 0.53, 5.83
 Nulliparity 2251 (11.9) <0.001 0.64 0.55, 0.74 0.050 0.74 0.54, 1.00 0.090 1.50 0.94, 2.41
Prolonged labor b   <0.001     <0.001     <0.001    
 No (ref.) 13 444 (95.7)   1.00     1.00     1.00  
 Yes 599 (4.3)   1.62 1.35, 1.94   1.99 1.58, 2.50   2.19 1.58, 3.02
Perineal laceration b   <0.001     0.018     0.700    
 No (ref.) 10 312 (77.0)   1.00 -   1.00     1.00  
 Yes 3088 (23.0)   1.22 1.12, 1.33   1.17 1.03, 1.34   1.04 0.85, 1.04
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.97 1.79, 2.16   2.22 1.95, 2.52   2.28 1.89, 2.76
Hormone replacement therapy   0.009     0.510     0.879    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.69 0.52, 0.91   1.17 0.74, 1.84   0.95 0.50, 1.82
Pelvic organ prolapse   <0.001     <0.001     0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.08 1.55, 2.77   2.29 1.65, 3.18   2.12 1.35, 3.35
Hypertension   <0.001     <0.001     0.017    
 Nonexistent (ref.) 17 093 (90.0)   1.00 -   1.00     1.00  
 Present 1899 (10.0)   1.48 1.33, 1.65   1.49 1.29, 1.72   1.29 1.05, 1.60
Diabetes   0.001     0.001     0.011    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.38 1.14, 1.67   1.48 1.18, 1.86   1.52 1.10, 2.10
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.25 1.11, 1.39   1.54 1.28, 1.85   2.10 1.56, 2.78
Alcohol consumption   <0.001     0.466     0.168    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.37 1.23, 1.52   1.07 0.90, 1.27   1.20 0.93, 1.56

a The adjusted odds ratios with 95% confidence intervals are presented. All of the factors, except for prolonged labor and perineal laceration, were adjusted in the multivariate model. For prolonged labor and perineal laceration, the other factors were adjusted. Pelvic organ prolapse, hypertension, and diabetes were defined according to hospital diagnosis.

b There were some missing data for prolonged labor (244) and perineal laceration (887) because the participants could not accurately recall these histories.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 5 Multivariate analyses of associations between patient characteristics and the presence of storage, voiding, and incontinence lower urinary tract symptoms

  n (%) Storage symptoms (n = 10 245) Voiding symptoms (n = 2444) Any urinary incontinence (n = 6052)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.001 1.21 1.09, 1.36 0.001 1.38 1.14, 1.67 <0.001 1.55 1.34, 1.80
 40–49 yr 4199 (22.1) <0.001 1.75 1.56, 1.98 0.001 1.42 1.16, 1.74 <0.001 2.66 2.29, 3.10
 50–59 yr 2881 (15.2) <0.001 2.00 1.70, 2.36 <0.001 1.57 1.22, 2.01 <0.001 2.80 2.32, 3.38
 60–69 yr 2029 (10.7) <0.001 2.01 1.64, 2.47 0.001 1.63 1.22, 2.18 <0.001 2.46 1.98, 3.06
 70–79 yr 1194 (6.3) <0.001 3.30 2.61, 4.17 <0.001 1.84 1.36, 2.48 <0.001 3.02 2.39, 3.81
 80–89 442 (2.3) <0.001 3.93 2.86, 5.39 <0.001 2.03 1.44, 2.86 <0.001 3.32 2.52, 4.37
 ≥90 yr 88 (0.5) <0.001 9.14 4.11, 20.29 <0.001 2.98 1.75, 5.05 <0.001 5.87 3.58, 9.65
Residence   <0.001     <0.001     0.006    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.35 1.26, 1.45   1.32 1.19, 1.45   0.90 0.84, 0.97
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.55 1.39, 1.73 <0.001 1.75 1.50, 2.05 <0.001 1.61 1.43, 1.81
 Postmenopausal status 6178 (32.5) <0.001 1.63 1.42, 1.87 <0.001 1.50 1.24, 1.82 <0.001 1.44 1.26, 1.65
Body mass index   <0.001     0.204     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.445 1.05 0.92, 1.21 0.138 0.85 0.68, 1.06 0.137 0.88 0.74, 1.04
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.31 1.23, 1.41 0.839 0.99 0.90, 1.09 <0.001 1.34 1.25, 1.45
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.87 1.59, 2.21 0.180 1.14 0.94, 1.39 <0.001 1.77 1.52, 2.06
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.46 1.34, 1.60 <0.001 1.31 1.15, 1.49 <0.001 1.63 1.49, 1.79
 Forceps or vacuum delivery 746 (3.9) 0.007 1.25 1.06, 1.48 0.002 1.41 1.14, 1.75 <0.001 1.35 1.14, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.044 0.90 0.82, 1.00 0.590 0.96 0.81, 1.12 <0.001 0.72 0.63, 0.81
  ≥2 55 (3.0) 0.234 0.71 0.41, 1.25 0.513 1.30 0.60, 2.83 0.247 0.69 0.37, 1.29
 Nulliparity 2251 (11.9) 0.042 0.88 0.77, 1.00 0.293 1.12 0.91, 1.37 <0.001 0.71 0.59, 0.84
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.77 1.60, 1.95   2.18 1.95, 2.43   1.87 1.70, 2.06
Hormone replacement therapy   0.050     0.001     0.211    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.75 0.56, 1.00   0.58 0.41, 0.81   0.83 0.63, 1.11
Pelvic organ prolapse   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.38 1.68, 3.36   2.35 1.72, 3.21   1.96 1.47, 2.60
Hypertension   <0.001     0.202     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.41 1.24, 1.61   1.09 0.95, 1.25   1.29 1.16, 1.44
Diabetes   0.001     <0.001     0.114    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.49 1.17, 1.89   1.61 1.31, 1.99   1.17 0.96, 1.41
Smoking   <0.001     <0.001     0.306    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.31 1.17, 1.46   1.70 1.46, 1.98   1.06 0.95, 1.20
Alcohol consumption   <0.001     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.22 1.10, 1.35   1.37 1.18, 1.59   1.51 1.35, 1.68

a All of the factors were adjusted.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 6 Multivariate analyses of the association between patient characteristics and individual LUTS and any LUTS with adjustment for all factors

  n (%) Nocturia (n = 4450) Frequency (n = 3290) Urgency (n = 4430)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.598 0.96 0.81, 1.13 0.013 1.22 1.04, 1.42 <0.001 1.56 1.33, 1.82
 40–49 yr 4199 (22.1) 0.002 1.30 1.10, 1.54 <0.001 1.44 1.22, 1.70 <0.001 2.07 1.76, 2.43
 50–59 yr 2881 (15.2) <0.001 1.84 1.50, 2.26 <0.001 1.58 1.27, 1.95 <0.001 2.20 1.80, 2.69
 60–69 yr 2029 (10.7) <0.001 2.63 2.08, 3.32 <0.001 1.72 1.34, 2.21 <0.001 2.05 1.62, 2.60
 70–79 yr 1194 (6.3) <0.001 5.13 4.00, 6.57 <0.001 2.26 1.74, 2.94 <0.001 3.03 2.37, 3.88
 80–89 442 (2.3) <0.001 7.08 5.29, 9.48 <0.001 2.59 1.91, 3.52 <0.001 4.66 3.49, 6.21
 ≥90 yr 88 (0.5) <0.001 12.95 7.60, 22.06 <0.001 3.47 2.13, 5.67 <0.001 5.19 3.19, 8.45
Residence   0.692     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   0.98 0.91, 1.07   1.45 1.33, 1.58   1.29 1.19, 1.39
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.43 1.25, 1.64 <0.001 1.42 1.24, 1.63 <0.001 1.41 1.24, 1.61
 Postmenopausal status 6178 (32.5) <0.001 1.57 1.35, 1.83 <0.001 1.52 1.28, 1.81 <0.001 1.35 1.16, 1.57
Body mass index   <0.001     0.055     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.133 1.15 0.96, 1.39 0.611 1.05 0.88, 1.24 0.844 1.02 0.85, 1.12
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.46 1.35, 1.59 0.392 1.04 0.95, 1.13 <0.001 1.24 1.14, 1.34
 Obese (≥28 g/m2) 2002 (10.5) <0.001 2.16 1.84, 2.54 0.006 1.28 1.07, 1.53 <0.001 1.56 1.33, 1.83
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.037 1.12 1.01, 1.24 0.002 0.83 0.74, 0.93 0.000 1.41 1.27, 1.57
 Forceps or vacuum delivery 746 (3.9) 0.685 1.04 0.86, 1.26 0.372 1.09 0.90, 1.33 0.002 1.34 1.11, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.707 0.97 0.85, 1.12 0.212 1.09 0.95, 1.24 0.132 1.10 0.97, 1.25
  ≥2 55 (3.0) 0.600 1.18 0.63, 2.20 0.247 0.62 0.28, 1.39 0.567 0.81 0.40, 1.66
 Nulliparity 2251 (11.9) <0.001 0.59 0.49, 0.72 0.004 1.28 1.08, 1.51 0.020 1.22 1.03, 1.44
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.52 1.37, 1.69   1.26 1.13, 1.40   1.84 1.66, 2.02
Hormone replacement therapy   0.039     0.388     0.009    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.73 0.54, 0.98   1.17 0.82, 1.66   0.67 0.50, 0.91
Pelvic organ prolapse   0.002     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   1.62 1.20, 2.17   1.78 1.32, 2.41   2.00 1.51, 2.67
Hypertension   <0.001     0.075     0.112    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.48 1.32, 1.65   1.12 0.99, 1.27   1.10 0.98, 1.23
Diabetes   <0.001     0.084     0.049    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.73 1.42, 2.10   1.20 0.98, 1.48   1.21 1.00, 1.47
Smoking   0.047     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.15 1.00, 1.33   0.59 0.52, 0.68   2.20 1.94, 2.49
Alcohol consumption   0.004     0.133     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   0.82 0.72, 0.94   1.10 0.97, 1.24   1.29 1.14, 1.45
  n (%) UUI (n = 488) SUI (n = 3592) MUI (n = 1788)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.017 1.77 1.11, 2.83 <0.001 1.78 1.47, 2.15 <0.001 2.28 1.59, 3.26
 40–49 yr 4199 (22.1) 0.003 2.08 1.28, 3.38 <0.001 2.74 2.26, 3.31 <0.001 4.09 2.88, 5.82
 50–59 yr 2881 (15.2) 0.022 1.99 1.10, 3.58 <0.001 2.62 2.09, 3.29 <0.001 4.94 3.36, 7.26
 60–69 yr 2029 (10.7) 0.001 2.83 1.49, 5.38 <0.001 2.21 1.71, 2.86 <0.001 4.57 3.01, 6.93
 70–79 yr 1194 (6.3) 0.000 5.03 2.64, 9.57 <0.001 1.87 1.42, 2.46 <0.001 6.40 4.18, 9.79
 80–89 442 (2.3) 0.003 3.00 1.45, 6.24 0.040 1.43 1.02, 2.00 <0.001 11.15 7.13, 17.44
 ≥90 yr 88 (0.5) 0.624 0.60 0.08 4.68 0.001 2.41 1.41, 4.14 <0.001 17.01 9.34, 30.95
Residence   0.022     0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.26 1.03, 1.53   0.87 0.80, 0.95   0.81 0.72, 0.90
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.89 1.34, 2.67 <0.001 1.37 1.20, 1.57 <0.001 1.69 1.40, 2.03
 Postmenopausal status 6178 (32.5) 0.004 1.86 1.22, 2.84 <0.001 1.33 1.15, 1.55 0.077 1.21 0.98, 1.49
Body mass index   0.454     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.706 1.09 0.70, 1.69 0.39 0.91 0.73, 1.13 0.001 0.56 0.40, 0.79
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.214 1.14 0.93, 1.40 <0.001 1.35 1.24, 1.47 0.058 1.12 1.00, 1.26
 Obese (≥28 g/m2) 2002 (10.5) 0.157 1.31 0.90, 1.91 <0.001 1.42 1.20, 1.68 <0.001 1.60 1.31, 1.96
Mode of delivery   0.182     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.176 1.21 0.92, 1.60 <0.001 1.25 1.12, 1.38 <0.001 1.85 1.60, 2.15
 Forceps or vacuum delivery 746 (3.9) 0.801 0.94 0.56, 1.57 0.007 1.28 1.07, 1.54 0.014 1.39 1.07, 1.81
 Cesarean section                    
  1 2,399 (12.6) 0.045 1.42 1.01, 2.01 <0.001 0.66 0.57, 0.77 0.257 0.88 0.70, 1.10
  ≥2 55 (3.0) 0.997 * * 0.544 0.81 0.40, 1.62 0.843 0.90 0.32, 2.55
 Nulliparity 2251 (11.9) 0.040 1.61 1.02, 2.54 <0.001 0.34 0.26, 0.44 0.004 0.56 0.38, 0.83
Constipation   0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.49 1.18, 1.88   1.28 1.15, 1.42   2.15 1.89, 2.45
Hormone replacement therapy   0.075     0.883     0.143    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.57 0.30, 1.06   1.03 0.74, 1.42   0.74 0.50, 1.11
Pelvic organ prolapse   0.001     0.050     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.40 1.41, 4.06   1.36 1.01, 1.86   2.31 1.66, 3.21
Hypertension   0.390     0.004     0.067    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.12 0.87, 1.44   1.19 1.06, 1.34   1.14 0.99, 1.32
Diabetes   0.564     0.030     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.12 0.76, 1.67   0.79 0.64, 0.98   1.54 1.23, 1.93
Smoking   0.755     0.084     0.927    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.05 0.76, 1.47   1.13 0.98, 1.29   1.01 0.84, 1.21
Alcohol consumption   0.906     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.02 0.75, 1.02   1.34 1.18, 1.52   1.54 1.30, 1.83
  n (%) Other UI (n = 858) Pain/burning (n = 854) Hesitancy (n = 1072)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     0.016     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.007 0.63 0.45, 0.88 0.010 1.52 1.11, 2.09 0.912 1.02 0.78, 1.33
 40–49 yr 4199 (22.1) 0.108 1.31 0.94, 1.81 0.001 1.75 1.26, 2.43 0.898 0.98 0.74, 1.31
 50–59 yr 2881 (15.2) 0.003 1.82 1.22, 2.72 0.015 1.65 1.10, 2.45 0.136 1.31 0.92, 1.87
 60–69 yr 2029 (10.7) 0.008 1.84 1.17, 2.89 0.062 1.55 0.98, 2.45 0.334 1.23 0.81, 1.86
 70–79 yr 1194 (6.3) <0.001 2.85 1.81, 4.51 0.503 1.19 0.72, 1.95 0.002 1.95 1.28, 2.98
 80–89 442 (2.3) <0.001 2.88 1.74, 4.76 0.317 1.34 0.76, 2.37 <0.001 2.43 1.53, 3.85
 ≥90 yr 88 (0.5) <0.001 6.18 3.26, 11.72 0.089 2.04 0.90, 4.64 <0.001 3.25 1.70, 6.21
Residence   0.143     0.021     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.12 0.96, 1.30   0.83 0.71, 0.97   1.64 1.42, 1.89
Menstrual condition   0.007     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) 0.010 1.43 1.09, 1.89 <0.001 1.90 1.51, 2.39 <0.001 1.72 1.36, 2.18
 Postmenopausal status 6178 (32.5) 0.010 1.51 1.11, 2.06 0.042 1.35 1.01, 1.81 0.002 1.57 1.18, 2.08
Body mass index   0.298     0.643     0.537    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.300 1.18 0.87, 1.60 0.555 0.89 0.62, 1.30 0.187 0.81 0.59, 1.11
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.079 1.16 0.98, 1.36 0.218 0.91 0.78, 1.06 0.701 0.97 0.84, 1.12
 Obese (≥28 g/m2) 2002 (10.5) 0.312 1.17 0.86, 1.59 0.796 0.96 0.70, 1.31 0.669 1.06 0.81, 1.40
Mode of delivery   <0.001     <0.001     0.086    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.213 1.15 0.93, 1.42 <0.001 1.59 1.30, 1.94 0.785 1.03 0.85, 1.25
 Forceps or vacuum delivery 746 (3.9) 0.657 1.09 0.75, 1.60 0.030 1.47 1.04, 2.07 0.024 1.40 1.05, 1.88
 Cesarean section                    
  1 2399 (12.6) 0.654 0.93 0.68, 1.27 0.104 1.23 0.96, 1.57 0.373 0.90 0.71, 1.14
  ≥2 55 (3.0) 0.681 1.28 0.39, 4.20 0.230 1.90 0.67, 5.40 0.555 0.65 0.15, 2.75
 Nulliparity 2251 (11.9) <0.001 2.40 1.77, 3.26 0.184 0.77 0.53, 1.13 0.170 1.21 0.92, 1.60
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.87 1.57, 2.22   2.18 1.84, 2.57   2.11 1.82, 2.45
Hormone replacement therapy   0.859     0.497     0.071    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   1.06 0.57, 1.97   1.27 0.64, 2.50   0.65 0.40, 1.04
Pelvic organ prolapse   <0.001     0.026     0.012    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.65 1.76, 4.00   1.74 1.07, 2.84   1.81 1.14, 2.88
Hypertension   0.206     0.284     0.022    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.14 0.93, 1.39   0.89 0.71, 1.11   1.24 1.03, 1.48
Diabetes   0.017     0.041     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.44 1.07, 1.93   1.41 1.01, 1.95   1.61 1.24, 2.10
Smoking   0.267     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.16 0.90, 1.50   2.16 1.68, 2.78   1.70 1.70, 2.65
Alcohol consumption   0.846     0.119     0.013    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.03 0.80, 1.31   1.22 0.95, 1.56   1.33 1.06, 1.66
  n (%) Straining (n = 626) Intermittency (n = 1346) Any LUTS (n = 10 540)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.006 1.84 1.19, 2.84 0.003 1.51 1.15, 1.99 <0.001 1.22 1.09, 1.36
 40–49 yr 4199 (22.1) <0.001 2.45 1.57, 3.81 0.001 1.65 1.24, 2.20 <0.001 1.71 1.51, 1.92
 50–59 yr 2881 (15.2) <0.001 2.64 1.57, 4.43 <0.001 2.08 1.48, 2.92 <0.001 1.91 1.62, 2.25
 60–69 yr 2029 (10.7) <0.001 3.29 1.85, 5.85 <0.001 2.27 1.54, 3.34 <0.001 1.92 1.56, 2.35
 70–79 yr 1194 (6.3) <0.001 4.72 2.63, 8.47 <0.001 3.22 2.17, 4.78 <0.001 3.05 2.41, 3.86
 80–89 442 (2.3) <0.001 5.31 2.84, 9.93 <0.001 3.66 2.37, 5.63 <0.001 3.71 2.69, 5.12
 ≥90 yr 88 (0.5) <0.001 11.61 5.45, 24.73 <0.001 5.05 2.75, 9.28 <0.001 9.63 4.10, 22.61
Residence   <0.001     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.44 1.20, 1.73   1.49 1.31, 1.69   1.37 1.28, 1.47
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.92 1.42, 2.60 <0.001 1.64 1.33, 2.04 <0.001 1.62 1.45, 1.81
 Postmenopausal status 6178 (32.5) 0.062 1.41 0.98, 2.03 0.002 1.49 1.16, 1.92 <0.001 1.68 1.46, 1.93
Body mass index   0.778     0.378     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.350 0.81 0.52, 1.26 0.147 0.80 0.59, 1.08 0.461 1.05 0.92, 1.20
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.860 0.98 0.82, 1.18 0.492 1.05 0.92, 1.19 <0.001 1.29 1.21, 1.38
 Obese (≥28 g/m2) 2002 (10.5) 0.731 1.10 0.75, 1.50 0.747 1.04 0.81, 1.34 <0.001 1.80 1.52, 2.13
Mode of delivery   0.391     0.196     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.340 1.13 0.88, 1.44 0.097 1.16 0.97, 1.37 <0.001 1.45 1.32, 1.58
 Forceps or vacuum delivery 746 (3.9) 0.136 1.34 0.91, 1.96 0.058 1.31 0.99, 1.72 0.002 1.29 1.10, 1.53
 Cesarean section                    
  1 2399 (12.6) 0.522 0.90 0.65, 1.24 0.824 0.98 0.79, 1.21 0.047 0.90 0.82, 1.00
  ≥2 55 (3.0) 0.575 0.56 0.08, 4.19 0.847 1.11 0.39, 3.16 0.387 0.78 0.45, 1.37
 Nulliparity 2251 (11.9) 0.241 1.27 0.85, 1.91 0.118 1.25 0.95, 1.64 0.031 0.87 0.77, 0.99
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   2.60 2.16, 3.11   2.00 1.74, 2.30   1.87 1.69, 2.06
Hormone replacement therapy   0.021     0.008     0.040    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.53 0.30, 0.91   0.58 0.38, 0.87   0.73 0.55, 0.99
Pelvic organ prolapse   0.004     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.17 1.29, 3.65   2.65 1.85, 3.80   2.37 1.67, 3.37
Hypertension   0.278     0.004     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.13 0.91, 1.42   1.27 1.08, 1.49   1.41 1.24, 1.61
Diabetes   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.81 1.33, 2.45   1.63 1.29, 2.08   1.60 1.25, 2.06
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.97 1.47, 2.63   1.46 1.20, 1.78   1.32 1.18, 1.48
Alcohol consumption   0.036     0.006     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.36 1.02, 1.82   1.31 1.08, 1.59   1.24 1.12, 1.38

* The sample was small, so the 95% CI could not be calculated.

OR c = odds ratio; CI = confidence interval; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence; LUTS = lower urinary tract symptoms.

gr5

Fig. 5 Receiver operating characteristic curve analysis for the relationship between number of deliveries and moderately or severely bothersome lower urinary tract symptoms (LUTS). (A) Moderately to severely bothersome LUTS in relation to number of deliveries. Area = 0.653; 95% confidence interval 0.639–0.667. When n = 2(1.5), the sensitivity is 63.1% and the specificity is 61.3%. (B) Any severely bothersome LUTS in relation to the number of deliveries. Area = 0.689; 95% confidence interval 0.666–0.711. When n = 2(1.5), the sensitivity is 70.0% and the specificity is 60.1%.

We conducted a PubMed search for English-language articles focused on epidemiology and bother of LUTS ( Table 7 ). The prevalence of any LUTS in our study was higher (55.5%) than in the large population-based EPIC study with an original five-nation European and North American survey (48.1%) [7] but lower than in an Internet-based study in the USA, the UK, and Sweden (76.3%) [5] and population-based studies in Brazil (84.1%) [6] , Russia, the Czech Republic, and Turkey (81–87%) [17] . The prevalence of any LUTS was lower than that in Korea (68.9%) [18] . In China, prevalence varies between studies. Hong Kong and Taiwan showed higher prevalence (74%) [19] , but a previous study in Fuzhou, China, identified an even lower rate (39.7%) [14] .

Table 7 Overview of published English-language population-based studies on the epidemiology and bother of lower urinary tract symptoms *

Study Countries/

Year conducted
Total no.

(women, n, %)
Response rate (%) Age (yr) Definition;

questionnaire
Numbers of LUTS

evaluated
Prevalence of any or individual LUTS in women (%) Moderate to severe bother (women %) Race Methods
Irwin et al 2006 [7] Canada; Germany;

Italy; Sweden; UK

2005
19 165

(N/A)
33 ≥18 2002 ICS;

Self-designed
18 Any: 66.6% a or 48.1% b ;

Nocturia: 54.5% a or 24.0% b ;

Storage: 59.2% a ; Voiding: 19.5%;

Urgency:12.8%; UI: 13.1%; SUI:6.4%;

Terminal dribble: 9.9%
N/A Predominantly white Computer-assisted telephone
Coyne et al 2009 [5] USA;

UK;

Sweden;

2007–2008
30 000

(15 861, 52.9%)

USA 20 000;

UK 7500;

Sweden 2500
59.6;

60.6;

52.3
40–99 2002 ICS;

self-designed;

questions according to ICS

definition
20 c Any: 76.3% (sometimes) or 52.5% (often);

Nocturia: 75.8% a or 33.7% b ;

Terminal dribble: 38.3%; Urgency: 35.7%;

Frequency: 24.6%;

SUI: 31.8%; UUI: 24.4%
Somewhat bothered:

Urgency: 74.7%;

SUI: 74%;

Dysuria: 73.5%

UUI: 71.3%
White; Black; Hispanic; Asian/other Internet-based
Koga et al 2014 [17] Russia;

Czech Republic;

Turkey;

2010
3130

(1614, 51.6%)
N/A ≥18 ICS;

European EPIC questionnaire
18 Any: 81%; 83%; 87% a ;

Storage: 74%, 73%, 81%;

Voiding: 41%, 32, 38%;

Postmicturition: 20%, 26%, 21%;

UI: 20%
Frequency: 58%;

Nocturia: 54%
N/A Computer-assisted telephone and face-to-face
Moreira et al 2013 [6] Brazil;

2006–2007
3000

(1500, 50.0%)
83 ≥30 2002 ICS;

Self-designed
18 c Any: 84.1% a

Storage: 76.4%; Voiding: 33.7%;

Postmicturition: 12.8%;

Nocturia: 71.2% a and 36.5% b ;

Frequency: 23.7%; Urgency: 10.0%;

UI: 5.8%; Terminal dribble: 13.0%
Any bother:

Urgency: 75%,

Nocturia: ≤50%
White; Black;

Mixed; Other
Interviewer-

administered
Coyne et al 2013 [21] USA;

2010
10 000

(5023, 50.2%)
56.7 18–70 ICS;

self-designed;

questions according to ICS

definition
11 c Any: N/A

Terminal dribble: 33.4%;

Nocturia: 27.8% b , c

Urgency: 24.4% c ; UUI: 18.5% c ;

Incomplete emptying: 20.9%**
N/A African-Americans; Hispanics; Whites Internet-based
Boyle et al 2003 [4] Netherlands;

France; UK; Korea;

N/A
8769

(3790, 43.2%)
N/A 40–79 I-PSS ≥ 8 7 c 18.0%; 12.6%; 23.7%; 19.9% 8 ≤ I-PSS ≤ 20: 11.0–19.5%;

20 ≤ I-PSS ≤ 35: 1.6–4.2%
N/A Self-completed

postal and direct
Kupelian et al 2006 [2] USA;

2002–2005
5506

(3205, 58.2%)
N/A 30–79 AUA-SI ≥ 8;

SF-12
N/A 18.6% N/A Blacks; Hispanics; Whites; (no differences) In-person and self-administered
Nørby et al 2005 [37] Denmark;

N/A
5379

(427, 7.9%)
47.7 d ≥50 I-PSS≥8 7 20% N/A N/A Mailed
Agarwal et al 2014 [29] Finland;

2003–2004
3727

(1888, 53.7%)
62.4 18–79 ICS;

DAN-PSS
12 N/A Population:

Urgency: 7.9%;

SUI: 6.5%;

Nocturia: 6.0%
N/A Mailed
Zumrutba et al 2014 [20] Turkey;

2012
1555

(919, 57.1%)
74 ≥18 2002 ICS;

Self-designed;

ICIQ-SF(UI)
18 Any:71.0% a ;

Storage: 64.1%; Voiding: 37.8%;

Urgency: 35.6%; Any UI:38.7%;

Nocturia: 31.0% a or 18.6% b ;

MUI: 9.0%; SUI: 21.2%; UUI: 3.3%;

SUI: 25.5%
N/A N/A Self-administered,

trained physicians and nurses helped
Herschorn et al 2008 [36] Canada;

2002
1,000

(518, 51.8%)
N/A ≥18 ICS;

Self designed
6 Any: 56.8% a or 40.9% b ;

Nocturia: 39.4% a or 10.2% b ;

UI: 28.8%; UUI:9.3%;

Frequency: 14.9%; Urgency: 14.1%
N/A N/A Telephone survey
Homma et al 2006 [8] Japan;

N/A
4570

(2380, 53.1%)
45 ≥40 Self-designed and validated 8 Frequency: 50.0%; Nocturia:69.0% a ;

Other LUTS: 2–27% (≥1 times/wk);

Other LUTS: 2–20% (≥1 times/d)
Nocturia;

SUI
N/A Self-administered
Lee et al 2011 [18] Korea;

2006
2000

(1112, 55.6%)
22.1 ≥18 ICS;

European EPIC questionnaire;

I-PSS
N/A Any: 68.9%;

Storage: 64.4% a and 47.4% b ;

Voiding:25.9%; Postmicturition 13.9%;

Nocturia:48.2% a and 14.0% b ;

UI: 28.4%; SUI:20.7%; MUI: 4.1%
(8 ≤ I-PSS ≤ 18)

5.8%;

(19 ≤ I-PSS ≤ 35)

0.8%
N/A Telephone survey
Zhang et al 2005 [14] China (Fuzhou);

2004
4684 women 77.2 ≥20 ICS;

BFLUTS
12 Any: 39.7% a

Storage: 37.3%; Voiding: 13.4%;

SUI: 16.6%;UUI: 10.0%; Urgency: 10.2%;

Frequency: 16.4%; Nocturia: 9.9%;

Hesitancy: 6.8%; Intermittence: 4.8%;

Straining: 4.5%
N/A Han Mailed
Our study China (nationwide)

2006
18 992 women 94.96 ≥20 ICS;

ICIQ-FLUTS
10 Any: 55.5% b

Storage: 53.9% b ; Voiding: 12.9%;

SUI: 18.9%;UUI: 2.6%; Urgency: 23.3%;

Frequency: 17.3%; Nocturia: 23.4% b ;

Hesitancy: 5.6%; Intermittence: 7.1%;

Straining: 3.3%; Pain/burning:4.5%
Urgency:29.93%;

UUI: 27.6%
Predominantly

Han
Interviewer-

administered

* This table does not include every published study; only the major or largest studies from each country from 2002 to November 2014 are presented here.

a Nocturia defined as ≥1 times/night.

b Nocturia defined as ≥2 times/night.

c This information was not reported in the paper but was deduced or calculated by us.

d The women's response rate, not the total response rate.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; SUI = stress urinary incontinence; UUI = urgency urinary incontinence; N/A = this information was not reported in the paper; BFLUTS = Bristol Female Lower Urinary Tract Symptoms; DAN-PSS = Danish Prostatic Symptom Score; ICS = International Continence Society; I-PSS = International Prostate Symptom Score; LUTS = lower urinary tract symptoms; AUA-SI = American Urological Association Symptom Index; SF-12 = Medical Outcomes Study 12-item Short Form Survey; ICIQ-FLUTS = International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms.

Individual prevalence comparisons may be more appropriate than overall prevalence comparisons among studies. LUTS in our study more commonly involved urinary storage problems rather than voiding difficulties, which were also reported for Western studies [6], [7], [14], [17], [18], and [20]. In the EPIC study, the ICS definition of nocturia (two or more voids per night) yielded similar prevalence (24.0%) to ours [7] . However, the prevalence rates for SUI, UUI, or UI reported by the participants in our study were much lower than those in the Western studies (4.5–44%) [5], [17], [18], [21], and [22]. There seem to be ethnic differences. Asian women were less prone to UI or LUTS, which is in line with a global prevalence analysis by Milsom et al [23] and an incidence study by Townsend et al [24] . Some of the differences observed can probably be attributed to methodological differences among studies. However, several racially and ethnically diverse studies also yielded ethnic differences in LUTS prevalence [5], [6], and [21]. These differences may result from many sociocultural and environmental factors, in addition to genetic factors that can affect bladder health, and require further study to distinguish.

4.1. Symptom-specific bother of individual LUTS

Assessment of the bother of symptoms is of key clinical relevance because it relates to both quality-of-life impairment and treatment-seeking [25] . Clinical practice guidelines suggest that only patients reporting bothersome symptoms should be targeted for intervention and that watchful waiting is appropriate for those with minimal symptoms [26] . There is a need to assess the frequency of individual LUTS and their respective bother ratings.

All of the individual LUTS caused bother, and storage symptoms were more likely to cause moderate or severe bother than voiding symptoms, especially urgency or UUI. We found that symptoms and bother did not correspond in a straightforward manner. Nocturia was most frequently rated as bothersome; however, it was primarily rated as no bother or as a minor bother. Urgency and UUI were less frequently rated as bothersome and usually ranked as severe or moderate. This information could assist in targeting patients who need intervention. Our study revealed similar findings to those of Moreira et al [6] , who also noted that urgency was usually associated with moderate or severe bother, whereas nocturia was usually associated with minor bother. Our study is partly in line with those of Coyne et al [27] and Møller et al [28] , who reported that the symptoms most frequently rated bothersome were nocturia, SUI, and urgency [27] and [28], and is similar to a national Finnish study that showed a high burden of urgency and UUI [29] . Because urgency seems to have a more negative impact on patient quality of life, it should be a leading consideration for medical intervention.

4.2. Potential risk factors for LUTS

The pathogenesis of LUTS is not completely understood, but it is considered a multifactorial process. A broader view of LUTS has shown that potential risk factors include age, race, micturition habits, lifestyle factors, and pathologic conditions [30] . We performed a detailed evaluation of potential risk factors for any, individual, and bothersome LUTS, and found that all were influenced by multiple factors. Older age and coexisting POP were both strong predictors for every type of LUTS. Regardless of the number of pregnancies, women who had only cesarean deliveries had no increase in odds for LUTS of any type. Women with multiple vaginal deliveries had increased odds for storage and bothersome LUTS compared with those who had spontaneous vaginal single births, in agreement with prospective studies focusing on reproductive history and progression of LUTS [31] and [32]. Prolonged labor may have a strong influence on any severely bothersome LUTS. Voiding symptoms were less likely to be associated with multiple vaginal deliveries or higher BMI. Multiple vaginal deliveries and prolonged labor may cause repeated injury to the muscles, nerves, and connective tissue of the pelvic floor, and have a negative impact on bladder control. The close relationship between LUTS and POP has rarely been explored. Having either incontinence or prolapse may be associated with an increased risk of developing the other condition [33] . It is possible that women with advanced POP experience more obstructive urinary symptoms, as reported by Rosenzweig et al [34] and Raz et al [35] . Family studies and twin studies have demonstrated that LUTS and POP are both heritable [33] . Our study, however, is cross-sectional, and the risk factors we identified cannot be considered established causes of LUTS. Some of the results should be interpreted with caution.

The strengths of our study are the large representative population-based sample of women and the high response rate. These enabled us to accurately determine the prevalence and bother associated with LUTS. The use of a professional questionnaire for urinary symptoms based strictly on criteria in the 2002 ICS guidelines also enabled us to compare our results with those for other studies.

Our study has some limitations. This analysis was the second of a study conducted 8 yr ago; the prevalence of LUTS may be higher today than at that time. Missing data were not handled well in our study. In addition, our questionnaire did not assess all LUTS, and the cross-sectional design is poor way to ascertain risk factors. Longitudinal studies are needed to better understand the temporal nature and associations with persistence of LUTS.

This was the largest population-based epidemiological study to date of LUTS in adult women. In the 55.5% of adult Chinese women who experienced LUTS, the most prevalent symptoms were nocturia, urgency, and SUI. Urgency and UUI were most frequently reported as moderately or severely bothersome. The likelihood of any, individual, and bothersome LUTS may involve multiple factors, with older age and coexisting POP as strong predictors.

Author contributions: Lan Zhu had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Zhu, Lang.

Acquisition of data: Zhu, Li, Gong, Q. Liu, X. Liu, Zhang.

Analysis and interpretation of data: Zhang, Xu, Zhu.

Drafting of the manuscript: Zhang.

Critical revision of the manuscript for important intellectual content: Zhu, Lang.

Statistical analysis: Zhang, Xu.

Obtaining funding: Zhu, Lang.

Administrative, technical, or material support: None.

Supervision: None.

Other (specify): None.

Financial disclosures: Lan Zhu certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: None.

Funding/Support and role of the sponsor: This study received financial support from the Chinese government under 5-year national project number 3053750. The only role of the sponsor was in approval of the manuscript.

Acknowledgments: We are grateful to the Bristol Urological Institute (Bristol, UK) for authorization of their Female Lower Urinary Tract Symptoms (BFLUTS) questionnaires. We would like to thank Shaomei Han for her professional guidance in data analysis.

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Lower urinary tract symptoms (LUTS) have attracted substantial attention in recent years partly because to their high prevalence but primarily because of heightened awareness of their detrimental impact on health-related quality of life [1] . Studies report that one in five adult women complain about moderate to severe LUTS, and one in ten adults have newly developed LUTS, often along with resulting substantial bother and interference with daily activities [2] and [3]. By 2018, an estimated 2.3 billion people will be affected by at least one LUTS. The prevalence of LUTS is likely to be greater in women than in men. The regional burden of these conditions is estimated to be greatest in Asia [1] . Many large-scale epidemiologic studies of LUTS have been conducted in Western countries, and prevalence estimates reported for LUTS subsets vary widely from 13% to 76% [4] and [5]. This variation could be due to differences in study populations, symptom assessment, data collection, or definitions used [3], [6], and [7]. In China, there have been relatively few epidemiologic studies of LUTS. Several studies have estimated the prevalence of LUTS in Asian countries such as Japan, Korea, and Taiwan [8], [9], and [10]; however, there are notable inconsistencies in the prevalence rates reported across studies, and few were conducted nationwide. In addition, many were limited by bias related to sex, specific LUTS, and age groups.

The aim of this study was to provide estimates of the prevalence and potential risk factors of LUTS and the bother they impose in a nationwide population-based sample of adult women in China.

2.1. Study design and participants

This analysis is the second of a previous study. The data were from a national cross-sectional survey on urinary incontinence (UI) in 20 000 adult women aged ≥20 yr in China. The previous survey included two phases: a pilot study conducted in Beijing, China [11] , and a subsequent nationwide study [12] and [13]. Detailed study procedures and results for stress urinary incontinence (SUI), urgency urinary incontinence (UUI), and mixed urinary incontinence (MUI) have been described in previous reports [11], [12], and [13].

Phase 1 (a pilot survey in Beijing) assessed a representative sample of approximately 5221 respondents (from one urban district and one rural district) who were interviewed face to face by trained interviewers using a standardized questionnaire. The eligibility criteria stipulated women aged ≥20 yr in the general population who had lived in the registered areas for at least 10 yr. We excluded women who were medically diagnosed with cognitive impairment and who could not understand the questions. Detailed study procedures and results were published [11] .

Phase 2 was a nationwide survey conducted between February and July 2006 in six regions of China. The sampling process was multistage and stratified according to geographic region (northwest, southwest, north, east, northeast, and central-south China) and degree of urbanization (large cities and undeveloped economic status were assessed on the basis of the gross domestic product for each province). Eligibility and exclusion criteria were in accord with the pilot survey (on the basis of Chinese population data from 2006). The rationale for the recruitment approach, the study design, and the interpretation of results has been described previously [12] and [13]. Ethics committee approval and written informed consent were obtained.

Our previous study focused on UI, so we recalculated the sample size for this reanalysis according to a previous study conducted in Fuzhou, China, which reported 39.7% prevalence of LUTS in female residents [14] . We aimed to survey at least six age deciles: 20–29, 30–39, 40–49, 50–59, 60–69, and ≥70 yr. A minimal sample size was calculated for detection of 39.7% prevalence of LUTS, with a 5% estimated error and a 95% confidence interval (CI). Considering a 20% refusal rate, a total of 16 805 participants would be required for the LUTS reanalysis according to the formula

FORMULA:

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The sample size was large enough for our reanalysis.

2.2. Diagnostic criteria

The definitions in this study are consistent with the standards recommended by the 2002 International Continence Society (ICS) guidelines [15] . Nocturia is a condition whereby a person awakens at night one or more times to void, and was defined as two or more micturitions per night in our study. Daytime frequency is a condition whereby a patient voids too often by day. In our study, frequency was defined as voiding eight times or more per day. Respondents who reported both UUI and SUI symptoms were classified as having MUI. Those who reported UI without symptoms of UUI or SUI were categorized as having other UI. Women who had given birth to multiple children were defined as having more than one delivery.

2.3. Measurements

We used a modified Bristol Female Lower Urinary Tract Symptoms questionnaire [16] that consisted of two parts. Part 1 included general information about age, marital status, occupation, menopausal status, medically diagnosed disease status, parity, mode of delivery for childbirth, and offspring birth weights. Part 2 was a Chinese version of the International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms (ICIQ-FLUTS). The Chinese version of the questionnaire was translated by survey research experts. To assess the accuracy of the translation, the Chinese version was translated back to English and compared by an independent agent. A pilot study of 40 women was performed before the survey took place to ensure the validity of the questionnaire. The readability of the Chinese version of the questionnaire was at the primary school level.

The questionnaire included an assessment of ten types of LUTS: nocturia, daytime frequency, urgency, UUI, SUI, other incontinence, pain or burning, hesitancy, straining, and intermittency. Participants were asked to rate how often individual LUTS were experienced during the previous 4 wk and, if LUTS were experienced, to what degree the symptoms were bothersome. All subjects reporting LUTS were asked to describe the frequency of the symptoms. Nocturia was measured as the number of micturitions per night, and frequency was defined as eight or more times per day. The other symptoms were measured according to how long participants had experienced them in the previous 4 wk, classified as: no (never); <10 d (occasionally); 10–20 d (sometimes); 20 d (most of the time); or every day (all of the time). The prevalence of other LUTS was defined as answers other than no. The bother associated with each symptom was evaluated using a scale ranging from 0 (not bothered at all) to 10 (greatly bothered). Bother was also defined by dividing the Likert responses into three groups: minor (rated 1–4), moderate (rated 5–7), and severe (rated 8–10). Detailed information on sociodemographic background, reproductive factors, defecation, and medical conditions was also collected. The interviewers underwent standardized training and regular quality control checks.

2.4. Statistical analysis

The data were finally stratified into eight age deciles. We performed χ2 tests to compare prevalence differences between groups. Receiver operating characteristic (ROC) curve distribution was used to assess the number of deliveries and their relationship to LUTS with moderate or severe bother. A multivariate model was set up to assess bother and individual LUTS-related potential risk factors and to estimate odds ratios and 95% CIs; this model was adapted for all factors in the final version. A two-sided p value ≤0.05 was considered for statistical significance. EpiData software ( http://www.epidata.dk/ ) was used for data entry and error detection. SPSS v.12.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis.

As shown in Figure 1 , 976 (4.88%) of the questionnaires could not be evaluated and were excluded in the previous UI study; 32 participants were further excluded because of missing information regarding reproductive factors or LUTS symptoms. A total of 18 992 participants (94.96%) were entered into our data analyses. The age distribution ranged from 20 to 99 yr, with a mean of 44.9 yr (±15.9 yr) (the age distribution in our study was similar to the total adult population in the 2006 National Census). Overall, 438 participants (2.3%) were from minority groups. The numbers of participants from urban and rural areas were equal (50% vs 50%). Table 1 lists the sociodemographic characteristics of the participants.

gr1

Fig. 1 Study flowchart. UI = urinary incontinence; LUTS = lower urinary tract symptoms.

Table 1 Characteristics of the 18 992 subjects interviewed

Characteristic Data
Mean age, yr (SD) 44.91 (15.9)
Age, n (%)
 20–29 yr 3381 (17.8)
 30–39 yr 4778 (25.2)
 40–49 yr 4199 (22.1)
 50–59 yr 2881 (15.2)
 60–69 yr 2029 (10.7)
 70–79 yr 1194 (6.3)
 80–89 yr 442 (2.3)
 ≥90 yr 88 (0.5)
Residence, n (%)
 Urban 9490 (50.0)
 Rural 9502 (50.0)
Current marital status, n (%)
 Single, never married 1392 (7.3)
 Married 15 976 (84.1)
 Remarried 178 (0.9)
 Divorced/separated 77 (0.4)
 Widowed 1369 (7.2)
Mean body mass index, kg/m2 (SD) 23.4 (3.8)
Body mass index, n (%)
 Underweight (<18.5 kg/m2) 1140 (6.0)
 Normal (18.5–23.9 kg/m2) 10 370 (54.6)
 Overweight (24–27.9 kg/m2) 5480 (28.9)
 Obese (≥28 kg/m2) 2002 (10.5)
Median parity, pregnancies (range) 1 (0–10)
Parity, n (%)
 Nulliparous 2251 (11.9)
 Primiparous (=1) 8980 (47.3)
 Multiparous (=2) 4286 (22.6)
 Multiparous (≥3) 3475 (18.3)
Job, n (%)
 Manual labor 4343 (22.9)
 Intellectual labor 14 649 (77.1)
Race, n (%)
 Han 18 554 (97.7)
 Minority 438 (2.3)

3.1. Prevalence of LUTS

The frequencies of individual LUTS are shown in Table 2 . The prevalence of any LUTS was 55.5% and increased with age. Storage symptoms were more common than voiding symptoms (53.9% vs 12.9%). Nocturia was the most common symptom (23.4%), followed by urgency (23.3%) and SUI (18.9%); incontinence was also highly prevalent (31.9%). Straining was the least common symptom (3.3%; Table 2 ).

Table 2 Prevalence of individual lower urinary tract symptoms by age and residence

  Symptoms, n (%)
  Total Age group Residence
  (n = 18 992) 20–29 yr 30–39 yr 40–49 yr 50–59 yr 60–69 yr 70–79 yr 80–90 yr ≥90 yr p value b Urban Rural p value b
    (n = 3381) (n = 4778) (n = 4199) (n = 2881) (n = 2029) (n = 1194) (n = 442) (n = 88)   (n = 9490) (n = 9502)  
Nocturia
 ≥2 times/night 4450 (23.4) 302 (8.9) 542 (11.3) 745 (17.7) 900 (31.2) 891 (43.9) 715 (59.9) 289 (65.4) 66 (75.0) <0.001 2161 (22.8) 2289 (24.1) 0.032
Frequency 3290 (17.3) 438 (13.0) 654 (13.7) 666 (15.9) 583 (20.2) 454 (22.4) 329 (27.6) 133 (30.1) 33 (37.5) <0.001 1934 (20.4) 1356 (14.3) <0.001
Urgency 4430 (23.3) 399 (11.8) 774 (16.2) 966 (23.0) 847 (29.4) 655 (32.3) 503 (42.1) 237 (53.6) 49 (55.7) <0.001 2361 (24.9) 2069 (21.8) <0.001
UI
 Any UI 6052 (31.9) 362 (10.7) 948 (19.8) 1488 (35.4) 1316 (45.7) 990 (48.8) 643 (53.9) 247 (55.9) 58 (65.9) <0.001 2733 (28.8) 3319 (34.9) <0.001
 UUI 488 (2.6) 35 (1.0) 73 (1.5) 84 (2.0) 81 (2.8) 94 (4.6) 97 (8.1) 23 (5.2) 1 (1.1) <0.001 272 (2.9) 216 (2.3) 0.01
 SUI 3,592 (18.9) 178 (5.3) 659 (13.8) 993 (23.6) 812 (28.2) 556 (27.4) 286 (24.0) 85 (19.2) 23 (26.1) <0.001 1555 (16.4) 2037 (21.4) <0.001
 MUI 1,788 (9.4) 43 (1.3) 206 (4.3) 398 (9.5) 405 (14.1) 320 (15.8) 247 (20.7) 136 (30.8) 33 (37.5) <0.001 752 (7.9) 1036 (10.9) <0.001
Other UI 858 (4.5) 123 (3.6) 71 (1.5) 138 (3.3) 174 (6.0) 145 (7.1) 134 (11.2) 52 (11.8) 21 (23.9) <0.001 468 (4.9) 390 (4.1) 0.006
 Any involuntary a 536 (2.8) 13 (0.4) 50 (1.0) 95 (2.3) 110 (3.8) 100 (4.9) 102 (8.5) 45 (10.2) 21 (23.9) <0.001 235 (2.5) 301 (3.2) 0.004
 Nocturnal enuresis 172 (0.9) 10 (0.3) 12 (0.3) 27 (0.6) 30 (1.0) 25 (1.2) 40 (3.4) 19 (4.3) 9 (10.2) <0.001 105 (1.1) 67 (0.7) 0.004
 During intercourse a 336 (2.0) 110 (3.7) 30 (0.6) 53 (1.3) 72 (2.8) 42 (3.0) 27 (4.2) 2 (1.1) 0 <0.001 227 (2.7) 109 (1.3) <0.001
Pain/burning 854 (4.5) 71 (2.1) 175 (3.7) 208 (5.0) 167 (5.8) 130 (6.4) 65 (5.4) 29 (6.6) 9 (10.2) <0.001 374 (3.9) 480 (5.1) <0.001
Hesitancy 1072 (5.6) 137 (4.1) 171 (3.6) 167 (4.0) 200 (6.9) 155 (7.6) 152 (12.7) 71 (16.1) 19 (21.6) <0.001 675 (7.1) 397 (4.2) <0.001
Straining 626 (3.3) 39 (1.2) 87 (1.8) 117 (2.8) 110 (3.8) 110 (5.4) 101 (8.5) 44 (10.0) 18 (20.5) <0.001 378 (4.0) 248 (2.6) <0.001
Intermittency 1346 (7.1) 110 (3.3) 211 (4.4) 231 (5.5) 259 (9.0) 233 (11.5) 197 (16.5) 83 (18.8) 22 (25.0) <0.001 801 (8.4) 545 (5.7) <0.001
Storage symptoms 10 245 (53.9) 1117 (33.0) 1930 (40.4) 2299 (54.8) 1956 (67.9) 1500 (73.9) 987 (82.7) 375 (84.8) 81 (92.0) <0.001 5249 (55.3) 4996 (52.6) <0.001
Voiding symptoms 2444 (12.9) 249 (7.4) 452 (9.5) 475 (11.3) 461 (16.0) 393 (19.4) 271 (22.7) 113 (25.6) 30 (34.1) <0.001 1353 (14.3) 1091 (11.5) <0.001
Any LUTS 10 540 (55.5) 1185 (35.0) 2034 (42.6) 2360 (56.2) 1988 (69.0) 1521 (75.0) 992 (83.1) 378 (85.5) 82 (93.2) <0.001 5420 (57.1) 5120 (53.9) <0.001

a 16 695 women were sexually active and included in the category UI during sexual intercourse. The category Any involuntary represents women who reported leaking for no reason or any involuntary loss of urine.

b The Pearson χ2 test was used to compare differences in the prevalence of individual LUTS by age and residence.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence.

A notable age-related trend was observed for the prevalence of any LUTS, storage, or voiding symptoms, with approximately 50% greater prevalence observed for the oldest compared to the youngest participants ( Table 2 ; Fig 2 and Fig 3). UI was frequent in women aged ≤70 yr, but nocturia was more prevalent in those aged ≥70 yr. Urgency was usually reported by women aged ≤50 yr. Frequency, urgency, hesitancy, straining, and intermittency were more common in urban women (p < 0.001). Rural women experienced more nocturia (22.8% vs 24.1%; p = 0.032). UI was the most common symptom (28.8% vs 34.9%; p < 0.001) in both areas, but particularly in rural areas ( Fig. 3 ).

gr2

Fig. 2 Age-specific prevalence of lower urinary tract symptom subtypes. UI = urinary incontinence.

gr3

Fig. 3 Urban and rural prevalence differences for individual lower urinary tract symptoms. UI = urinary incontinence.

3.2. Symptom-specific bother of LUTS

The extent to which study participants were bothered by each urinary symptom is summarized in Table 3 and Fig. 4 . We found that no bother or minor bother were the most common responses reported for every symptom. Only 14.6–29.9% of participants with bothersome LUTS reported a moderate to severe impact on their quality of life; 4.2–11.5% reported severe bother. Some of the most prevalent symptoms were among those least commonly reported as bothersome, such as SUI (67.4%). Some of the most likely to be rated as bothersome were not necessarily the most likely to cause moderate or severe bother, such as nocturia (19.5%). Urgency was among the least likely to cause bother but was the symptom most likely to cause severe (11.5%) or moderate to severe bother (29.9%), followed by UUI (10.8% and 27.6%, respectively). Frequency was the storage symptom that was least commonly reported as causing moderate or severe bother (14.6%).

Table 3 Self-reported bother related to individual lower urinary tract symptoms

Bother Symptoms, n (%)
  Nocturia Frequency Urgency UUI a SUI Pain/burning Hesitancy Straining Intermittency
Likert score
 0 14 854 (78.21) 17 090 (89.99) 16 242 (85.52) 17 245 (90.80) 15 366 (80.91) 18 270 (96.20) 18 333 (96.53) 18 527 (97.55) 18 136 (95.49)
 1 1505 (7.92) 818 (4.31) 771 (4.06) 534 (2.81) 1302 (6.86) 285 (1.50) 271 (1.43) 156 (0.82) 284 (1.50)
 2 879 (4.63) 426 (2.24) 553 (2.91) 329 (1.73) 868 (4.57) 173 (0.91) 140 (0.74) 114 (0.60) 200 (1.05)
 3 625 (3.29) 271 (1.43) 403 (2.12) 277 (1.46) 540 (2.84) 97 (0.51) 100 (0.53) 64 (0.34) 136 (0.72)
 4 322 (1.70) 110 (0.58) 200 (1.05) 126 (0.66) 269 (1.42) 56 (0.29) 46 (0.24) 32 (0.17) 75 (0.39)
 5 284 (1.50) 94 (0.49) 256 (1.35) 149 (0.78) 247 (1.30) 47 (0.25) 34 (0.18) 34 (0.18) 58 (0.31)
 6 141 (0.74) 67 (0.35) 149 (0.78) 97 (0.51) 108 (0.57) 16 (0.08) 24 (0.13) 24 (0.13) 35 (0.18)
 7 133 (0.70) 36 (0.19) 103 (0.54) 46 (0.24) 80 (0.42) 11 (0.06) 12 (0.06) 7 (0.04) 17 (0.09)
 8 137 (0.72) 41 (0.22) 147 (0.77) 86 (0.45) 85 (0.45) 20 (0.11) 12 (0.06) 16 (0.08) 25 (0.13)
 9 112 (0.59) 39 (0.21) 168 (0.88) 103 (0.54) 127 (0.67) 17 (0.09) 20 (0.11) 18 (0.09) 26 (0.14)
 10 0 0 0 0 0 0 0 0 0
Any bother b 4138 1902 2750 1747 3626 722 659 465 856
Moderate to severe bother 807 (19.50) 277 (14.56) 823 (29.93) 483 (27.60) 647 (17.84) 111 (15.37) 102 (15.48) 99 (21.29) 161 (18.81)
Any severe bother 249 (6.02) 80 (4.21) 315 (11.45) 189 (10.80) 212 (5.85) 37 (5.12) 32 (4.86) 34 (7.31) 51 (5.96)
Any LUTS 4450 3290 4430 2276 5380 854 1072 626 1346
Bother rate (%) 92.99 57.81 62.08 76.78 67.40 84.54 61.47 74.28 63.60

a SUI and UUI include participants with mixed urinary incontinence.

b Any bother: participants reported that they were bothered by at least one individual LUTS.

UUI = urgency urinary incontinence; SUI = stress urinary incontinence; LUTS = lower urinary tract symptoms.

gr4

Fig. 4 Symptom-specific bother and extent of individual lower urinary tract symptoms. Bother was also defined by dividing the Likert responses into three groups: (a) 1–4, minor; (b) 5–7, moderate; and (c) 8–10, severe. UUI = urgency urinary incontinence; SUI = stress urinary incontinence.

Voiding symptoms were less likely to cause moderate or severe bother than storage symptoms (p < 0.001). Pain or burning was the second most frequent bother (84.5%), but straining and intermittency were more likely to cause moderate or severe bother (21.3% and 18.8%, respectively; Table 3 ).

3.3. Potential risk factors for LUTS

Risk factors for LUTS according to logistic regression analysis are shown in Table 4, Table 5, and Table 6. We identified multiple risk factors for any, individual, and bothersome LUTS; older age, postmenopausal status, constipation, and coexisting pelvic organ prolapse (POP) increased the odds for every type of LUTS. Older age and coexisting POP were both strong predictors (p ≤ 0.05). In comparison with spontaneous vaginal single births, our study showed a higher risk of storage and moderate or severe bothersome LUTS in women with multiple vaginal deliveries (1.46-fold and 1.26-fold, respectively) and instrumental deliveries (1.25-fold and 1.22-fold, respectively). ROC distributions showed that multiple deliveries were more closely related to any severely bothersome LUTS ( Fig. 5 ). Women who had single or multiple deliveries via cesarean section had no increase in odds for every LUTS (p > 0.05), as did women who had spontaneous vaginal single births. Participants with histories of prolonged labor and perineal laceration had increased odds for moderate or severe bothersome LUTS; prolonged labor may have a stronger influence (1.99-fold, with adjustment for all other factors). Voiding symptoms were less influenced by delivery histories. Lifestyle factors and pathologic conditions such as higher body mass index (BMI), hypertension, diabetes, alcohol consumption, and smoking had various effects on any, individual, and bothersome LUTS (Table 4, Table 5, and Table 6).

Table 4 Multivariate analyses of associations between patient characteristics and bothersome lower urinary tract symptoms

  n (%) Any LUTS bother (n = 6950) Moderate to severe LUTS bother (n = 1695) Any severe LUTS bother (n = 652)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted OR a 95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) <0.001 1.43 1.26, 1.63 0.078 1.29 0.97, 1.71 0.072 1.63 0.96, 2.79
 40–49 yr 4199 (22.1) <0.001 1.85 1.62, 2.12 <0.001 2.04 1.54, 2.69 <0.001 2.91 1.73, 4.90
 50–59 yr 2881 (15.2) <0.001 2.08 1.75, 2.47 <0.001 2.71 1.96, 3.74 <0.001 4.99 2.83, 8.80
 60–69 yr 2029 (10.7) <0.001 2.12 1.73, 2.60 <0.001 2.29 1.60, 3.28 <0.001 4.45 2.41, 8.20
 70–79 yr 1194 (6.3) <0.001 2.75 2.21, 3.43 <0.001 2.70 1.86, 3.91 <0.001 5.16 2.77, 9.64
 80–89 442 (2.3) <0.001 3.59 2.74, 4.71 <0.001 3.58 2.39, 5.37 <0.001 6.59 3.40, 12.78
  ≥90 yr 88 (0.5) <0.001 9.24 5.19, 16.47 <0.001 7.30 4.18, 12.77 <0.001 16.56 7.59, 36.10
Residence   <0.001     0.109     0.846    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.16 1.08, 1.24   1.10 0.98, 1.23   1.02 0.86, 1.21
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.66 1.49, 1.86 <0.001 1.79 1.48, 2.15 <0.001 2.26 1.68, 3.02
 Postmenopausal status 6178 (32.5) <0.001 1.55 1.35, 1.77 <0.001 1.55 1.25, 1.92 0.016 1.51 1.08, 2.12
Body mass index   <0.001     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.425 1.06 0.91, 1.24 0.008 1.41 1.09, 1.81 0.844 0.96 0.60, 1.51
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.16 1.08, 1.25 <0.001 1.29 1.15, 1.46 0.001 1.38 1.14, 1.66
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.47 1.27, 1.71 <0.001 1.70 1.37, 2.10 <0.001 1.81 1.33, 2.48
Mode of delivery   <0.001     0.001     0.006    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.25 1.14, 1.36 0.002 1.26 1.09, 1.46 0.001 1.51 1.20, 1.92
 Forceps or vacuum delivery 746 (3.9) 0.026 1.20 1.02, 1.42 0.134 1.22 0.94, 1.58 0.240 1.29 0.85, 1.96
 Cesarean section                    
  1 2,399 (12.6) 0.001 0.83 0.75, 0.93 0.095 0.83 0.67, 1.03 0.502 0.87 0.59, 1.30
  ≥2 55 (3.0) 0.965 1.01 0.58, 1.77 0.401 1.42 0.63, 3.23 0.356 1.76 0.53, 5.83
 Nulliparity 2251 (11.9) <0.001 0.64 0.55, 0.74 0.050 0.74 0.54, 1.00 0.090 1.50 0.94, 2.41
Prolonged labor b   <0.001     <0.001     <0.001    
 No (ref.) 13 444 (95.7)   1.00     1.00     1.00  
 Yes 599 (4.3)   1.62 1.35, 1.94   1.99 1.58, 2.50   2.19 1.58, 3.02
Perineal laceration b   <0.001     0.018     0.700    
 No (ref.) 10 312 (77.0)   1.00 -   1.00     1.00  
 Yes 3088 (23.0)   1.22 1.12, 1.33   1.17 1.03, 1.34   1.04 0.85, 1.04
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.97 1.79, 2.16   2.22 1.95, 2.52   2.28 1.89, 2.76
Hormone replacement therapy   0.009     0.510     0.879    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.69 0.52, 0.91   1.17 0.74, 1.84   0.95 0.50, 1.82
Pelvic organ prolapse   <0.001     <0.001     0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.08 1.55, 2.77   2.29 1.65, 3.18   2.12 1.35, 3.35
Hypertension   <0.001     <0.001     0.017    
 Nonexistent (ref.) 17 093 (90.0)   1.00 -   1.00     1.00  
 Present 1899 (10.0)   1.48 1.33, 1.65   1.49 1.29, 1.72   1.29 1.05, 1.60
Diabetes   0.001     0.001     0.011    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.38 1.14, 1.67   1.48 1.18, 1.86   1.52 1.10, 2.10
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.25 1.11, 1.39   1.54 1.28, 1.85   2.10 1.56, 2.78
Alcohol consumption   <0.001     0.466     0.168    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.37 1.23, 1.52   1.07 0.90, 1.27   1.20 0.93, 1.56

a The adjusted odds ratios with 95% confidence intervals are presented. All of the factors, except for prolonged labor and perineal laceration, were adjusted in the multivariate model. For prolonged labor and perineal laceration, the other factors were adjusted. Pelvic organ prolapse, hypertension, and diabetes were defined according to hospital diagnosis.

b There were some missing data for prolonged labor (244) and perineal laceration (887) because the participants could not accurately recall these histories.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 5 Multivariate analyses of associations between patient characteristics and the presence of storage, voiding, and incontinence lower urinary tract symptoms

  n (%) Storage symptoms (n = 10 245) Voiding symptoms (n = 2444) Any urinary incontinence (n = 6052)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.001 1.21 1.09, 1.36 0.001 1.38 1.14, 1.67 <0.001 1.55 1.34, 1.80
 40–49 yr 4199 (22.1) <0.001 1.75 1.56, 1.98 0.001 1.42 1.16, 1.74 <0.001 2.66 2.29, 3.10
 50–59 yr 2881 (15.2) <0.001 2.00 1.70, 2.36 <0.001 1.57 1.22, 2.01 <0.001 2.80 2.32, 3.38
 60–69 yr 2029 (10.7) <0.001 2.01 1.64, 2.47 0.001 1.63 1.22, 2.18 <0.001 2.46 1.98, 3.06
 70–79 yr 1194 (6.3) <0.001 3.30 2.61, 4.17 <0.001 1.84 1.36, 2.48 <0.001 3.02 2.39, 3.81
 80–89 442 (2.3) <0.001 3.93 2.86, 5.39 <0.001 2.03 1.44, 2.86 <0.001 3.32 2.52, 4.37
 ≥90 yr 88 (0.5) <0.001 9.14 4.11, 20.29 <0.001 2.98 1.75, 5.05 <0.001 5.87 3.58, 9.65
Residence   <0.001     <0.001     0.006    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.35 1.26, 1.45   1.32 1.19, 1.45   0.90 0.84, 0.97
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.55 1.39, 1.73 <0.001 1.75 1.50, 2.05 <0.001 1.61 1.43, 1.81
 Postmenopausal status 6178 (32.5) <0.001 1.63 1.42, 1.87 <0.001 1.50 1.24, 1.82 <0.001 1.44 1.26, 1.65
Body mass index   <0.001     0.204     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.445 1.05 0.92, 1.21 0.138 0.85 0.68, 1.06 0.137 0.88 0.74, 1.04
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.31 1.23, 1.41 0.839 0.99 0.90, 1.09 <0.001 1.34 1.25, 1.45
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.87 1.59, 2.21 0.180 1.14 0.94, 1.39 <0.001 1.77 1.52, 2.06
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.46 1.34, 1.60 <0.001 1.31 1.15, 1.49 <0.001 1.63 1.49, 1.79
 Forceps or vacuum delivery 746 (3.9) 0.007 1.25 1.06, 1.48 0.002 1.41 1.14, 1.75 <0.001 1.35 1.14, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.044 0.90 0.82, 1.00 0.590 0.96 0.81, 1.12 <0.001 0.72 0.63, 0.81
  ≥2 55 (3.0) 0.234 0.71 0.41, 1.25 0.513 1.30 0.60, 2.83 0.247 0.69 0.37, 1.29
 Nulliparity 2251 (11.9) 0.042 0.88 0.77, 1.00 0.293 1.12 0.91, 1.37 <0.001 0.71 0.59, 0.84
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.77 1.60, 1.95   2.18 1.95, 2.43   1.87 1.70, 2.06
Hormone replacement therapy   0.050     0.001     0.211    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.75 0.56, 1.00   0.58 0.41, 0.81   0.83 0.63, 1.11
Pelvic organ prolapse   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.38 1.68, 3.36   2.35 1.72, 3.21   1.96 1.47, 2.60
Hypertension   <0.001     0.202     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.41 1.24, 1.61   1.09 0.95, 1.25   1.29 1.16, 1.44
Diabetes   0.001     <0.001     0.114    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.49 1.17, 1.89   1.61 1.31, 1.99   1.17 0.96, 1.41
Smoking   <0.001     <0.001     0.306    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.31 1.17, 1.46   1.70 1.46, 1.98   1.06 0.95, 1.20
Alcohol consumption   <0.001     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.22 1.10, 1.35   1.37 1.18, 1.59   1.51 1.35, 1.68

a All of the factors were adjusted.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 6 Multivariate analyses of the association between patient characteristics and individual LUTS and any LUTS with adjustment for all factors

  n (%) Nocturia (n = 4450) Frequency (n = 3290) Urgency (n = 4430)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.598 0.96 0.81, 1.13 0.013 1.22 1.04, 1.42 <0.001 1.56 1.33, 1.82
 40–49 yr 4199 (22.1) 0.002 1.30 1.10, 1.54 <0.001 1.44 1.22, 1.70 <0.001 2.07 1.76, 2.43
 50–59 yr 2881 (15.2) <0.001 1.84 1.50, 2.26 <0.001 1.58 1.27, 1.95 <0.001 2.20 1.80, 2.69
 60–69 yr 2029 (10.7) <0.001 2.63 2.08, 3.32 <0.001 1.72 1.34, 2.21 <0.001 2.05 1.62, 2.60
 70–79 yr 1194 (6.3) <0.001 5.13 4.00, 6.57 <0.001 2.26 1.74, 2.94 <0.001 3.03 2.37, 3.88
 80–89 442 (2.3) <0.001 7.08 5.29, 9.48 <0.001 2.59 1.91, 3.52 <0.001 4.66 3.49, 6.21
 ≥90 yr 88 (0.5) <0.001 12.95 7.60, 22.06 <0.001 3.47 2.13, 5.67 <0.001 5.19 3.19, 8.45
Residence   0.692     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   0.98 0.91, 1.07   1.45 1.33, 1.58   1.29 1.19, 1.39
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.43 1.25, 1.64 <0.001 1.42 1.24, 1.63 <0.001 1.41 1.24, 1.61
 Postmenopausal status 6178 (32.5) <0.001 1.57 1.35, 1.83 <0.001 1.52 1.28, 1.81 <0.001 1.35 1.16, 1.57
Body mass index   <0.001     0.055     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.133 1.15 0.96, 1.39 0.611 1.05 0.88, 1.24 0.844 1.02 0.85, 1.12
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.46 1.35, 1.59 0.392 1.04 0.95, 1.13 <0.001 1.24 1.14, 1.34
 Obese (≥28 g/m2) 2002 (10.5) <0.001 2.16 1.84, 2.54 0.006 1.28 1.07, 1.53 <0.001 1.56 1.33, 1.83
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.037 1.12 1.01, 1.24 0.002 0.83 0.74, 0.93 0.000 1.41 1.27, 1.57
 Forceps or vacuum delivery 746 (3.9) 0.685 1.04 0.86, 1.26 0.372 1.09 0.90, 1.33 0.002 1.34 1.11, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.707 0.97 0.85, 1.12 0.212 1.09 0.95, 1.24 0.132 1.10 0.97, 1.25
  ≥2 55 (3.0) 0.600 1.18 0.63, 2.20 0.247 0.62 0.28, 1.39 0.567 0.81 0.40, 1.66
 Nulliparity 2251 (11.9) <0.001 0.59 0.49, 0.72 0.004 1.28 1.08, 1.51 0.020 1.22 1.03, 1.44
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.52 1.37, 1.69   1.26 1.13, 1.40   1.84 1.66, 2.02
Hormone replacement therapy   0.039     0.388     0.009    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.73 0.54, 0.98   1.17 0.82, 1.66   0.67 0.50, 0.91
Pelvic organ prolapse   0.002     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   1.62 1.20, 2.17   1.78 1.32, 2.41   2.00 1.51, 2.67
Hypertension   <0.001     0.075     0.112    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.48 1.32, 1.65   1.12 0.99, 1.27   1.10 0.98, 1.23
Diabetes   <0.001     0.084     0.049    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.73 1.42, 2.10   1.20 0.98, 1.48   1.21 1.00, 1.47
Smoking   0.047     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.15 1.00, 1.33   0.59 0.52, 0.68   2.20 1.94, 2.49
Alcohol consumption   0.004     0.133     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   0.82 0.72, 0.94   1.10 0.97, 1.24   1.29 1.14, 1.45
  n (%) UUI (n = 488) SUI (n = 3592) MUI (n = 1788)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.017 1.77 1.11, 2.83 <0.001 1.78 1.47, 2.15 <0.001 2.28 1.59, 3.26
 40–49 yr 4199 (22.1) 0.003 2.08 1.28, 3.38 <0.001 2.74 2.26, 3.31 <0.001 4.09 2.88, 5.82
 50–59 yr 2881 (15.2) 0.022 1.99 1.10, 3.58 <0.001 2.62 2.09, 3.29 <0.001 4.94 3.36, 7.26
 60–69 yr 2029 (10.7) 0.001 2.83 1.49, 5.38 <0.001 2.21 1.71, 2.86 <0.001 4.57 3.01, 6.93
 70–79 yr 1194 (6.3) 0.000 5.03 2.64, 9.57 <0.001 1.87 1.42, 2.46 <0.001 6.40 4.18, 9.79
 80–89 442 (2.3) 0.003 3.00 1.45, 6.24 0.040 1.43 1.02, 2.00 <0.001 11.15 7.13, 17.44
 ≥90 yr 88 (0.5) 0.624 0.60 0.08 4.68 0.001 2.41 1.41, 4.14 <0.001 17.01 9.34, 30.95
Residence   0.022     0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.26 1.03, 1.53   0.87 0.80, 0.95   0.81 0.72, 0.90
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.89 1.34, 2.67 <0.001 1.37 1.20, 1.57 <0.001 1.69 1.40, 2.03
 Postmenopausal status 6178 (32.5) 0.004 1.86 1.22, 2.84 <0.001 1.33 1.15, 1.55 0.077 1.21 0.98, 1.49
Body mass index   0.454     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.706 1.09 0.70, 1.69 0.39 0.91 0.73, 1.13 0.001 0.56 0.40, 0.79
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.214 1.14 0.93, 1.40 <0.001 1.35 1.24, 1.47 0.058 1.12 1.00, 1.26
 Obese (≥28 g/m2) 2002 (10.5) 0.157 1.31 0.90, 1.91 <0.001 1.42 1.20, 1.68 <0.001 1.60 1.31, 1.96
Mode of delivery   0.182     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.176 1.21 0.92, 1.60 <0.001 1.25 1.12, 1.38 <0.001 1.85 1.60, 2.15
 Forceps or vacuum delivery 746 (3.9) 0.801 0.94 0.56, 1.57 0.007 1.28 1.07, 1.54 0.014 1.39 1.07, 1.81
 Cesarean section                    
  1 2,399 (12.6) 0.045 1.42 1.01, 2.01 <0.001 0.66 0.57, 0.77 0.257 0.88 0.70, 1.10
  ≥2 55 (3.0) 0.997 * * 0.544 0.81 0.40, 1.62 0.843 0.90 0.32, 2.55
 Nulliparity 2251 (11.9) 0.040 1.61 1.02, 2.54 <0.001 0.34 0.26, 0.44 0.004 0.56 0.38, 0.83
Constipation   0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.49 1.18, 1.88   1.28 1.15, 1.42   2.15 1.89, 2.45
Hormone replacement therapy   0.075     0.883     0.143    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.57 0.30, 1.06   1.03 0.74, 1.42   0.74 0.50, 1.11
Pelvic organ prolapse   0.001     0.050     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.40 1.41, 4.06   1.36 1.01, 1.86   2.31 1.66, 3.21
Hypertension   0.390     0.004     0.067    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.12 0.87, 1.44   1.19 1.06, 1.34   1.14 0.99, 1.32
Diabetes   0.564     0.030     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.12 0.76, 1.67   0.79 0.64, 0.98   1.54 1.23, 1.93
Smoking   0.755     0.084     0.927    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.05 0.76, 1.47   1.13 0.98, 1.29   1.01 0.84, 1.21
Alcohol consumption   0.906     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.02 0.75, 1.02   1.34 1.18, 1.52   1.54 1.30, 1.83
  n (%) Other UI (n = 858) Pain/burning (n = 854) Hesitancy (n = 1072)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     0.016     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.007 0.63 0.45, 0.88 0.010 1.52 1.11, 2.09 0.912 1.02 0.78, 1.33
 40–49 yr 4199 (22.1) 0.108 1.31 0.94, 1.81 0.001 1.75 1.26, 2.43 0.898 0.98 0.74, 1.31
 50–59 yr 2881 (15.2) 0.003 1.82 1.22, 2.72 0.015 1.65 1.10, 2.45 0.136 1.31 0.92, 1.87
 60–69 yr 2029 (10.7) 0.008 1.84 1.17, 2.89 0.062 1.55 0.98, 2.45 0.334 1.23 0.81, 1.86
 70–79 yr 1194 (6.3) <0.001 2.85 1.81, 4.51 0.503 1.19 0.72, 1.95 0.002 1.95 1.28, 2.98
 80–89 442 (2.3) <0.001 2.88 1.74, 4.76 0.317 1.34 0.76, 2.37 <0.001 2.43 1.53, 3.85
 ≥90 yr 88 (0.5) <0.001 6.18 3.26, 11.72 0.089 2.04 0.90, 4.64 <0.001 3.25 1.70, 6.21
Residence   0.143     0.021     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.12 0.96, 1.30   0.83 0.71, 0.97   1.64 1.42, 1.89
Menstrual condition   0.007     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) 0.010 1.43 1.09, 1.89 <0.001 1.90 1.51, 2.39 <0.001 1.72 1.36, 2.18
 Postmenopausal status 6178 (32.5) 0.010 1.51 1.11, 2.06 0.042 1.35 1.01, 1.81 0.002 1.57 1.18, 2.08
Body mass index   0.298     0.643     0.537    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.300 1.18 0.87, 1.60 0.555 0.89 0.62, 1.30 0.187 0.81 0.59, 1.11
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.079 1.16 0.98, 1.36 0.218 0.91 0.78, 1.06 0.701 0.97 0.84, 1.12
 Obese (≥28 g/m2) 2002 (10.5) 0.312 1.17 0.86, 1.59 0.796 0.96 0.70, 1.31 0.669 1.06 0.81, 1.40
Mode of delivery   <0.001     <0.001     0.086    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.213 1.15 0.93, 1.42 <0.001 1.59 1.30, 1.94 0.785 1.03 0.85, 1.25
 Forceps or vacuum delivery 746 (3.9) 0.657 1.09 0.75, 1.60 0.030 1.47 1.04, 2.07 0.024 1.40 1.05, 1.88
 Cesarean section                    
  1 2399 (12.6) 0.654 0.93 0.68, 1.27 0.104 1.23 0.96, 1.57 0.373 0.90 0.71, 1.14
  ≥2 55 (3.0) 0.681 1.28 0.39, 4.20 0.230 1.90 0.67, 5.40 0.555 0.65 0.15, 2.75
 Nulliparity 2251 (11.9) <0.001 2.40 1.77, 3.26 0.184 0.77 0.53, 1.13 0.170 1.21 0.92, 1.60
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.87 1.57, 2.22   2.18 1.84, 2.57   2.11 1.82, 2.45
Hormone replacement therapy   0.859     0.497     0.071    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   1.06 0.57, 1.97   1.27 0.64, 2.50   0.65 0.40, 1.04
Pelvic organ prolapse   <0.001     0.026     0.012    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.65 1.76, 4.00   1.74 1.07, 2.84   1.81 1.14, 2.88
Hypertension   0.206     0.284     0.022    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.14 0.93, 1.39   0.89 0.71, 1.11   1.24 1.03, 1.48
Diabetes   0.017     0.041     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.44 1.07, 1.93   1.41 1.01, 1.95   1.61 1.24, 2.10
Smoking   0.267     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.16 0.90, 1.50   2.16 1.68, 2.78   1.70 1.70, 2.65
Alcohol consumption   0.846     0.119     0.013    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.03 0.80, 1.31   1.22 0.95, 1.56   1.33 1.06, 1.66
  n (%) Straining (n = 626) Intermittency (n = 1346) Any LUTS (n = 10 540)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.006 1.84 1.19, 2.84 0.003 1.51 1.15, 1.99 <0.001 1.22 1.09, 1.36
 40–49 yr 4199 (22.1) <0.001 2.45 1.57, 3.81 0.001 1.65 1.24, 2.20 <0.001 1.71 1.51, 1.92
 50–59 yr 2881 (15.2) <0.001 2.64 1.57, 4.43 <0.001 2.08 1.48, 2.92 <0.001 1.91 1.62, 2.25
 60–69 yr 2029 (10.7) <0.001 3.29 1.85, 5.85 <0.001 2.27 1.54, 3.34 <0.001 1.92 1.56, 2.35
 70–79 yr 1194 (6.3) <0.001 4.72 2.63, 8.47 <0.001 3.22 2.17, 4.78 <0.001 3.05 2.41, 3.86
 80–89 442 (2.3) <0.001 5.31 2.84, 9.93 <0.001 3.66 2.37, 5.63 <0.001 3.71 2.69, 5.12
 ≥90 yr 88 (0.5) <0.001 11.61 5.45, 24.73 <0.001 5.05 2.75, 9.28 <0.001 9.63 4.10, 22.61
Residence   <0.001     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.44 1.20, 1.73   1.49 1.31, 1.69   1.37 1.28, 1.47
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.92 1.42, 2.60 <0.001 1.64 1.33, 2.04 <0.001 1.62 1.45, 1.81
 Postmenopausal status 6178 (32.5) 0.062 1.41 0.98, 2.03 0.002 1.49 1.16, 1.92 <0.001 1.68 1.46, 1.93
Body mass index   0.778     0.378     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.350 0.81 0.52, 1.26 0.147 0.80 0.59, 1.08 0.461 1.05 0.92, 1.20
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.860 0.98 0.82, 1.18 0.492 1.05 0.92, 1.19 <0.001 1.29 1.21, 1.38
 Obese (≥28 g/m2) 2002 (10.5) 0.731 1.10 0.75, 1.50 0.747 1.04 0.81, 1.34 <0.001 1.80 1.52, 2.13
Mode of delivery   0.391     0.196     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.340 1.13 0.88, 1.44 0.097 1.16 0.97, 1.37 <0.001 1.45 1.32, 1.58
 Forceps or vacuum delivery 746 (3.9) 0.136 1.34 0.91, 1.96 0.058 1.31 0.99, 1.72 0.002 1.29 1.10, 1.53
 Cesarean section                    
  1 2399 (12.6) 0.522 0.90 0.65, 1.24 0.824 0.98 0.79, 1.21 0.047 0.90 0.82, 1.00
  ≥2 55 (3.0) 0.575 0.56 0.08, 4.19 0.847 1.11 0.39, 3.16 0.387 0.78 0.45, 1.37
 Nulliparity 2251 (11.9) 0.241 1.27 0.85, 1.91 0.118 1.25 0.95, 1.64 0.031 0.87 0.77, 0.99
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   2.60 2.16, 3.11   2.00 1.74, 2.30   1.87 1.69, 2.06
Hormone replacement therapy   0.021     0.008     0.040    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.53 0.30, 0.91   0.58 0.38, 0.87   0.73 0.55, 0.99
Pelvic organ prolapse   0.004     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.17 1.29, 3.65   2.65 1.85, 3.80   2.37 1.67, 3.37
Hypertension   0.278     0.004     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.13 0.91, 1.42   1.27 1.08, 1.49   1.41 1.24, 1.61
Diabetes   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.81 1.33, 2.45   1.63 1.29, 2.08   1.60 1.25, 2.06
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.97 1.47, 2.63   1.46 1.20, 1.78   1.32 1.18, 1.48
Alcohol consumption   0.036     0.006     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.36 1.02, 1.82   1.31 1.08, 1.59   1.24 1.12, 1.38

* The sample was small, so the 95% CI could not be calculated.

OR c = odds ratio; CI = confidence interval; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence; LUTS = lower urinary tract symptoms.

gr5

Fig. 5 Receiver operating characteristic curve analysis for the relationship between number of deliveries and moderately or severely bothersome lower urinary tract symptoms (LUTS). (A) Moderately to severely bothersome LUTS in relation to number of deliveries. Area = 0.653; 95% confidence interval 0.639–0.667. When n = 2(1.5), the sensitivity is 63.1% and the specificity is 61.3%. (B) Any severely bothersome LUTS in relation to the number of deliveries. Area = 0.689; 95% confidence interval 0.666–0.711. When n = 2(1.5), the sensitivity is 70.0% and the specificity is 60.1%.

We conducted a PubMed search for English-language articles focused on epidemiology and bother of LUTS ( Table 7 ). The prevalence of any LUTS in our study was higher (55.5%) than in the large population-based EPIC study with an original five-nation European and North American survey (48.1%) [7] but lower than in an Internet-based study in the USA, the UK, and Sweden (76.3%) [5] and population-based studies in Brazil (84.1%) [6] , Russia, the Czech Republic, and Turkey (81–87%) [17] . The prevalence of any LUTS was lower than that in Korea (68.9%) [18] . In China, prevalence varies between studies. Hong Kong and Taiwan showed higher prevalence (74%) [19] , but a previous study in Fuzhou, China, identified an even lower rate (39.7%) [14] .

Table 7 Overview of published English-language population-based studies on the epidemiology and bother of lower urinary tract symptoms *

Study Countries/

Year conducted
Total no.

(women, n, %)
Response rate (%) Age (yr) Definition;

questionnaire
Numbers of LUTS

evaluated
Prevalence of any or individual LUTS in women (%) Moderate to severe bother (women %) Race Methods
Irwin et al 2006 [7] Canada; Germany;

Italy; Sweden; UK

2005
19 165

(N/A)
33 ≥18 2002 ICS;

Self-designed
18 Any: 66.6% a or 48.1% b ;

Nocturia: 54.5% a or 24.0% b ;

Storage: 59.2% a ; Voiding: 19.5%;

Urgency:12.8%; UI: 13.1%; SUI:6.4%;

Terminal dribble: 9.9%
N/A Predominantly white Computer-assisted telephone
Coyne et al 2009 [5] USA;

UK;

Sweden;

2007–2008
30 000

(15 861, 52.9%)

USA 20 000;

UK 7500;

Sweden 2500
59.6;

60.6;

52.3
40–99 2002 ICS;

self-designed;

questions according to ICS

definition
20 c Any: 76.3% (sometimes) or 52.5% (often);

Nocturia: 75.8% a or 33.7% b ;

Terminal dribble: 38.3%; Urgency: 35.7%;

Frequency: 24.6%;

SUI: 31.8%; UUI: 24.4%
Somewhat bothered:

Urgency: 74.7%;

SUI: 74%;

Dysuria: 73.5%

UUI: 71.3%
White; Black; Hispanic; Asian/other Internet-based
Koga et al 2014 [17] Russia;

Czech Republic;

Turkey;

2010
3130

(1614, 51.6%)
N/A ≥18 ICS;

European EPIC questionnaire
18 Any: 81%; 83%; 87% a ;

Storage: 74%, 73%, 81%;

Voiding: 41%, 32, 38%;

Postmicturition: 20%, 26%, 21%;

UI: 20%
Frequency: 58%;

Nocturia: 54%
N/A Computer-assisted telephone and face-to-face
Moreira et al 2013 [6] Brazil;

2006–2007
3000

(1500, 50.0%)
83 ≥30 2002 ICS;

Self-designed
18 c Any: 84.1% a

Storage: 76.4%; Voiding: 33.7%;

Postmicturition: 12.8%;

Nocturia: 71.2% a and 36.5% b ;

Frequency: 23.7%; Urgency: 10.0%;

UI: 5.8%; Terminal dribble: 13.0%
Any bother:

Urgency: 75%,

Nocturia: ≤50%
White; Black;

Mixed; Other
Interviewer-

administered
Coyne et al 2013 [21] USA;

2010
10 000

(5023, 50.2%)
56.7 18–70 ICS;

self-designed;

questions according to ICS

definition
11 c Any: N/A

Terminal dribble: 33.4%;

Nocturia: 27.8% b , c

Urgency: 24.4% c ; UUI: 18.5% c ;

Incomplete emptying: 20.9%**
N/A African-Americans; Hispanics; Whites Internet-based
Boyle et al 2003 [4] Netherlands;

France; UK; Korea;

N/A
8769

(3790, 43.2%)
N/A 40–79 I-PSS ≥ 8 7 c 18.0%; 12.6%; 23.7%; 19.9% 8 ≤ I-PSS ≤ 20: 11.0–19.5%;

20 ≤ I-PSS ≤ 35: 1.6–4.2%
N/A Self-completed

postal and direct
Kupelian et al 2006 [2] USA;

2002–2005
5506

(3205, 58.2%)
N/A 30–79 AUA-SI ≥ 8;

SF-12
N/A 18.6% N/A Blacks; Hispanics; Whites; (no differences) In-person and self-administered
Nørby et al 2005 [37] Denmark;

N/A
5379

(427, 7.9%)
47.7 d ≥50 I-PSS≥8 7 20% N/A N/A Mailed
Agarwal et al 2014 [29] Finland;

2003–2004
3727

(1888, 53.7%)
62.4 18–79 ICS;

DAN-PSS
12 N/A Population:

Urgency: 7.9%;

SUI: 6.5%;

Nocturia: 6.0%
N/A Mailed
Zumrutba et al 2014 [20] Turkey;

2012
1555

(919, 57.1%)
74 ≥18 2002 ICS;

Self-designed;

ICIQ-SF(UI)
18 Any:71.0% a ;

Storage: 64.1%; Voiding: 37.8%;

Urgency: 35.6%; Any UI:38.7%;

Nocturia: 31.0% a or 18.6% b ;

MUI: 9.0%; SUI: 21.2%; UUI: 3.3%;

SUI: 25.5%
N/A N/A Self-administered,

trained physicians and nurses helped
Herschorn et al 2008 [36] Canada;

2002
1,000

(518, 51.8%)
N/A ≥18 ICS;

Self designed
6 Any: 56.8% a or 40.9% b ;

Nocturia: 39.4% a or 10.2% b ;

UI: 28.8%; UUI:9.3%;

Frequency: 14.9%; Urgency: 14.1%
N/A N/A Telephone survey
Homma et al 2006 [8] Japan;

N/A
4570

(2380, 53.1%)
45 ≥40 Self-designed and validated 8 Frequency: 50.0%; Nocturia:69.0% a ;

Other LUTS: 2–27% (≥1 times/wk);

Other LUTS: 2–20% (≥1 times/d)
Nocturia;

SUI
N/A Self-administered
Lee et al 2011 [18] Korea;

2006
2000

(1112, 55.6%)
22.1 ≥18 ICS;

European EPIC questionnaire;

I-PSS
N/A Any: 68.9%;

Storage: 64.4% a and 47.4% b ;

Voiding:25.9%; Postmicturition 13.9%;

Nocturia:48.2% a and 14.0% b ;

UI: 28.4%; SUI:20.7%; MUI: 4.1%
(8 ≤ I-PSS ≤ 18)

5.8%;

(19 ≤ I-PSS ≤ 35)

0.8%
N/A Telephone survey
Zhang et al 2005 [14] China (Fuzhou);

2004
4684 women 77.2 ≥20 ICS;

BFLUTS
12 Any: 39.7% a

Storage: 37.3%; Voiding: 13.4%;

SUI: 16.6%;UUI: 10.0%; Urgency: 10.2%;

Frequency: 16.4%; Nocturia: 9.9%;

Hesitancy: 6.8%; Intermittence: 4.8%;

Straining: 4.5%
N/A Han Mailed
Our study China (nationwide)

2006
18 992 women 94.96 ≥20 ICS;

ICIQ-FLUTS
10 Any: 55.5% b

Storage: 53.9% b ; Voiding: 12.9%;

SUI: 18.9%;UUI: 2.6%; Urgency: 23.3%;

Frequency: 17.3%; Nocturia: 23.4% b ;

Hesitancy: 5.6%; Intermittence: 7.1%;

Straining: 3.3%; Pain/burning:4.5%
Urgency:29.93%;

UUI: 27.6%
Predominantly

Han
Interviewer-

administered

* This table does not include every published study; only the major or largest studies from each country from 2002 to November 2014 are presented here.

a Nocturia defined as ≥1 times/night.

b Nocturia defined as ≥2 times/night.

c This information was not reported in the paper but was deduced or calculated by us.

d The women's response rate, not the total response rate.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; SUI = stress urinary incontinence; UUI = urgency urinary incontinence; N/A = this information was not reported in the paper; BFLUTS = Bristol Female Lower Urinary Tract Symptoms; DAN-PSS = Danish Prostatic Symptom Score; ICS = International Continence Society; I-PSS = International Prostate Symptom Score; LUTS = lower urinary tract symptoms; AUA-SI = American Urological Association Symptom Index; SF-12 = Medical Outcomes Study 12-item Short Form Survey; ICIQ-FLUTS = International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms.

Individual prevalence comparisons may be more appropriate than overall prevalence comparisons among studies. LUTS in our study more commonly involved urinary storage problems rather than voiding difficulties, which were also reported for Western studies [6], [7], [14], [17], [18], and [20]. In the EPIC study, the ICS definition of nocturia (two or more voids per night) yielded similar prevalence (24.0%) to ours [7] . However, the prevalence rates for SUI, UUI, or UI reported by the participants in our study were much lower than those in the Western studies (4.5–44%) [5], [17], [18], [21], and [22]. There seem to be ethnic differences. Asian women were less prone to UI or LUTS, which is in line with a global prevalence analysis by Milsom et al [23] and an incidence study by Townsend et al [24] . Some of the differences observed can probably be attributed to methodological differences among studies. However, several racially and ethnically diverse studies also yielded ethnic differences in LUTS prevalence [5], [6], and [21]. These differences may result from many sociocultural and environmental factors, in addition to genetic factors that can affect bladder health, and require further study to distinguish.

4.1. Symptom-specific bother of individual LUTS

Assessment of the bother of symptoms is of key clinical relevance because it relates to both quality-of-life impairment and treatment-seeking [25] . Clinical practice guidelines suggest that only patients reporting bothersome symptoms should be targeted for intervention and that watchful waiting is appropriate for those with minimal symptoms [26] . There is a need to assess the frequency of individual LUTS and their respective bother ratings.

All of the individual LUTS caused bother, and storage symptoms were more likely to cause moderate or severe bother than voiding symptoms, especially urgency or UUI. We found that symptoms and bother did not correspond in a straightforward manner. Nocturia was most frequently rated as bothersome; however, it was primarily rated as no bother or as a minor bother. Urgency and UUI were less frequently rated as bothersome and usually ranked as severe or moderate. This information could assist in targeting patients who need intervention. Our study revealed similar findings to those of Moreira et al [6] , who also noted that urgency was usually associated with moderate or severe bother, whereas nocturia was usually associated with minor bother. Our study is partly in line with those of Coyne et al [27] and Møller et al [28] , who reported that the symptoms most frequently rated bothersome were nocturia, SUI, and urgency [27] and [28], and is similar to a national Finnish study that showed a high burden of urgency and UUI [29] . Because urgency seems to have a more negative impact on patient quality of life, it should be a leading consideration for medical intervention.

4.2. Potential risk factors for LUTS

The pathogenesis of LUTS is not completely understood, but it is considered a multifactorial process. A broader view of LUTS has shown that potential risk factors include age, race, micturition habits, lifestyle factors, and pathologic conditions [30] . We performed a detailed evaluation of potential risk factors for any, individual, and bothersome LUTS, and found that all were influenced by multiple factors. Older age and coexisting POP were both strong predictors for every type of LUTS. Regardless of the number of pregnancies, women who had only cesarean deliveries had no increase in odds for LUTS of any type. Women with multiple vaginal deliveries had increased odds for storage and bothersome LUTS compared with those who had spontaneous vaginal single births, in agreement with prospective studies focusing on reproductive history and progression of LUTS [31] and [32]. Prolonged labor may have a strong influence on any severely bothersome LUTS. Voiding symptoms were less likely to be associated with multiple vaginal deliveries or higher BMI. Multiple vaginal deliveries and prolonged labor may cause repeated injury to the muscles, nerves, and connective tissue of the pelvic floor, and have a negative impact on bladder control. The close relationship between LUTS and POP has rarely been explored. Having either incontinence or prolapse may be associated with an increased risk of developing the other condition [33] . It is possible that women with advanced POP experience more obstructive urinary symptoms, as reported by Rosenzweig et al [34] and Raz et al [35] . Family studies and twin studies have demonstrated that LUTS and POP are both heritable [33] . Our study, however, is cross-sectional, and the risk factors we identified cannot be considered established causes of LUTS. Some of the results should be interpreted with caution.

The strengths of our study are the large representative population-based sample of women and the high response rate. These enabled us to accurately determine the prevalence and bother associated with LUTS. The use of a professional questionnaire for urinary symptoms based strictly on criteria in the 2002 ICS guidelines also enabled us to compare our results with those for other studies.

Our study has some limitations. This analysis was the second of a study conducted 8 yr ago; the prevalence of LUTS may be higher today than at that time. Missing data were not handled well in our study. In addition, our questionnaire did not assess all LUTS, and the cross-sectional design is poor way to ascertain risk factors. Longitudinal studies are needed to better understand the temporal nature and associations with persistence of LUTS.

This was the largest population-based epidemiological study to date of LUTS in adult women. In the 55.5% of adult Chinese women who experienced LUTS, the most prevalent symptoms were nocturia, urgency, and SUI. Urgency and UUI were most frequently reported as moderately or severely bothersome. The likelihood of any, individual, and bothersome LUTS may involve multiple factors, with older age and coexisting POP as strong predictors.

Author contributions: Lan Zhu had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Zhu, Lang.

Acquisition of data: Zhu, Li, Gong, Q. Liu, X. Liu, Zhang.

Analysis and interpretation of data: Zhang, Xu, Zhu.

Drafting of the manuscript: Zhang.

Critical revision of the manuscript for important intellectual content: Zhu, Lang.

Statistical analysis: Zhang, Xu.

Obtaining funding: Zhu, Lang.

Administrative, technical, or material support: None.

Supervision: None.

Other (specify): None.

Financial disclosures: Lan Zhu certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: None.

Funding/Support and role of the sponsor: This study received financial support from the Chinese government under 5-year national project number 3053750. The only role of the sponsor was in approval of the manuscript.

Acknowledgments: We are grateful to the Bristol Urological Institute (Bristol, UK) for authorization of their Female Lower Urinary Tract Symptoms (BFLUTS) questionnaires. We would like to thank Shaomei Han for her professional guidance in data analysis.

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Lower urinary tract symptoms (LUTS) have attracted substantial attention in recent years partly because to their high prevalence but primarily because of heightened awareness of their detrimental impact on health-related quality of life [1] . Studies report that one in five adult women complain about moderate to severe LUTS, and one in ten adults have newly developed LUTS, often along with resulting substantial bother and interference with daily activities [2] and [3]. By 2018, an estimated 2.3 billion people will be affected by at least one LUTS. The prevalence of LUTS is likely to be greater in women than in men. The regional burden of these conditions is estimated to be greatest in Asia [1] . Many large-scale epidemiologic studies of LUTS have been conducted in Western countries, and prevalence estimates reported for LUTS subsets vary widely from 13% to 76% [4] and [5]. This variation could be due to differences in study populations, symptom assessment, data collection, or definitions used [3], [6], and [7]. In China, there have been relatively few epidemiologic studies of LUTS. Several studies have estimated the prevalence of LUTS in Asian countries such as Japan, Korea, and Taiwan [8], [9], and [10]; however, there are notable inconsistencies in the prevalence rates reported across studies, and few were conducted nationwide. In addition, many were limited by bias related to sex, specific LUTS, and age groups.

The aim of this study was to provide estimates of the prevalence and potential risk factors of LUTS and the bother they impose in a nationwide population-based sample of adult women in China.

2.1. Study design and participants

This analysis is the second of a previous study. The data were from a national cross-sectional survey on urinary incontinence (UI) in 20 000 adult women aged ≥20 yr in China. The previous survey included two phases: a pilot study conducted in Beijing, China [11] , and a subsequent nationwide study [12] and [13]. Detailed study procedures and results for stress urinary incontinence (SUI), urgency urinary incontinence (UUI), and mixed urinary incontinence (MUI) have been described in previous reports [11], [12], and [13].

Phase 1 (a pilot survey in Beijing) assessed a representative sample of approximately 5221 respondents (from one urban district and one rural district) who were interviewed face to face by trained interviewers using a standardized questionnaire. The eligibility criteria stipulated women aged ≥20 yr in the general population who had lived in the registered areas for at least 10 yr. We excluded women who were medically diagnosed with cognitive impairment and who could not understand the questions. Detailed study procedures and results were published [11] .

Phase 2 was a nationwide survey conducted between February and July 2006 in six regions of China. The sampling process was multistage and stratified according to geographic region (northwest, southwest, north, east, northeast, and central-south China) and degree of urbanization (large cities and undeveloped economic status were assessed on the basis of the gross domestic product for each province). Eligibility and exclusion criteria were in accord with the pilot survey (on the basis of Chinese population data from 2006). The rationale for the recruitment approach, the study design, and the interpretation of results has been described previously [12] and [13]. Ethics committee approval and written informed consent were obtained.

Our previous study focused on UI, so we recalculated the sample size for this reanalysis according to a previous study conducted in Fuzhou, China, which reported 39.7% prevalence of LUTS in female residents [14] . We aimed to survey at least six age deciles: 20–29, 30–39, 40–49, 50–59, 60–69, and ≥70 yr. A minimal sample size was calculated for detection of 39.7% prevalence of LUTS, with a 5% estimated error and a 95% confidence interval (CI). Considering a 20% refusal rate, a total of 16 805 participants would be required for the LUTS reanalysis according to the formula

FORMULA:

stripin: si1.gif

The sample size was large enough for our reanalysis.

2.2. Diagnostic criteria

The definitions in this study are consistent with the standards recommended by the 2002 International Continence Society (ICS) guidelines [15] . Nocturia is a condition whereby a person awakens at night one or more times to void, and was defined as two or more micturitions per night in our study. Daytime frequency is a condition whereby a patient voids too often by day. In our study, frequency was defined as voiding eight times or more per day. Respondents who reported both UUI and SUI symptoms were classified as having MUI. Those who reported UI without symptoms of UUI or SUI were categorized as having other UI. Women who had given birth to multiple children were defined as having more than one delivery.

2.3. Measurements

We used a modified Bristol Female Lower Urinary Tract Symptoms questionnaire [16] that consisted of two parts. Part 1 included general information about age, marital status, occupation, menopausal status, medically diagnosed disease status, parity, mode of delivery for childbirth, and offspring birth weights. Part 2 was a Chinese version of the International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms (ICIQ-FLUTS). The Chinese version of the questionnaire was translated by survey research experts. To assess the accuracy of the translation, the Chinese version was translated back to English and compared by an independent agent. A pilot study of 40 women was performed before the survey took place to ensure the validity of the questionnaire. The readability of the Chinese version of the questionnaire was at the primary school level.

The questionnaire included an assessment of ten types of LUTS: nocturia, daytime frequency, urgency, UUI, SUI, other incontinence, pain or burning, hesitancy, straining, and intermittency. Participants were asked to rate how often individual LUTS were experienced during the previous 4 wk and, if LUTS were experienced, to what degree the symptoms were bothersome. All subjects reporting LUTS were asked to describe the frequency of the symptoms. Nocturia was measured as the number of micturitions per night, and frequency was defined as eight or more times per day. The other symptoms were measured according to how long participants had experienced them in the previous 4 wk, classified as: no (never); <10 d (occasionally); 10–20 d (sometimes); 20 d (most of the time); or every day (all of the time). The prevalence of other LUTS was defined as answers other than no. The bother associated with each symptom was evaluated using a scale ranging from 0 (not bothered at all) to 10 (greatly bothered). Bother was also defined by dividing the Likert responses into three groups: minor (rated 1–4), moderate (rated 5–7), and severe (rated 8–10). Detailed information on sociodemographic background, reproductive factors, defecation, and medical conditions was also collected. The interviewers underwent standardized training and regular quality control checks.

2.4. Statistical analysis

The data were finally stratified into eight age deciles. We performed χ2 tests to compare prevalence differences between groups. Receiver operating characteristic (ROC) curve distribution was used to assess the number of deliveries and their relationship to LUTS with moderate or severe bother. A multivariate model was set up to assess bother and individual LUTS-related potential risk factors and to estimate odds ratios and 95% CIs; this model was adapted for all factors in the final version. A two-sided p value ≤0.05 was considered for statistical significance. EpiData software ( http://www.epidata.dk/ ) was used for data entry and error detection. SPSS v.12.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis.

As shown in Figure 1 , 976 (4.88%) of the questionnaires could not be evaluated and were excluded in the previous UI study; 32 participants were further excluded because of missing information regarding reproductive factors or LUTS symptoms. A total of 18 992 participants (94.96%) were entered into our data analyses. The age distribution ranged from 20 to 99 yr, with a mean of 44.9 yr (±15.9 yr) (the age distribution in our study was similar to the total adult population in the 2006 National Census). Overall, 438 participants (2.3%) were from minority groups. The numbers of participants from urban and rural areas were equal (50% vs 50%). Table 1 lists the sociodemographic characteristics of the participants.

gr1

Fig. 1 Study flowchart. UI = urinary incontinence; LUTS = lower urinary tract symptoms.

Table 1 Characteristics of the 18 992 subjects interviewed

Characteristic Data
Mean age, yr (SD) 44.91 (15.9)
Age, n (%)
 20–29 yr 3381 (17.8)
 30–39 yr 4778 (25.2)
 40–49 yr 4199 (22.1)
 50–59 yr 2881 (15.2)
 60–69 yr 2029 (10.7)
 70–79 yr 1194 (6.3)
 80–89 yr 442 (2.3)
 ≥90 yr 88 (0.5)
Residence, n (%)
 Urban 9490 (50.0)
 Rural 9502 (50.0)
Current marital status, n (%)
 Single, never married 1392 (7.3)
 Married 15 976 (84.1)
 Remarried 178 (0.9)
 Divorced/separated 77 (0.4)
 Widowed 1369 (7.2)
Mean body mass index, kg/m2 (SD) 23.4 (3.8)
Body mass index, n (%)
 Underweight (<18.5 kg/m2) 1140 (6.0)
 Normal (18.5–23.9 kg/m2) 10 370 (54.6)
 Overweight (24–27.9 kg/m2) 5480 (28.9)
 Obese (≥28 kg/m2) 2002 (10.5)
Median parity, pregnancies (range) 1 (0–10)
Parity, n (%)
 Nulliparous 2251 (11.9)
 Primiparous (=1) 8980 (47.3)
 Multiparous (=2) 4286 (22.6)
 Multiparous (≥3) 3475 (18.3)
Job, n (%)
 Manual labor 4343 (22.9)
 Intellectual labor 14 649 (77.1)
Race, n (%)
 Han 18 554 (97.7)
 Minority 438 (2.3)

3.1. Prevalence of LUTS

The frequencies of individual LUTS are shown in Table 2 . The prevalence of any LUTS was 55.5% and increased with age. Storage symptoms were more common than voiding symptoms (53.9% vs 12.9%). Nocturia was the most common symptom (23.4%), followed by urgency (23.3%) and SUI (18.9%); incontinence was also highly prevalent (31.9%). Straining was the least common symptom (3.3%; Table 2 ).

Table 2 Prevalence of individual lower urinary tract symptoms by age and residence

  Symptoms, n (%)
  Total Age group Residence
  (n = 18 992) 20–29 yr 30–39 yr 40–49 yr 50–59 yr 60–69 yr 70–79 yr 80–90 yr ≥90 yr p value b Urban Rural p value b
    (n = 3381) (n = 4778) (n = 4199) (n = 2881) (n = 2029) (n = 1194) (n = 442) (n = 88)   (n = 9490) (n = 9502)  
Nocturia
 ≥2 times/night 4450 (23.4) 302 (8.9) 542 (11.3) 745 (17.7) 900 (31.2) 891 (43.9) 715 (59.9) 289 (65.4) 66 (75.0) <0.001 2161 (22.8) 2289 (24.1) 0.032
Frequency 3290 (17.3) 438 (13.0) 654 (13.7) 666 (15.9) 583 (20.2) 454 (22.4) 329 (27.6) 133 (30.1) 33 (37.5) <0.001 1934 (20.4) 1356 (14.3) <0.001
Urgency 4430 (23.3) 399 (11.8) 774 (16.2) 966 (23.0) 847 (29.4) 655 (32.3) 503 (42.1) 237 (53.6) 49 (55.7) <0.001 2361 (24.9) 2069 (21.8) <0.001
UI
 Any UI 6052 (31.9) 362 (10.7) 948 (19.8) 1488 (35.4) 1316 (45.7) 990 (48.8) 643 (53.9) 247 (55.9) 58 (65.9) <0.001 2733 (28.8) 3319 (34.9) <0.001
 UUI 488 (2.6) 35 (1.0) 73 (1.5) 84 (2.0) 81 (2.8) 94 (4.6) 97 (8.1) 23 (5.2) 1 (1.1) <0.001 272 (2.9) 216 (2.3) 0.01
 SUI 3,592 (18.9) 178 (5.3) 659 (13.8) 993 (23.6) 812 (28.2) 556 (27.4) 286 (24.0) 85 (19.2) 23 (26.1) <0.001 1555 (16.4) 2037 (21.4) <0.001
 MUI 1,788 (9.4) 43 (1.3) 206 (4.3) 398 (9.5) 405 (14.1) 320 (15.8) 247 (20.7) 136 (30.8) 33 (37.5) <0.001 752 (7.9) 1036 (10.9) <0.001
Other UI 858 (4.5) 123 (3.6) 71 (1.5) 138 (3.3) 174 (6.0) 145 (7.1) 134 (11.2) 52 (11.8) 21 (23.9) <0.001 468 (4.9) 390 (4.1) 0.006
 Any involuntary a 536 (2.8) 13 (0.4) 50 (1.0) 95 (2.3) 110 (3.8) 100 (4.9) 102 (8.5) 45 (10.2) 21 (23.9) <0.001 235 (2.5) 301 (3.2) 0.004
 Nocturnal enuresis 172 (0.9) 10 (0.3) 12 (0.3) 27 (0.6) 30 (1.0) 25 (1.2) 40 (3.4) 19 (4.3) 9 (10.2) <0.001 105 (1.1) 67 (0.7) 0.004
 During intercourse a 336 (2.0) 110 (3.7) 30 (0.6) 53 (1.3) 72 (2.8) 42 (3.0) 27 (4.2) 2 (1.1) 0 <0.001 227 (2.7) 109 (1.3) <0.001
Pain/burning 854 (4.5) 71 (2.1) 175 (3.7) 208 (5.0) 167 (5.8) 130 (6.4) 65 (5.4) 29 (6.6) 9 (10.2) <0.001 374 (3.9) 480 (5.1) <0.001
Hesitancy 1072 (5.6) 137 (4.1) 171 (3.6) 167 (4.0) 200 (6.9) 155 (7.6) 152 (12.7) 71 (16.1) 19 (21.6) <0.001 675 (7.1) 397 (4.2) <0.001
Straining 626 (3.3) 39 (1.2) 87 (1.8) 117 (2.8) 110 (3.8) 110 (5.4) 101 (8.5) 44 (10.0) 18 (20.5) <0.001 378 (4.0) 248 (2.6) <0.001
Intermittency 1346 (7.1) 110 (3.3) 211 (4.4) 231 (5.5) 259 (9.0) 233 (11.5) 197 (16.5) 83 (18.8) 22 (25.0) <0.001 801 (8.4) 545 (5.7) <0.001
Storage symptoms 10 245 (53.9) 1117 (33.0) 1930 (40.4) 2299 (54.8) 1956 (67.9) 1500 (73.9) 987 (82.7) 375 (84.8) 81 (92.0) <0.001 5249 (55.3) 4996 (52.6) <0.001
Voiding symptoms 2444 (12.9) 249 (7.4) 452 (9.5) 475 (11.3) 461 (16.0) 393 (19.4) 271 (22.7) 113 (25.6) 30 (34.1) <0.001 1353 (14.3) 1091 (11.5) <0.001
Any LUTS 10 540 (55.5) 1185 (35.0) 2034 (42.6) 2360 (56.2) 1988 (69.0) 1521 (75.0) 992 (83.1) 378 (85.5) 82 (93.2) <0.001 5420 (57.1) 5120 (53.9) <0.001

a 16 695 women were sexually active and included in the category UI during sexual intercourse. The category Any involuntary represents women who reported leaking for no reason or any involuntary loss of urine.

b The Pearson χ2 test was used to compare differences in the prevalence of individual LUTS by age and residence.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence.

A notable age-related trend was observed for the prevalence of any LUTS, storage, or voiding symptoms, with approximately 50% greater prevalence observed for the oldest compared to the youngest participants ( Table 2 ; Fig 2 and Fig 3). UI was frequent in women aged ≤70 yr, but nocturia was more prevalent in those aged ≥70 yr. Urgency was usually reported by women aged ≤50 yr. Frequency, urgency, hesitancy, straining, and intermittency were more common in urban women (p < 0.001). Rural women experienced more nocturia (22.8% vs 24.1%; p = 0.032). UI was the most common symptom (28.8% vs 34.9%; p < 0.001) in both areas, but particularly in rural areas ( Fig. 3 ).

gr2

Fig. 2 Age-specific prevalence of lower urinary tract symptom subtypes. UI = urinary incontinence.

gr3

Fig. 3 Urban and rural prevalence differences for individual lower urinary tract symptoms. UI = urinary incontinence.

3.2. Symptom-specific bother of LUTS

The extent to which study participants were bothered by each urinary symptom is summarized in Table 3 and Fig. 4 . We found that no bother or minor bother were the most common responses reported for every symptom. Only 14.6–29.9% of participants with bothersome LUTS reported a moderate to severe impact on their quality of life; 4.2–11.5% reported severe bother. Some of the most prevalent symptoms were among those least commonly reported as bothersome, such as SUI (67.4%). Some of the most likely to be rated as bothersome were not necessarily the most likely to cause moderate or severe bother, such as nocturia (19.5%). Urgency was among the least likely to cause bother but was the symptom most likely to cause severe (11.5%) or moderate to severe bother (29.9%), followed by UUI (10.8% and 27.6%, respectively). Frequency was the storage symptom that was least commonly reported as causing moderate or severe bother (14.6%).

Table 3 Self-reported bother related to individual lower urinary tract symptoms

Bother Symptoms, n (%)
  Nocturia Frequency Urgency UUI a SUI Pain/burning Hesitancy Straining Intermittency
Likert score
 0 14 854 (78.21) 17 090 (89.99) 16 242 (85.52) 17 245 (90.80) 15 366 (80.91) 18 270 (96.20) 18 333 (96.53) 18 527 (97.55) 18 136 (95.49)
 1 1505 (7.92) 818 (4.31) 771 (4.06) 534 (2.81) 1302 (6.86) 285 (1.50) 271 (1.43) 156 (0.82) 284 (1.50)
 2 879 (4.63) 426 (2.24) 553 (2.91) 329 (1.73) 868 (4.57) 173 (0.91) 140 (0.74) 114 (0.60) 200 (1.05)
 3 625 (3.29) 271 (1.43) 403 (2.12) 277 (1.46) 540 (2.84) 97 (0.51) 100 (0.53) 64 (0.34) 136 (0.72)
 4 322 (1.70) 110 (0.58) 200 (1.05) 126 (0.66) 269 (1.42) 56 (0.29) 46 (0.24) 32 (0.17) 75 (0.39)
 5 284 (1.50) 94 (0.49) 256 (1.35) 149 (0.78) 247 (1.30) 47 (0.25) 34 (0.18) 34 (0.18) 58 (0.31)
 6 141 (0.74) 67 (0.35) 149 (0.78) 97 (0.51) 108 (0.57) 16 (0.08) 24 (0.13) 24 (0.13) 35 (0.18)
 7 133 (0.70) 36 (0.19) 103 (0.54) 46 (0.24) 80 (0.42) 11 (0.06) 12 (0.06) 7 (0.04) 17 (0.09)
 8 137 (0.72) 41 (0.22) 147 (0.77) 86 (0.45) 85 (0.45) 20 (0.11) 12 (0.06) 16 (0.08) 25 (0.13)
 9 112 (0.59) 39 (0.21) 168 (0.88) 103 (0.54) 127 (0.67) 17 (0.09) 20 (0.11) 18 (0.09) 26 (0.14)
 10 0 0 0 0 0 0 0 0 0
Any bother b 4138 1902 2750 1747 3626 722 659 465 856
Moderate to severe bother 807 (19.50) 277 (14.56) 823 (29.93) 483 (27.60) 647 (17.84) 111 (15.37) 102 (15.48) 99 (21.29) 161 (18.81)
Any severe bother 249 (6.02) 80 (4.21) 315 (11.45) 189 (10.80) 212 (5.85) 37 (5.12) 32 (4.86) 34 (7.31) 51 (5.96)
Any LUTS 4450 3290 4430 2276 5380 854 1072 626 1346
Bother rate (%) 92.99 57.81 62.08 76.78 67.40 84.54 61.47 74.28 63.60

a SUI and UUI include participants with mixed urinary incontinence.

b Any bother: participants reported that they were bothered by at least one individual LUTS.

UUI = urgency urinary incontinence; SUI = stress urinary incontinence; LUTS = lower urinary tract symptoms.

gr4

Fig. 4 Symptom-specific bother and extent of individual lower urinary tract symptoms. Bother was also defined by dividing the Likert responses into three groups: (a) 1–4, minor; (b) 5–7, moderate; and (c) 8–10, severe. UUI = urgency urinary incontinence; SUI = stress urinary incontinence.

Voiding symptoms were less likely to cause moderate or severe bother than storage symptoms (p < 0.001). Pain or burning was the second most frequent bother (84.5%), but straining and intermittency were more likely to cause moderate or severe bother (21.3% and 18.8%, respectively; Table 3 ).

3.3. Potential risk factors for LUTS

Risk factors for LUTS according to logistic regression analysis are shown in Table 4, Table 5, and Table 6. We identified multiple risk factors for any, individual, and bothersome LUTS; older age, postmenopausal status, constipation, and coexisting pelvic organ prolapse (POP) increased the odds for every type of LUTS. Older age and coexisting POP were both strong predictors (p ≤ 0.05). In comparison with spontaneous vaginal single births, our study showed a higher risk of storage and moderate or severe bothersome LUTS in women with multiple vaginal deliveries (1.46-fold and 1.26-fold, respectively) and instrumental deliveries (1.25-fold and 1.22-fold, respectively). ROC distributions showed that multiple deliveries were more closely related to any severely bothersome LUTS ( Fig. 5 ). Women who had single or multiple deliveries via cesarean section had no increase in odds for every LUTS (p > 0.05), as did women who had spontaneous vaginal single births. Participants with histories of prolonged labor and perineal laceration had increased odds for moderate or severe bothersome LUTS; prolonged labor may have a stronger influence (1.99-fold, with adjustment for all other factors). Voiding symptoms were less influenced by delivery histories. Lifestyle factors and pathologic conditions such as higher body mass index (BMI), hypertension, diabetes, alcohol consumption, and smoking had various effects on any, individual, and bothersome LUTS (Table 4, Table 5, and Table 6).

Table 4 Multivariate analyses of associations between patient characteristics and bothersome lower urinary tract symptoms

  n (%) Any LUTS bother (n = 6950) Moderate to severe LUTS bother (n = 1695) Any severe LUTS bother (n = 652)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted OR a 95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) <0.001 1.43 1.26, 1.63 0.078 1.29 0.97, 1.71 0.072 1.63 0.96, 2.79
 40–49 yr 4199 (22.1) <0.001 1.85 1.62, 2.12 <0.001 2.04 1.54, 2.69 <0.001 2.91 1.73, 4.90
 50–59 yr 2881 (15.2) <0.001 2.08 1.75, 2.47 <0.001 2.71 1.96, 3.74 <0.001 4.99 2.83, 8.80
 60–69 yr 2029 (10.7) <0.001 2.12 1.73, 2.60 <0.001 2.29 1.60, 3.28 <0.001 4.45 2.41, 8.20
 70–79 yr 1194 (6.3) <0.001 2.75 2.21, 3.43 <0.001 2.70 1.86, 3.91 <0.001 5.16 2.77, 9.64
 80–89 442 (2.3) <0.001 3.59 2.74, 4.71 <0.001 3.58 2.39, 5.37 <0.001 6.59 3.40, 12.78
  ≥90 yr 88 (0.5) <0.001 9.24 5.19, 16.47 <0.001 7.30 4.18, 12.77 <0.001 16.56 7.59, 36.10
Residence   <0.001     0.109     0.846    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.16 1.08, 1.24   1.10 0.98, 1.23   1.02 0.86, 1.21
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.66 1.49, 1.86 <0.001 1.79 1.48, 2.15 <0.001 2.26 1.68, 3.02
 Postmenopausal status 6178 (32.5) <0.001 1.55 1.35, 1.77 <0.001 1.55 1.25, 1.92 0.016 1.51 1.08, 2.12
Body mass index   <0.001     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.425 1.06 0.91, 1.24 0.008 1.41 1.09, 1.81 0.844 0.96 0.60, 1.51
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.16 1.08, 1.25 <0.001 1.29 1.15, 1.46 0.001 1.38 1.14, 1.66
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.47 1.27, 1.71 <0.001 1.70 1.37, 2.10 <0.001 1.81 1.33, 2.48
Mode of delivery   <0.001     0.001     0.006    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.25 1.14, 1.36 0.002 1.26 1.09, 1.46 0.001 1.51 1.20, 1.92
 Forceps or vacuum delivery 746 (3.9) 0.026 1.20 1.02, 1.42 0.134 1.22 0.94, 1.58 0.240 1.29 0.85, 1.96
 Cesarean section                    
  1 2,399 (12.6) 0.001 0.83 0.75, 0.93 0.095 0.83 0.67, 1.03 0.502 0.87 0.59, 1.30
  ≥2 55 (3.0) 0.965 1.01 0.58, 1.77 0.401 1.42 0.63, 3.23 0.356 1.76 0.53, 5.83
 Nulliparity 2251 (11.9) <0.001 0.64 0.55, 0.74 0.050 0.74 0.54, 1.00 0.090 1.50 0.94, 2.41
Prolonged labor b   <0.001     <0.001     <0.001    
 No (ref.) 13 444 (95.7)   1.00     1.00     1.00  
 Yes 599 (4.3)   1.62 1.35, 1.94   1.99 1.58, 2.50   2.19 1.58, 3.02
Perineal laceration b   <0.001     0.018     0.700    
 No (ref.) 10 312 (77.0)   1.00 -   1.00     1.00  
 Yes 3088 (23.0)   1.22 1.12, 1.33   1.17 1.03, 1.34   1.04 0.85, 1.04
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.97 1.79, 2.16   2.22 1.95, 2.52   2.28 1.89, 2.76
Hormone replacement therapy   0.009     0.510     0.879    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.69 0.52, 0.91   1.17 0.74, 1.84   0.95 0.50, 1.82
Pelvic organ prolapse   <0.001     <0.001     0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.08 1.55, 2.77   2.29 1.65, 3.18   2.12 1.35, 3.35
Hypertension   <0.001     <0.001     0.017    
 Nonexistent (ref.) 17 093 (90.0)   1.00 -   1.00     1.00  
 Present 1899 (10.0)   1.48 1.33, 1.65   1.49 1.29, 1.72   1.29 1.05, 1.60
Diabetes   0.001     0.001     0.011    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.38 1.14, 1.67   1.48 1.18, 1.86   1.52 1.10, 2.10
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.25 1.11, 1.39   1.54 1.28, 1.85   2.10 1.56, 2.78
Alcohol consumption   <0.001     0.466     0.168    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.37 1.23, 1.52   1.07 0.90, 1.27   1.20 0.93, 1.56

a The adjusted odds ratios with 95% confidence intervals are presented. All of the factors, except for prolonged labor and perineal laceration, were adjusted in the multivariate model. For prolonged labor and perineal laceration, the other factors were adjusted. Pelvic organ prolapse, hypertension, and diabetes were defined according to hospital diagnosis.

b There were some missing data for prolonged labor (244) and perineal laceration (887) because the participants could not accurately recall these histories.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 5 Multivariate analyses of associations between patient characteristics and the presence of storage, voiding, and incontinence lower urinary tract symptoms

  n (%) Storage symptoms (n = 10 245) Voiding symptoms (n = 2444) Any urinary incontinence (n = 6052)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.001 1.21 1.09, 1.36 0.001 1.38 1.14, 1.67 <0.001 1.55 1.34, 1.80
 40–49 yr 4199 (22.1) <0.001 1.75 1.56, 1.98 0.001 1.42 1.16, 1.74 <0.001 2.66 2.29, 3.10
 50–59 yr 2881 (15.2) <0.001 2.00 1.70, 2.36 <0.001 1.57 1.22, 2.01 <0.001 2.80 2.32, 3.38
 60–69 yr 2029 (10.7) <0.001 2.01 1.64, 2.47 0.001 1.63 1.22, 2.18 <0.001 2.46 1.98, 3.06
 70–79 yr 1194 (6.3) <0.001 3.30 2.61, 4.17 <0.001 1.84 1.36, 2.48 <0.001 3.02 2.39, 3.81
 80–89 442 (2.3) <0.001 3.93 2.86, 5.39 <0.001 2.03 1.44, 2.86 <0.001 3.32 2.52, 4.37
 ≥90 yr 88 (0.5) <0.001 9.14 4.11, 20.29 <0.001 2.98 1.75, 5.05 <0.001 5.87 3.58, 9.65
Residence   <0.001     <0.001     0.006    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.35 1.26, 1.45   1.32 1.19, 1.45   0.90 0.84, 0.97
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.55 1.39, 1.73 <0.001 1.75 1.50, 2.05 <0.001 1.61 1.43, 1.81
 Postmenopausal status 6178 (32.5) <0.001 1.63 1.42, 1.87 <0.001 1.50 1.24, 1.82 <0.001 1.44 1.26, 1.65
Body mass index   <0.001     0.204     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.445 1.05 0.92, 1.21 0.138 0.85 0.68, 1.06 0.137 0.88 0.74, 1.04
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.31 1.23, 1.41 0.839 0.99 0.90, 1.09 <0.001 1.34 1.25, 1.45
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.87 1.59, 2.21 0.180 1.14 0.94, 1.39 <0.001 1.77 1.52, 2.06
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.46 1.34, 1.60 <0.001 1.31 1.15, 1.49 <0.001 1.63 1.49, 1.79
 Forceps or vacuum delivery 746 (3.9) 0.007 1.25 1.06, 1.48 0.002 1.41 1.14, 1.75 <0.001 1.35 1.14, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.044 0.90 0.82, 1.00 0.590 0.96 0.81, 1.12 <0.001 0.72 0.63, 0.81
  ≥2 55 (3.0) 0.234 0.71 0.41, 1.25 0.513 1.30 0.60, 2.83 0.247 0.69 0.37, 1.29
 Nulliparity 2251 (11.9) 0.042 0.88 0.77, 1.00 0.293 1.12 0.91, 1.37 <0.001 0.71 0.59, 0.84
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.77 1.60, 1.95   2.18 1.95, 2.43   1.87 1.70, 2.06
Hormone replacement therapy   0.050     0.001     0.211    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.75 0.56, 1.00   0.58 0.41, 0.81   0.83 0.63, 1.11
Pelvic organ prolapse   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.38 1.68, 3.36   2.35 1.72, 3.21   1.96 1.47, 2.60
Hypertension   <0.001     0.202     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.41 1.24, 1.61   1.09 0.95, 1.25   1.29 1.16, 1.44
Diabetes   0.001     <0.001     0.114    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.49 1.17, 1.89   1.61 1.31, 1.99   1.17 0.96, 1.41
Smoking   <0.001     <0.001     0.306    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.31 1.17, 1.46   1.70 1.46, 1.98   1.06 0.95, 1.20
Alcohol consumption   <0.001     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.22 1.10, 1.35   1.37 1.18, 1.59   1.51 1.35, 1.68

a All of the factors were adjusted.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 6 Multivariate analyses of the association between patient characteristics and individual LUTS and any LUTS with adjustment for all factors

  n (%) Nocturia (n = 4450) Frequency (n = 3290) Urgency (n = 4430)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.598 0.96 0.81, 1.13 0.013 1.22 1.04, 1.42 <0.001 1.56 1.33, 1.82
 40–49 yr 4199 (22.1) 0.002 1.30 1.10, 1.54 <0.001 1.44 1.22, 1.70 <0.001 2.07 1.76, 2.43
 50–59 yr 2881 (15.2) <0.001 1.84 1.50, 2.26 <0.001 1.58 1.27, 1.95 <0.001 2.20 1.80, 2.69
 60–69 yr 2029 (10.7) <0.001 2.63 2.08, 3.32 <0.001 1.72 1.34, 2.21 <0.001 2.05 1.62, 2.60
 70–79 yr 1194 (6.3) <0.001 5.13 4.00, 6.57 <0.001 2.26 1.74, 2.94 <0.001 3.03 2.37, 3.88
 80–89 442 (2.3) <0.001 7.08 5.29, 9.48 <0.001 2.59 1.91, 3.52 <0.001 4.66 3.49, 6.21
 ≥90 yr 88 (0.5) <0.001 12.95 7.60, 22.06 <0.001 3.47 2.13, 5.67 <0.001 5.19 3.19, 8.45
Residence   0.692     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   0.98 0.91, 1.07   1.45 1.33, 1.58   1.29 1.19, 1.39
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.43 1.25, 1.64 <0.001 1.42 1.24, 1.63 <0.001 1.41 1.24, 1.61
 Postmenopausal status 6178 (32.5) <0.001 1.57 1.35, 1.83 <0.001 1.52 1.28, 1.81 <0.001 1.35 1.16, 1.57
Body mass index   <0.001     0.055     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.133 1.15 0.96, 1.39 0.611 1.05 0.88, 1.24 0.844 1.02 0.85, 1.12
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.46 1.35, 1.59 0.392 1.04 0.95, 1.13 <0.001 1.24 1.14, 1.34
 Obese (≥28 g/m2) 2002 (10.5) <0.001 2.16 1.84, 2.54 0.006 1.28 1.07, 1.53 <0.001 1.56 1.33, 1.83
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.037 1.12 1.01, 1.24 0.002 0.83 0.74, 0.93 0.000 1.41 1.27, 1.57
 Forceps or vacuum delivery 746 (3.9) 0.685 1.04 0.86, 1.26 0.372 1.09 0.90, 1.33 0.002 1.34 1.11, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.707 0.97 0.85, 1.12 0.212 1.09 0.95, 1.24 0.132 1.10 0.97, 1.25
  ≥2 55 (3.0) 0.600 1.18 0.63, 2.20 0.247 0.62 0.28, 1.39 0.567 0.81 0.40, 1.66
 Nulliparity 2251 (11.9) <0.001 0.59 0.49, 0.72 0.004 1.28 1.08, 1.51 0.020 1.22 1.03, 1.44
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.52 1.37, 1.69   1.26 1.13, 1.40   1.84 1.66, 2.02
Hormone replacement therapy   0.039     0.388     0.009    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.73 0.54, 0.98   1.17 0.82, 1.66   0.67 0.50, 0.91
Pelvic organ prolapse   0.002     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   1.62 1.20, 2.17   1.78 1.32, 2.41   2.00 1.51, 2.67
Hypertension   <0.001     0.075     0.112    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.48 1.32, 1.65   1.12 0.99, 1.27   1.10 0.98, 1.23
Diabetes   <0.001     0.084     0.049    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.73 1.42, 2.10   1.20 0.98, 1.48   1.21 1.00, 1.47
Smoking   0.047     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.15 1.00, 1.33   0.59 0.52, 0.68   2.20 1.94, 2.49
Alcohol consumption   0.004     0.133     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   0.82 0.72, 0.94   1.10 0.97, 1.24   1.29 1.14, 1.45
  n (%) UUI (n = 488) SUI (n = 3592) MUI (n = 1788)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.017 1.77 1.11, 2.83 <0.001 1.78 1.47, 2.15 <0.001 2.28 1.59, 3.26
 40–49 yr 4199 (22.1) 0.003 2.08 1.28, 3.38 <0.001 2.74 2.26, 3.31 <0.001 4.09 2.88, 5.82
 50–59 yr 2881 (15.2) 0.022 1.99 1.10, 3.58 <0.001 2.62 2.09, 3.29 <0.001 4.94 3.36, 7.26
 60–69 yr 2029 (10.7) 0.001 2.83 1.49, 5.38 <0.001 2.21 1.71, 2.86 <0.001 4.57 3.01, 6.93
 70–79 yr 1194 (6.3) 0.000 5.03 2.64, 9.57 <0.001 1.87 1.42, 2.46 <0.001 6.40 4.18, 9.79
 80–89 442 (2.3) 0.003 3.00 1.45, 6.24 0.040 1.43 1.02, 2.00 <0.001 11.15 7.13, 17.44
 ≥90 yr 88 (0.5) 0.624 0.60 0.08 4.68 0.001 2.41 1.41, 4.14 <0.001 17.01 9.34, 30.95
Residence   0.022     0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.26 1.03, 1.53   0.87 0.80, 0.95   0.81 0.72, 0.90
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.89 1.34, 2.67 <0.001 1.37 1.20, 1.57 <0.001 1.69 1.40, 2.03
 Postmenopausal status 6178 (32.5) 0.004 1.86 1.22, 2.84 <0.001 1.33 1.15, 1.55 0.077 1.21 0.98, 1.49
Body mass index   0.454     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.706 1.09 0.70, 1.69 0.39 0.91 0.73, 1.13 0.001 0.56 0.40, 0.79
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.214 1.14 0.93, 1.40 <0.001 1.35 1.24, 1.47 0.058 1.12 1.00, 1.26
 Obese (≥28 g/m2) 2002 (10.5) 0.157 1.31 0.90, 1.91 <0.001 1.42 1.20, 1.68 <0.001 1.60 1.31, 1.96
Mode of delivery   0.182     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.176 1.21 0.92, 1.60 <0.001 1.25 1.12, 1.38 <0.001 1.85 1.60, 2.15
 Forceps or vacuum delivery 746 (3.9) 0.801 0.94 0.56, 1.57 0.007 1.28 1.07, 1.54 0.014 1.39 1.07, 1.81
 Cesarean section                    
  1 2,399 (12.6) 0.045 1.42 1.01, 2.01 <0.001 0.66 0.57, 0.77 0.257 0.88 0.70, 1.10
  ≥2 55 (3.0) 0.997 * * 0.544 0.81 0.40, 1.62 0.843 0.90 0.32, 2.55
 Nulliparity 2251 (11.9) 0.040 1.61 1.02, 2.54 <0.001 0.34 0.26, 0.44 0.004 0.56 0.38, 0.83
Constipation   0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.49 1.18, 1.88   1.28 1.15, 1.42   2.15 1.89, 2.45
Hormone replacement therapy   0.075     0.883     0.143    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.57 0.30, 1.06   1.03 0.74, 1.42   0.74 0.50, 1.11
Pelvic organ prolapse   0.001     0.050     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.40 1.41, 4.06   1.36 1.01, 1.86   2.31 1.66, 3.21
Hypertension   0.390     0.004     0.067    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.12 0.87, 1.44   1.19 1.06, 1.34   1.14 0.99, 1.32
Diabetes   0.564     0.030     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.12 0.76, 1.67   0.79 0.64, 0.98   1.54 1.23, 1.93
Smoking   0.755     0.084     0.927    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.05 0.76, 1.47   1.13 0.98, 1.29   1.01 0.84, 1.21
Alcohol consumption   0.906     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.02 0.75, 1.02   1.34 1.18, 1.52   1.54 1.30, 1.83
  n (%) Other UI (n = 858) Pain/burning (n = 854) Hesitancy (n = 1072)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     0.016     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.007 0.63 0.45, 0.88 0.010 1.52 1.11, 2.09 0.912 1.02 0.78, 1.33
 40–49 yr 4199 (22.1) 0.108 1.31 0.94, 1.81 0.001 1.75 1.26, 2.43 0.898 0.98 0.74, 1.31
 50–59 yr 2881 (15.2) 0.003 1.82 1.22, 2.72 0.015 1.65 1.10, 2.45 0.136 1.31 0.92, 1.87
 60–69 yr 2029 (10.7) 0.008 1.84 1.17, 2.89 0.062 1.55 0.98, 2.45 0.334 1.23 0.81, 1.86
 70–79 yr 1194 (6.3) <0.001 2.85 1.81, 4.51 0.503 1.19 0.72, 1.95 0.002 1.95 1.28, 2.98
 80–89 442 (2.3) <0.001 2.88 1.74, 4.76 0.317 1.34 0.76, 2.37 <0.001 2.43 1.53, 3.85
 ≥90 yr 88 (0.5) <0.001 6.18 3.26, 11.72 0.089 2.04 0.90, 4.64 <0.001 3.25 1.70, 6.21
Residence   0.143     0.021     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.12 0.96, 1.30   0.83 0.71, 0.97   1.64 1.42, 1.89
Menstrual condition   0.007     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) 0.010 1.43 1.09, 1.89 <0.001 1.90 1.51, 2.39 <0.001 1.72 1.36, 2.18
 Postmenopausal status 6178 (32.5) 0.010 1.51 1.11, 2.06 0.042 1.35 1.01, 1.81 0.002 1.57 1.18, 2.08
Body mass index   0.298     0.643     0.537    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.300 1.18 0.87, 1.60 0.555 0.89 0.62, 1.30 0.187 0.81 0.59, 1.11
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.079 1.16 0.98, 1.36 0.218 0.91 0.78, 1.06 0.701 0.97 0.84, 1.12
 Obese (≥28 g/m2) 2002 (10.5) 0.312 1.17 0.86, 1.59 0.796 0.96 0.70, 1.31 0.669 1.06 0.81, 1.40
Mode of delivery   <0.001     <0.001     0.086    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.213 1.15 0.93, 1.42 <0.001 1.59 1.30, 1.94 0.785 1.03 0.85, 1.25
 Forceps or vacuum delivery 746 (3.9) 0.657 1.09 0.75, 1.60 0.030 1.47 1.04, 2.07 0.024 1.40 1.05, 1.88
 Cesarean section                    
  1 2399 (12.6) 0.654 0.93 0.68, 1.27 0.104 1.23 0.96, 1.57 0.373 0.90 0.71, 1.14
  ≥2 55 (3.0) 0.681 1.28 0.39, 4.20 0.230 1.90 0.67, 5.40 0.555 0.65 0.15, 2.75
 Nulliparity 2251 (11.9) <0.001 2.40 1.77, 3.26 0.184 0.77 0.53, 1.13 0.170 1.21 0.92, 1.60
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.87 1.57, 2.22   2.18 1.84, 2.57   2.11 1.82, 2.45
Hormone replacement therapy   0.859     0.497     0.071    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   1.06 0.57, 1.97   1.27 0.64, 2.50   0.65 0.40, 1.04
Pelvic organ prolapse   <0.001     0.026     0.012    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.65 1.76, 4.00   1.74 1.07, 2.84   1.81 1.14, 2.88
Hypertension   0.206     0.284     0.022    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.14 0.93, 1.39   0.89 0.71, 1.11   1.24 1.03, 1.48
Diabetes   0.017     0.041     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.44 1.07, 1.93   1.41 1.01, 1.95   1.61 1.24, 2.10
Smoking   0.267     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.16 0.90, 1.50   2.16 1.68, 2.78   1.70 1.70, 2.65
Alcohol consumption   0.846     0.119     0.013    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.03 0.80, 1.31   1.22 0.95, 1.56   1.33 1.06, 1.66
  n (%) Straining (n = 626) Intermittency (n = 1346) Any LUTS (n = 10 540)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.006 1.84 1.19, 2.84 0.003 1.51 1.15, 1.99 <0.001 1.22 1.09, 1.36
 40–49 yr 4199 (22.1) <0.001 2.45 1.57, 3.81 0.001 1.65 1.24, 2.20 <0.001 1.71 1.51, 1.92
 50–59 yr 2881 (15.2) <0.001 2.64 1.57, 4.43 <0.001 2.08 1.48, 2.92 <0.001 1.91 1.62, 2.25
 60–69 yr 2029 (10.7) <0.001 3.29 1.85, 5.85 <0.001 2.27 1.54, 3.34 <0.001 1.92 1.56, 2.35
 70–79 yr 1194 (6.3) <0.001 4.72 2.63, 8.47 <0.001 3.22 2.17, 4.78 <0.001 3.05 2.41, 3.86
 80–89 442 (2.3) <0.001 5.31 2.84, 9.93 <0.001 3.66 2.37, 5.63 <0.001 3.71 2.69, 5.12
 ≥90 yr 88 (0.5) <0.001 11.61 5.45, 24.73 <0.001 5.05 2.75, 9.28 <0.001 9.63 4.10, 22.61
Residence   <0.001     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.44 1.20, 1.73   1.49 1.31, 1.69   1.37 1.28, 1.47
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.92 1.42, 2.60 <0.001 1.64 1.33, 2.04 <0.001 1.62 1.45, 1.81
 Postmenopausal status 6178 (32.5) 0.062 1.41 0.98, 2.03 0.002 1.49 1.16, 1.92 <0.001 1.68 1.46, 1.93
Body mass index   0.778     0.378     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.350 0.81 0.52, 1.26 0.147 0.80 0.59, 1.08 0.461 1.05 0.92, 1.20
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.860 0.98 0.82, 1.18 0.492 1.05 0.92, 1.19 <0.001 1.29 1.21, 1.38
 Obese (≥28 g/m2) 2002 (10.5) 0.731 1.10 0.75, 1.50 0.747 1.04 0.81, 1.34 <0.001 1.80 1.52, 2.13
Mode of delivery   0.391     0.196     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.340 1.13 0.88, 1.44 0.097 1.16 0.97, 1.37 <0.001 1.45 1.32, 1.58
 Forceps or vacuum delivery 746 (3.9) 0.136 1.34 0.91, 1.96 0.058 1.31 0.99, 1.72 0.002 1.29 1.10, 1.53
 Cesarean section                    
  1 2399 (12.6) 0.522 0.90 0.65, 1.24 0.824 0.98 0.79, 1.21 0.047 0.90 0.82, 1.00
  ≥2 55 (3.0) 0.575 0.56 0.08, 4.19 0.847 1.11 0.39, 3.16 0.387 0.78 0.45, 1.37
 Nulliparity 2251 (11.9) 0.241 1.27 0.85, 1.91 0.118 1.25 0.95, 1.64 0.031 0.87 0.77, 0.99
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   2.60 2.16, 3.11   2.00 1.74, 2.30   1.87 1.69, 2.06
Hormone replacement therapy   0.021     0.008     0.040    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.53 0.30, 0.91   0.58 0.38, 0.87   0.73 0.55, 0.99
Pelvic organ prolapse   0.004     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.17 1.29, 3.65   2.65 1.85, 3.80   2.37 1.67, 3.37
Hypertension   0.278     0.004     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.13 0.91, 1.42   1.27 1.08, 1.49   1.41 1.24, 1.61
Diabetes   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.81 1.33, 2.45   1.63 1.29, 2.08   1.60 1.25, 2.06
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.97 1.47, 2.63   1.46 1.20, 1.78   1.32 1.18, 1.48
Alcohol consumption   0.036     0.006     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.36 1.02, 1.82   1.31 1.08, 1.59   1.24 1.12, 1.38

* The sample was small, so the 95% CI could not be calculated.

OR c = odds ratio; CI = confidence interval; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence; LUTS = lower urinary tract symptoms.

gr5

Fig. 5 Receiver operating characteristic curve analysis for the relationship between number of deliveries and moderately or severely bothersome lower urinary tract symptoms (LUTS). (A) Moderately to severely bothersome LUTS in relation to number of deliveries. Area = 0.653; 95% confidence interval 0.639–0.667. When n = 2(1.5), the sensitivity is 63.1% and the specificity is 61.3%. (B) Any severely bothersome LUTS in relation to the number of deliveries. Area = 0.689; 95% confidence interval 0.666–0.711. When n = 2(1.5), the sensitivity is 70.0% and the specificity is 60.1%.

We conducted a PubMed search for English-language articles focused on epidemiology and bother of LUTS ( Table 7 ). The prevalence of any LUTS in our study was higher (55.5%) than in the large population-based EPIC study with an original five-nation European and North American survey (48.1%) [7] but lower than in an Internet-based study in the USA, the UK, and Sweden (76.3%) [5] and population-based studies in Brazil (84.1%) [6] , Russia, the Czech Republic, and Turkey (81–87%) [17] . The prevalence of any LUTS was lower than that in Korea (68.9%) [18] . In China, prevalence varies between studies. Hong Kong and Taiwan showed higher prevalence (74%) [19] , but a previous study in Fuzhou, China, identified an even lower rate (39.7%) [14] .

Table 7 Overview of published English-language population-based studies on the epidemiology and bother of lower urinary tract symptoms *

Study Countries/

Year conducted
Total no.

(women, n, %)
Response rate (%) Age (yr) Definition;

questionnaire
Numbers of LUTS

evaluated
Prevalence of any or individual LUTS in women (%) Moderate to severe bother (women %) Race Methods
Irwin et al 2006 [7] Canada; Germany;

Italy; Sweden; UK

2005
19 165

(N/A)
33 ≥18 2002 ICS;

Self-designed
18 Any: 66.6% a or 48.1% b ;

Nocturia: 54.5% a or 24.0% b ;

Storage: 59.2% a ; Voiding: 19.5%;

Urgency:12.8%; UI: 13.1%; SUI:6.4%;

Terminal dribble: 9.9%
N/A Predominantly white Computer-assisted telephone
Coyne et al 2009 [5] USA;

UK;

Sweden;

2007–2008
30 000

(15 861, 52.9%)

USA 20 000;

UK 7500;

Sweden 2500
59.6;

60.6;

52.3
40–99 2002 ICS;

self-designed;

questions according to ICS

definition
20 c Any: 76.3% (sometimes) or 52.5% (often);

Nocturia: 75.8% a or 33.7% b ;

Terminal dribble: 38.3%; Urgency: 35.7%;

Frequency: 24.6%;

SUI: 31.8%; UUI: 24.4%
Somewhat bothered:

Urgency: 74.7%;

SUI: 74%;

Dysuria: 73.5%

UUI: 71.3%
White; Black; Hispanic; Asian/other Internet-based
Koga et al 2014 [17] Russia;

Czech Republic;

Turkey;

2010
3130

(1614, 51.6%)
N/A ≥18 ICS;

European EPIC questionnaire
18 Any: 81%; 83%; 87% a ;

Storage: 74%, 73%, 81%;

Voiding: 41%, 32, 38%;

Postmicturition: 20%, 26%, 21%;

UI: 20%
Frequency: 58%;

Nocturia: 54%
N/A Computer-assisted telephone and face-to-face
Moreira et al 2013 [6] Brazil;

2006–2007
3000

(1500, 50.0%)
83 ≥30 2002 ICS;

Self-designed
18 c Any: 84.1% a

Storage: 76.4%; Voiding: 33.7%;

Postmicturition: 12.8%;

Nocturia: 71.2% a and 36.5% b ;

Frequency: 23.7%; Urgency: 10.0%;

UI: 5.8%; Terminal dribble: 13.0%
Any bother:

Urgency: 75%,

Nocturia: ≤50%
White; Black;

Mixed; Other
Interviewer-

administered
Coyne et al 2013 [21] USA;

2010
10 000

(5023, 50.2%)
56.7 18–70 ICS;

self-designed;

questions according to ICS

definition
11 c Any: N/A

Terminal dribble: 33.4%;

Nocturia: 27.8% b , c

Urgency: 24.4% c ; UUI: 18.5% c ;

Incomplete emptying: 20.9%**
N/A African-Americans; Hispanics; Whites Internet-based
Boyle et al 2003 [4] Netherlands;

France; UK; Korea;

N/A
8769

(3790, 43.2%)
N/A 40–79 I-PSS ≥ 8 7 c 18.0%; 12.6%; 23.7%; 19.9% 8 ≤ I-PSS ≤ 20: 11.0–19.5%;

20 ≤ I-PSS ≤ 35: 1.6–4.2%
N/A Self-completed

postal and direct
Kupelian et al 2006 [2] USA;

2002–2005
5506

(3205, 58.2%)
N/A 30–79 AUA-SI ≥ 8;

SF-12
N/A 18.6% N/A Blacks; Hispanics; Whites; (no differences) In-person and self-administered
Nørby et al 2005 [37] Denmark;

N/A
5379

(427, 7.9%)
47.7 d ≥50 I-PSS≥8 7 20% N/A N/A Mailed
Agarwal et al 2014 [29] Finland;

2003–2004
3727

(1888, 53.7%)
62.4 18–79 ICS;

DAN-PSS
12 N/A Population:

Urgency: 7.9%;

SUI: 6.5%;

Nocturia: 6.0%
N/A Mailed
Zumrutba et al 2014 [20] Turkey;

2012
1555

(919, 57.1%)
74 ≥18 2002 ICS;

Self-designed;

ICIQ-SF(UI)
18 Any:71.0% a ;

Storage: 64.1%; Voiding: 37.8%;

Urgency: 35.6%; Any UI:38.7%;

Nocturia: 31.0% a or 18.6% b ;

MUI: 9.0%; SUI: 21.2%; UUI: 3.3%;

SUI: 25.5%
N/A N/A Self-administered,

trained physicians and nurses helped
Herschorn et al 2008 [36] Canada;

2002
1,000

(518, 51.8%)
N/A ≥18 ICS;

Self designed
6 Any: 56.8% a or 40.9% b ;

Nocturia: 39.4% a or 10.2% b ;

UI: 28.8%; UUI:9.3%;

Frequency: 14.9%; Urgency: 14.1%
N/A N/A Telephone survey
Homma et al 2006 [8] Japan;

N/A
4570

(2380, 53.1%)
45 ≥40 Self-designed and validated 8 Frequency: 50.0%; Nocturia:69.0% a ;

Other LUTS: 2–27% (≥1 times/wk);

Other LUTS: 2–20% (≥1 times/d)
Nocturia;

SUI
N/A Self-administered
Lee et al 2011 [18] Korea;

2006
2000

(1112, 55.6%)
22.1 ≥18 ICS;

European EPIC questionnaire;

I-PSS
N/A Any: 68.9%;

Storage: 64.4% a and 47.4% b ;

Voiding:25.9%; Postmicturition 13.9%;

Nocturia:48.2% a and 14.0% b ;

UI: 28.4%; SUI:20.7%; MUI: 4.1%
(8 ≤ I-PSS ≤ 18)

5.8%;

(19 ≤ I-PSS ≤ 35)

0.8%
N/A Telephone survey
Zhang et al 2005 [14] China (Fuzhou);

2004
4684 women 77.2 ≥20 ICS;

BFLUTS
12 Any: 39.7% a

Storage: 37.3%; Voiding: 13.4%;

SUI: 16.6%;UUI: 10.0%; Urgency: 10.2%;

Frequency: 16.4%; Nocturia: 9.9%;

Hesitancy: 6.8%; Intermittence: 4.8%;

Straining: 4.5%
N/A Han Mailed
Our study China (nationwide)

2006
18 992 women 94.96 ≥20 ICS;

ICIQ-FLUTS
10 Any: 55.5% b

Storage: 53.9% b ; Voiding: 12.9%;

SUI: 18.9%;UUI: 2.6%; Urgency: 23.3%;

Frequency: 17.3%; Nocturia: 23.4% b ;

Hesitancy: 5.6%; Intermittence: 7.1%;

Straining: 3.3%; Pain/burning:4.5%
Urgency:29.93%;

UUI: 27.6%
Predominantly

Han
Interviewer-

administered

* This table does not include every published study; only the major or largest studies from each country from 2002 to November 2014 are presented here.

a Nocturia defined as ≥1 times/night.

b Nocturia defined as ≥2 times/night.

c This information was not reported in the paper but was deduced or calculated by us.

d The women's response rate, not the total response rate.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; SUI = stress urinary incontinence; UUI = urgency urinary incontinence; N/A = this information was not reported in the paper; BFLUTS = Bristol Female Lower Urinary Tract Symptoms; DAN-PSS = Danish Prostatic Symptom Score; ICS = International Continence Society; I-PSS = International Prostate Symptom Score; LUTS = lower urinary tract symptoms; AUA-SI = American Urological Association Symptom Index; SF-12 = Medical Outcomes Study 12-item Short Form Survey; ICIQ-FLUTS = International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms.

Individual prevalence comparisons may be more appropriate than overall prevalence comparisons among studies. LUTS in our study more commonly involved urinary storage problems rather than voiding difficulties, which were also reported for Western studies [6], [7], [14], [17], [18], and [20]. In the EPIC study, the ICS definition of nocturia (two or more voids per night) yielded similar prevalence (24.0%) to ours [7] . However, the prevalence rates for SUI, UUI, or UI reported by the participants in our study were much lower than those in the Western studies (4.5–44%) [5], [17], [18], [21], and [22]. There seem to be ethnic differences. Asian women were less prone to UI or LUTS, which is in line with a global prevalence analysis by Milsom et al [23] and an incidence study by Townsend et al [24] . Some of the differences observed can probably be attributed to methodological differences among studies. However, several racially and ethnically diverse studies also yielded ethnic differences in LUTS prevalence [5], [6], and [21]. These differences may result from many sociocultural and environmental factors, in addition to genetic factors that can affect bladder health, and require further study to distinguish.

4.1. Symptom-specific bother of individual LUTS

Assessment of the bother of symptoms is of key clinical relevance because it relates to both quality-of-life impairment and treatment-seeking [25] . Clinical practice guidelines suggest that only patients reporting bothersome symptoms should be targeted for intervention and that watchful waiting is appropriate for those with minimal symptoms [26] . There is a need to assess the frequency of individual LUTS and their respective bother ratings.

All of the individual LUTS caused bother, and storage symptoms were more likely to cause moderate or severe bother than voiding symptoms, especially urgency or UUI. We found that symptoms and bother did not correspond in a straightforward manner. Nocturia was most frequently rated as bothersome; however, it was primarily rated as no bother or as a minor bother. Urgency and UUI were less frequently rated as bothersome and usually ranked as severe or moderate. This information could assist in targeting patients who need intervention. Our study revealed similar findings to those of Moreira et al [6] , who also noted that urgency was usually associated with moderate or severe bother, whereas nocturia was usually associated with minor bother. Our study is partly in line with those of Coyne et al [27] and Møller et al [28] , who reported that the symptoms most frequently rated bothersome were nocturia, SUI, and urgency [27] and [28], and is similar to a national Finnish study that showed a high burden of urgency and UUI [29] . Because urgency seems to have a more negative impact on patient quality of life, it should be a leading consideration for medical intervention.

4.2. Potential risk factors for LUTS

The pathogenesis of LUTS is not completely understood, but it is considered a multifactorial process. A broader view of LUTS has shown that potential risk factors include age, race, micturition habits, lifestyle factors, and pathologic conditions [30] . We performed a detailed evaluation of potential risk factors for any, individual, and bothersome LUTS, and found that all were influenced by multiple factors. Older age and coexisting POP were both strong predictors for every type of LUTS. Regardless of the number of pregnancies, women who had only cesarean deliveries had no increase in odds for LUTS of any type. Women with multiple vaginal deliveries had increased odds for storage and bothersome LUTS compared with those who had spontaneous vaginal single births, in agreement with prospective studies focusing on reproductive history and progression of LUTS [31] and [32]. Prolonged labor may have a strong influence on any severely bothersome LUTS. Voiding symptoms were less likely to be associated with multiple vaginal deliveries or higher BMI. Multiple vaginal deliveries and prolonged labor may cause repeated injury to the muscles, nerves, and connective tissue of the pelvic floor, and have a negative impact on bladder control. The close relationship between LUTS and POP has rarely been explored. Having either incontinence or prolapse may be associated with an increased risk of developing the other condition [33] . It is possible that women with advanced POP experience more obstructive urinary symptoms, as reported by Rosenzweig et al [34] and Raz et al [35] . Family studies and twin studies have demonstrated that LUTS and POP are both heritable [33] . Our study, however, is cross-sectional, and the risk factors we identified cannot be considered established causes of LUTS. Some of the results should be interpreted with caution.

The strengths of our study are the large representative population-based sample of women and the high response rate. These enabled us to accurately determine the prevalence and bother associated with LUTS. The use of a professional questionnaire for urinary symptoms based strictly on criteria in the 2002 ICS guidelines also enabled us to compare our results with those for other studies.

Our study has some limitations. This analysis was the second of a study conducted 8 yr ago; the prevalence of LUTS may be higher today than at that time. Missing data were not handled well in our study. In addition, our questionnaire did not assess all LUTS, and the cross-sectional design is poor way to ascertain risk factors. Longitudinal studies are needed to better understand the temporal nature and associations with persistence of LUTS.

This was the largest population-based epidemiological study to date of LUTS in adult women. In the 55.5% of adult Chinese women who experienced LUTS, the most prevalent symptoms were nocturia, urgency, and SUI. Urgency and UUI were most frequently reported as moderately or severely bothersome. The likelihood of any, individual, and bothersome LUTS may involve multiple factors, with older age and coexisting POP as strong predictors.

Author contributions: Lan Zhu had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Zhu, Lang.

Acquisition of data: Zhu, Li, Gong, Q. Liu, X. Liu, Zhang.

Analysis and interpretation of data: Zhang, Xu, Zhu.

Drafting of the manuscript: Zhang.

Critical revision of the manuscript for important intellectual content: Zhu, Lang.

Statistical analysis: Zhang, Xu.

Obtaining funding: Zhu, Lang.

Administrative, technical, or material support: None.

Supervision: None.

Other (specify): None.

Financial disclosures: Lan Zhu certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: None.

Funding/Support and role of the sponsor: This study received financial support from the Chinese government under 5-year national project number 3053750. The only role of the sponsor was in approval of the manuscript.

Acknowledgments: We are grateful to the Bristol Urological Institute (Bristol, UK) for authorization of their Female Lower Urinary Tract Symptoms (BFLUTS) questionnaires. We would like to thank Shaomei Han for her professional guidance in data analysis.

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Lower urinary tract symptoms (LUTS) have attracted substantial attention in recent years partly because to their high prevalence but primarily because of heightened awareness of their detrimental impact on health-related quality of life [1] . Studies report that one in five adult women complain about moderate to severe LUTS, and one in ten adults have newly developed LUTS, often along with resulting substantial bother and interference with daily activities [2] and [3]. By 2018, an estimated 2.3 billion people will be affected by at least one LUTS. The prevalence of LUTS is likely to be greater in women than in men. The regional burden of these conditions is estimated to be greatest in Asia [1] . Many large-scale epidemiologic studies of LUTS have been conducted in Western countries, and prevalence estimates reported for LUTS subsets vary widely from 13% to 76% [4] and [5]. This variation could be due to differences in study populations, symptom assessment, data collection, or definitions used [3], [6], and [7]. In China, there have been relatively few epidemiologic studies of LUTS. Several studies have estimated the prevalence of LUTS in Asian countries such as Japan, Korea, and Taiwan [8], [9], and [10]; however, there are notable inconsistencies in the prevalence rates reported across studies, and few were conducted nationwide. In addition, many were limited by bias related to sex, specific LUTS, and age groups.

The aim of this study was to provide estimates of the prevalence and potential risk factors of LUTS and the bother they impose in a nationwide population-based sample of adult women in China.

2.1. Study design and participants

This analysis is the second of a previous study. The data were from a national cross-sectional survey on urinary incontinence (UI) in 20 000 adult women aged ≥20 yr in China. The previous survey included two phases: a pilot study conducted in Beijing, China [11] , and a subsequent nationwide study [12] and [13]. Detailed study procedures and results for stress urinary incontinence (SUI), urgency urinary incontinence (UUI), and mixed urinary incontinence (MUI) have been described in previous reports [11], [12], and [13].

Phase 1 (a pilot survey in Beijing) assessed a representative sample of approximately 5221 respondents (from one urban district and one rural district) who were interviewed face to face by trained interviewers using a standardized questionnaire. The eligibility criteria stipulated women aged ≥20 yr in the general population who had lived in the registered areas for at least 10 yr. We excluded women who were medically diagnosed with cognitive impairment and who could not understand the questions. Detailed study procedures and results were published [11] .

Phase 2 was a nationwide survey conducted between February and July 2006 in six regions of China. The sampling process was multistage and stratified according to geographic region (northwest, southwest, north, east, northeast, and central-south China) and degree of urbanization (large cities and undeveloped economic status were assessed on the basis of the gross domestic product for each province). Eligibility and exclusion criteria were in accord with the pilot survey (on the basis of Chinese population data from 2006). The rationale for the recruitment approach, the study design, and the interpretation of results has been described previously [12] and [13]. Ethics committee approval and written informed consent were obtained.

Our previous study focused on UI, so we recalculated the sample size for this reanalysis according to a previous study conducted in Fuzhou, China, which reported 39.7% prevalence of LUTS in female residents [14] . We aimed to survey at least six age deciles: 20–29, 30–39, 40–49, 50–59, 60–69, and ≥70 yr. A minimal sample size was calculated for detection of 39.7% prevalence of LUTS, with a 5% estimated error and a 95% confidence interval (CI). Considering a 20% refusal rate, a total of 16 805 participants would be required for the LUTS reanalysis according to the formula

FORMULA:

stripin: si1.gif

The sample size was large enough for our reanalysis.

2.2. Diagnostic criteria

The definitions in this study are consistent with the standards recommended by the 2002 International Continence Society (ICS) guidelines [15] . Nocturia is a condition whereby a person awakens at night one or more times to void, and was defined as two or more micturitions per night in our study. Daytime frequency is a condition whereby a patient voids too often by day. In our study, frequency was defined as voiding eight times or more per day. Respondents who reported both UUI and SUI symptoms were classified as having MUI. Those who reported UI without symptoms of UUI or SUI were categorized as having other UI. Women who had given birth to multiple children were defined as having more than one delivery.

2.3. Measurements

We used a modified Bristol Female Lower Urinary Tract Symptoms questionnaire [16] that consisted of two parts. Part 1 included general information about age, marital status, occupation, menopausal status, medically diagnosed disease status, parity, mode of delivery for childbirth, and offspring birth weights. Part 2 was a Chinese version of the International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms (ICIQ-FLUTS). The Chinese version of the questionnaire was translated by survey research experts. To assess the accuracy of the translation, the Chinese version was translated back to English and compared by an independent agent. A pilot study of 40 women was performed before the survey took place to ensure the validity of the questionnaire. The readability of the Chinese version of the questionnaire was at the primary school level.

The questionnaire included an assessment of ten types of LUTS: nocturia, daytime frequency, urgency, UUI, SUI, other incontinence, pain or burning, hesitancy, straining, and intermittency. Participants were asked to rate how often individual LUTS were experienced during the previous 4 wk and, if LUTS were experienced, to what degree the symptoms were bothersome. All subjects reporting LUTS were asked to describe the frequency of the symptoms. Nocturia was measured as the number of micturitions per night, and frequency was defined as eight or more times per day. The other symptoms were measured according to how long participants had experienced them in the previous 4 wk, classified as: no (never); <10 d (occasionally); 10–20 d (sometimes); 20 d (most of the time); or every day (all of the time). The prevalence of other LUTS was defined as answers other than no. The bother associated with each symptom was evaluated using a scale ranging from 0 (not bothered at all) to 10 (greatly bothered). Bother was also defined by dividing the Likert responses into three groups: minor (rated 1–4), moderate (rated 5–7), and severe (rated 8–10). Detailed information on sociodemographic background, reproductive factors, defecation, and medical conditions was also collected. The interviewers underwent standardized training and regular quality control checks.

2.4. Statistical analysis

The data were finally stratified into eight age deciles. We performed χ2 tests to compare prevalence differences between groups. Receiver operating characteristic (ROC) curve distribution was used to assess the number of deliveries and their relationship to LUTS with moderate or severe bother. A multivariate model was set up to assess bother and individual LUTS-related potential risk factors and to estimate odds ratios and 95% CIs; this model was adapted for all factors in the final version. A two-sided p value ≤0.05 was considered for statistical significance. EpiData software ( http://www.epidata.dk/ ) was used for data entry and error detection. SPSS v.12.0 (IBM Corp., Armonk, NY, USA) was used for statistical analysis.

As shown in Figure 1 , 976 (4.88%) of the questionnaires could not be evaluated and were excluded in the previous UI study; 32 participants were further excluded because of missing information regarding reproductive factors or LUTS symptoms. A total of 18 992 participants (94.96%) were entered into our data analyses. The age distribution ranged from 20 to 99 yr, with a mean of 44.9 yr (±15.9 yr) (the age distribution in our study was similar to the total adult population in the 2006 National Census). Overall, 438 participants (2.3%) were from minority groups. The numbers of participants from urban and rural areas were equal (50% vs 50%). Table 1 lists the sociodemographic characteristics of the participants.

gr1

Fig. 1 Study flowchart. UI = urinary incontinence; LUTS = lower urinary tract symptoms.

Table 1 Characteristics of the 18 992 subjects interviewed

Characteristic Data
Mean age, yr (SD) 44.91 (15.9)
Age, n (%)
 20–29 yr 3381 (17.8)
 30–39 yr 4778 (25.2)
 40–49 yr 4199 (22.1)
 50–59 yr 2881 (15.2)
 60–69 yr 2029 (10.7)
 70–79 yr 1194 (6.3)
 80–89 yr 442 (2.3)
 ≥90 yr 88 (0.5)
Residence, n (%)
 Urban 9490 (50.0)
 Rural 9502 (50.0)
Current marital status, n (%)
 Single, never married 1392 (7.3)
 Married 15 976 (84.1)
 Remarried 178 (0.9)
 Divorced/separated 77 (0.4)
 Widowed 1369 (7.2)
Mean body mass index, kg/m2 (SD) 23.4 (3.8)
Body mass index, n (%)
 Underweight (<18.5 kg/m2) 1140 (6.0)
 Normal (18.5–23.9 kg/m2) 10 370 (54.6)
 Overweight (24–27.9 kg/m2) 5480 (28.9)
 Obese (≥28 kg/m2) 2002 (10.5)
Median parity, pregnancies (range) 1 (0–10)
Parity, n (%)
 Nulliparous 2251 (11.9)
 Primiparous (=1) 8980 (47.3)
 Multiparous (=2) 4286 (22.6)
 Multiparous (≥3) 3475 (18.3)
Job, n (%)
 Manual labor 4343 (22.9)
 Intellectual labor 14 649 (77.1)
Race, n (%)
 Han 18 554 (97.7)
 Minority 438 (2.3)

3.1. Prevalence of LUTS

The frequencies of individual LUTS are shown in Table 2 . The prevalence of any LUTS was 55.5% and increased with age. Storage symptoms were more common than voiding symptoms (53.9% vs 12.9%). Nocturia was the most common symptom (23.4%), followed by urgency (23.3%) and SUI (18.9%); incontinence was also highly prevalent (31.9%). Straining was the least common symptom (3.3%; Table 2 ).

Table 2 Prevalence of individual lower urinary tract symptoms by age and residence

  Symptoms, n (%)
  Total Age group Residence
  (n = 18 992) 20–29 yr 30–39 yr 40–49 yr 50–59 yr 60–69 yr 70–79 yr 80–90 yr ≥90 yr p value b Urban Rural p value b
    (n = 3381) (n = 4778) (n = 4199) (n = 2881) (n = 2029) (n = 1194) (n = 442) (n = 88)   (n = 9490) (n = 9502)  
Nocturia
 ≥2 times/night 4450 (23.4) 302 (8.9) 542 (11.3) 745 (17.7) 900 (31.2) 891 (43.9) 715 (59.9) 289 (65.4) 66 (75.0) <0.001 2161 (22.8) 2289 (24.1) 0.032
Frequency 3290 (17.3) 438 (13.0) 654 (13.7) 666 (15.9) 583 (20.2) 454 (22.4) 329 (27.6) 133 (30.1) 33 (37.5) <0.001 1934 (20.4) 1356 (14.3) <0.001
Urgency 4430 (23.3) 399 (11.8) 774 (16.2) 966 (23.0) 847 (29.4) 655 (32.3) 503 (42.1) 237 (53.6) 49 (55.7) <0.001 2361 (24.9) 2069 (21.8) <0.001
UI
 Any UI 6052 (31.9) 362 (10.7) 948 (19.8) 1488 (35.4) 1316 (45.7) 990 (48.8) 643 (53.9) 247 (55.9) 58 (65.9) <0.001 2733 (28.8) 3319 (34.9) <0.001
 UUI 488 (2.6) 35 (1.0) 73 (1.5) 84 (2.0) 81 (2.8) 94 (4.6) 97 (8.1) 23 (5.2) 1 (1.1) <0.001 272 (2.9) 216 (2.3) 0.01
 SUI 3,592 (18.9) 178 (5.3) 659 (13.8) 993 (23.6) 812 (28.2) 556 (27.4) 286 (24.0) 85 (19.2) 23 (26.1) <0.001 1555 (16.4) 2037 (21.4) <0.001
 MUI 1,788 (9.4) 43 (1.3) 206 (4.3) 398 (9.5) 405 (14.1) 320 (15.8) 247 (20.7) 136 (30.8) 33 (37.5) <0.001 752 (7.9) 1036 (10.9) <0.001
Other UI 858 (4.5) 123 (3.6) 71 (1.5) 138 (3.3) 174 (6.0) 145 (7.1) 134 (11.2) 52 (11.8) 21 (23.9) <0.001 468 (4.9) 390 (4.1) 0.006
 Any involuntary a 536 (2.8) 13 (0.4) 50 (1.0) 95 (2.3) 110 (3.8) 100 (4.9) 102 (8.5) 45 (10.2) 21 (23.9) <0.001 235 (2.5) 301 (3.2) 0.004
 Nocturnal enuresis 172 (0.9) 10 (0.3) 12 (0.3) 27 (0.6) 30 (1.0) 25 (1.2) 40 (3.4) 19 (4.3) 9 (10.2) <0.001 105 (1.1) 67 (0.7) 0.004
 During intercourse a 336 (2.0) 110 (3.7) 30 (0.6) 53 (1.3) 72 (2.8) 42 (3.0) 27 (4.2) 2 (1.1) 0 <0.001 227 (2.7) 109 (1.3) <0.001
Pain/burning 854 (4.5) 71 (2.1) 175 (3.7) 208 (5.0) 167 (5.8) 130 (6.4) 65 (5.4) 29 (6.6) 9 (10.2) <0.001 374 (3.9) 480 (5.1) <0.001
Hesitancy 1072 (5.6) 137 (4.1) 171 (3.6) 167 (4.0) 200 (6.9) 155 (7.6) 152 (12.7) 71 (16.1) 19 (21.6) <0.001 675 (7.1) 397 (4.2) <0.001
Straining 626 (3.3) 39 (1.2) 87 (1.8) 117 (2.8) 110 (3.8) 110 (5.4) 101 (8.5) 44 (10.0) 18 (20.5) <0.001 378 (4.0) 248 (2.6) <0.001
Intermittency 1346 (7.1) 110 (3.3) 211 (4.4) 231 (5.5) 259 (9.0) 233 (11.5) 197 (16.5) 83 (18.8) 22 (25.0) <0.001 801 (8.4) 545 (5.7) <0.001
Storage symptoms 10 245 (53.9) 1117 (33.0) 1930 (40.4) 2299 (54.8) 1956 (67.9) 1500 (73.9) 987 (82.7) 375 (84.8) 81 (92.0) <0.001 5249 (55.3) 4996 (52.6) <0.001
Voiding symptoms 2444 (12.9) 249 (7.4) 452 (9.5) 475 (11.3) 461 (16.0) 393 (19.4) 271 (22.7) 113 (25.6) 30 (34.1) <0.001 1353 (14.3) 1091 (11.5) <0.001
Any LUTS 10 540 (55.5) 1185 (35.0) 2034 (42.6) 2360 (56.2) 1988 (69.0) 1521 (75.0) 992 (83.1) 378 (85.5) 82 (93.2) <0.001 5420 (57.1) 5120 (53.9) <0.001

a 16 695 women were sexually active and included in the category UI during sexual intercourse. The category Any involuntary represents women who reported leaking for no reason or any involuntary loss of urine.

b The Pearson χ2 test was used to compare differences in the prevalence of individual LUTS by age and residence.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence.

A notable age-related trend was observed for the prevalence of any LUTS, storage, or voiding symptoms, with approximately 50% greater prevalence observed for the oldest compared to the youngest participants ( Table 2 ; Fig 2 and Fig 3). UI was frequent in women aged ≤70 yr, but nocturia was more prevalent in those aged ≥70 yr. Urgency was usually reported by women aged ≤50 yr. Frequency, urgency, hesitancy, straining, and intermittency were more common in urban women (p < 0.001). Rural women experienced more nocturia (22.8% vs 24.1%; p = 0.032). UI was the most common symptom (28.8% vs 34.9%; p < 0.001) in both areas, but particularly in rural areas ( Fig. 3 ).

gr2

Fig. 2 Age-specific prevalence of lower urinary tract symptom subtypes. UI = urinary incontinence.

gr3

Fig. 3 Urban and rural prevalence differences for individual lower urinary tract symptoms. UI = urinary incontinence.

3.2. Symptom-specific bother of LUTS

The extent to which study participants were bothered by each urinary symptom is summarized in Table 3 and Fig. 4 . We found that no bother or minor bother were the most common responses reported for every symptom. Only 14.6–29.9% of participants with bothersome LUTS reported a moderate to severe impact on their quality of life; 4.2–11.5% reported severe bother. Some of the most prevalent symptoms were among those least commonly reported as bothersome, such as SUI (67.4%). Some of the most likely to be rated as bothersome were not necessarily the most likely to cause moderate or severe bother, such as nocturia (19.5%). Urgency was among the least likely to cause bother but was the symptom most likely to cause severe (11.5%) or moderate to severe bother (29.9%), followed by UUI (10.8% and 27.6%, respectively). Frequency was the storage symptom that was least commonly reported as causing moderate or severe bother (14.6%).

Table 3 Self-reported bother related to individual lower urinary tract symptoms

Bother Symptoms, n (%)
  Nocturia Frequency Urgency UUI a SUI Pain/burning Hesitancy Straining Intermittency
Likert score
 0 14 854 (78.21) 17 090 (89.99) 16 242 (85.52) 17 245 (90.80) 15 366 (80.91) 18 270 (96.20) 18 333 (96.53) 18 527 (97.55) 18 136 (95.49)
 1 1505 (7.92) 818 (4.31) 771 (4.06) 534 (2.81) 1302 (6.86) 285 (1.50) 271 (1.43) 156 (0.82) 284 (1.50)
 2 879 (4.63) 426 (2.24) 553 (2.91) 329 (1.73) 868 (4.57) 173 (0.91) 140 (0.74) 114 (0.60) 200 (1.05)
 3 625 (3.29) 271 (1.43) 403 (2.12) 277 (1.46) 540 (2.84) 97 (0.51) 100 (0.53) 64 (0.34) 136 (0.72)
 4 322 (1.70) 110 (0.58) 200 (1.05) 126 (0.66) 269 (1.42) 56 (0.29) 46 (0.24) 32 (0.17) 75 (0.39)
 5 284 (1.50) 94 (0.49) 256 (1.35) 149 (0.78) 247 (1.30) 47 (0.25) 34 (0.18) 34 (0.18) 58 (0.31)
 6 141 (0.74) 67 (0.35) 149 (0.78) 97 (0.51) 108 (0.57) 16 (0.08) 24 (0.13) 24 (0.13) 35 (0.18)
 7 133 (0.70) 36 (0.19) 103 (0.54) 46 (0.24) 80 (0.42) 11 (0.06) 12 (0.06) 7 (0.04) 17 (0.09)
 8 137 (0.72) 41 (0.22) 147 (0.77) 86 (0.45) 85 (0.45) 20 (0.11) 12 (0.06) 16 (0.08) 25 (0.13)
 9 112 (0.59) 39 (0.21) 168 (0.88) 103 (0.54) 127 (0.67) 17 (0.09) 20 (0.11) 18 (0.09) 26 (0.14)
 10 0 0 0 0 0 0 0 0 0
Any bother b 4138 1902 2750 1747 3626 722 659 465 856
Moderate to severe bother 807 (19.50) 277 (14.56) 823 (29.93) 483 (27.60) 647 (17.84) 111 (15.37) 102 (15.48) 99 (21.29) 161 (18.81)
Any severe bother 249 (6.02) 80 (4.21) 315 (11.45) 189 (10.80) 212 (5.85) 37 (5.12) 32 (4.86) 34 (7.31) 51 (5.96)
Any LUTS 4450 3290 4430 2276 5380 854 1072 626 1346
Bother rate (%) 92.99 57.81 62.08 76.78 67.40 84.54 61.47 74.28 63.60

a SUI and UUI include participants with mixed urinary incontinence.

b Any bother: participants reported that they were bothered by at least one individual LUTS.

UUI = urgency urinary incontinence; SUI = stress urinary incontinence; LUTS = lower urinary tract symptoms.

gr4

Fig. 4 Symptom-specific bother and extent of individual lower urinary tract symptoms. Bother was also defined by dividing the Likert responses into three groups: (a) 1–4, minor; (b) 5–7, moderate; and (c) 8–10, severe. UUI = urgency urinary incontinence; SUI = stress urinary incontinence.

Voiding symptoms were less likely to cause moderate or severe bother than storage symptoms (p < 0.001). Pain or burning was the second most frequent bother (84.5%), but straining and intermittency were more likely to cause moderate or severe bother (21.3% and 18.8%, respectively; Table 3 ).

3.3. Potential risk factors for LUTS

Risk factors for LUTS according to logistic regression analysis are shown in Table 4, Table 5, and Table 6. We identified multiple risk factors for any, individual, and bothersome LUTS; older age, postmenopausal status, constipation, and coexisting pelvic organ prolapse (POP) increased the odds for every type of LUTS. Older age and coexisting POP were both strong predictors (p ≤ 0.05). In comparison with spontaneous vaginal single births, our study showed a higher risk of storage and moderate or severe bothersome LUTS in women with multiple vaginal deliveries (1.46-fold and 1.26-fold, respectively) and instrumental deliveries (1.25-fold and 1.22-fold, respectively). ROC distributions showed that multiple deliveries were more closely related to any severely bothersome LUTS ( Fig. 5 ). Women who had single or multiple deliveries via cesarean section had no increase in odds for every LUTS (p > 0.05), as did women who had spontaneous vaginal single births. Participants with histories of prolonged labor and perineal laceration had increased odds for moderate or severe bothersome LUTS; prolonged labor may have a stronger influence (1.99-fold, with adjustment for all other factors). Voiding symptoms were less influenced by delivery histories. Lifestyle factors and pathologic conditions such as higher body mass index (BMI), hypertension, diabetes, alcohol consumption, and smoking had various effects on any, individual, and bothersome LUTS (Table 4, Table 5, and Table 6).

Table 4 Multivariate analyses of associations between patient characteristics and bothersome lower urinary tract symptoms

  n (%) Any LUTS bother (n = 6950) Moderate to severe LUTS bother (n = 1695) Any severe LUTS bother (n = 652)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted OR a 95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) <0.001 1.43 1.26, 1.63 0.078 1.29 0.97, 1.71 0.072 1.63 0.96, 2.79
 40–49 yr 4199 (22.1) <0.001 1.85 1.62, 2.12 <0.001 2.04 1.54, 2.69 <0.001 2.91 1.73, 4.90
 50–59 yr 2881 (15.2) <0.001 2.08 1.75, 2.47 <0.001 2.71 1.96, 3.74 <0.001 4.99 2.83, 8.80
 60–69 yr 2029 (10.7) <0.001 2.12 1.73, 2.60 <0.001 2.29 1.60, 3.28 <0.001 4.45 2.41, 8.20
 70–79 yr 1194 (6.3) <0.001 2.75 2.21, 3.43 <0.001 2.70 1.86, 3.91 <0.001 5.16 2.77, 9.64
 80–89 442 (2.3) <0.001 3.59 2.74, 4.71 <0.001 3.58 2.39, 5.37 <0.001 6.59 3.40, 12.78
  ≥90 yr 88 (0.5) <0.001 9.24 5.19, 16.47 <0.001 7.30 4.18, 12.77 <0.001 16.56 7.59, 36.10
Residence   <0.001     0.109     0.846    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.16 1.08, 1.24   1.10 0.98, 1.23   1.02 0.86, 1.21
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.66 1.49, 1.86 <0.001 1.79 1.48, 2.15 <0.001 2.26 1.68, 3.02
 Postmenopausal status 6178 (32.5) <0.001 1.55 1.35, 1.77 <0.001 1.55 1.25, 1.92 0.016 1.51 1.08, 2.12
Body mass index   <0.001     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.425 1.06 0.91, 1.24 0.008 1.41 1.09, 1.81 0.844 0.96 0.60, 1.51
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.16 1.08, 1.25 <0.001 1.29 1.15, 1.46 0.001 1.38 1.14, 1.66
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.47 1.27, 1.71 <0.001 1.70 1.37, 2.10 <0.001 1.81 1.33, 2.48
Mode of delivery   <0.001     0.001     0.006    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.25 1.14, 1.36 0.002 1.26 1.09, 1.46 0.001 1.51 1.20, 1.92
 Forceps or vacuum delivery 746 (3.9) 0.026 1.20 1.02, 1.42 0.134 1.22 0.94, 1.58 0.240 1.29 0.85, 1.96
 Cesarean section                    
  1 2,399 (12.6) 0.001 0.83 0.75, 0.93 0.095 0.83 0.67, 1.03 0.502 0.87 0.59, 1.30
  ≥2 55 (3.0) 0.965 1.01 0.58, 1.77 0.401 1.42 0.63, 3.23 0.356 1.76 0.53, 5.83
 Nulliparity 2251 (11.9) <0.001 0.64 0.55, 0.74 0.050 0.74 0.54, 1.00 0.090 1.50 0.94, 2.41
Prolonged labor b   <0.001     <0.001     <0.001    
 No (ref.) 13 444 (95.7)   1.00     1.00     1.00  
 Yes 599 (4.3)   1.62 1.35, 1.94   1.99 1.58, 2.50   2.19 1.58, 3.02
Perineal laceration b   <0.001     0.018     0.700    
 No (ref.) 10 312 (77.0)   1.00 -   1.00     1.00  
 Yes 3088 (23.0)   1.22 1.12, 1.33   1.17 1.03, 1.34   1.04 0.85, 1.04
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.97 1.79, 2.16   2.22 1.95, 2.52   2.28 1.89, 2.76
Hormone replacement therapy   0.009     0.510     0.879    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.69 0.52, 0.91   1.17 0.74, 1.84   0.95 0.50, 1.82
Pelvic organ prolapse   <0.001     <0.001     0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.08 1.55, 2.77   2.29 1.65, 3.18   2.12 1.35, 3.35
Hypertension   <0.001     <0.001     0.017    
 Nonexistent (ref.) 17 093 (90.0)   1.00 -   1.00     1.00  
 Present 1899 (10.0)   1.48 1.33, 1.65   1.49 1.29, 1.72   1.29 1.05, 1.60
Diabetes   0.001     0.001     0.011    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.38 1.14, 1.67   1.48 1.18, 1.86   1.52 1.10, 2.10
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.25 1.11, 1.39   1.54 1.28, 1.85   2.10 1.56, 2.78
Alcohol consumption   <0.001     0.466     0.168    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.37 1.23, 1.52   1.07 0.90, 1.27   1.20 0.93, 1.56

a The adjusted odds ratios with 95% confidence intervals are presented. All of the factors, except for prolonged labor and perineal laceration, were adjusted in the multivariate model. For prolonged labor and perineal laceration, the other factors were adjusted. Pelvic organ prolapse, hypertension, and diabetes were defined according to hospital diagnosis.

b There were some missing data for prolonged labor (244) and perineal laceration (887) because the participants could not accurately recall these histories.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 5 Multivariate analyses of associations between patient characteristics and the presence of storage, voiding, and incontinence lower urinary tract symptoms

  n (%) Storage symptoms (n = 10 245) Voiding symptoms (n = 2444) Any urinary incontinence (n = 6052)
    p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI p value Adjusted

OR a
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.001 1.21 1.09, 1.36 0.001 1.38 1.14, 1.67 <0.001 1.55 1.34, 1.80
 40–49 yr 4199 (22.1) <0.001 1.75 1.56, 1.98 0.001 1.42 1.16, 1.74 <0.001 2.66 2.29, 3.10
 50–59 yr 2881 (15.2) <0.001 2.00 1.70, 2.36 <0.001 1.57 1.22, 2.01 <0.001 2.80 2.32, 3.38
 60–69 yr 2029 (10.7) <0.001 2.01 1.64, 2.47 0.001 1.63 1.22, 2.18 <0.001 2.46 1.98, 3.06
 70–79 yr 1194 (6.3) <0.001 3.30 2.61, 4.17 <0.001 1.84 1.36, 2.48 <0.001 3.02 2.39, 3.81
 80–89 442 (2.3) <0.001 3.93 2.86, 5.39 <0.001 2.03 1.44, 2.86 <0.001 3.32 2.52, 4.37
 ≥90 yr 88 (0.5) <0.001 9.14 4.11, 20.29 <0.001 2.98 1.75, 5.05 <0.001 5.87 3.58, 9.65
Residence   <0.001     <0.001     0.006    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.35 1.26, 1.45   1.32 1.19, 1.45   0.90 0.84, 0.97
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.55 1.39, 1.73 <0.001 1.75 1.50, 2.05 <0.001 1.61 1.43, 1.81
 Postmenopausal status 6178 (32.5) <0.001 1.63 1.42, 1.87 <0.001 1.50 1.24, 1.82 <0.001 1.44 1.26, 1.65
Body mass index   <0.001     0.204     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.445 1.05 0.92, 1.21 0.138 0.85 0.68, 1.06 0.137 0.88 0.74, 1.04
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.31 1.23, 1.41 0.839 0.99 0.90, 1.09 <0.001 1.34 1.25, 1.45
 Obese (≥28 g/m2) 2002 (10.5) <0.001 1.87 1.59, 2.21 0.180 1.14 0.94, 1.39 <0.001 1.77 1.52, 2.06
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) <0.001 1.46 1.34, 1.60 <0.001 1.31 1.15, 1.49 <0.001 1.63 1.49, 1.79
 Forceps or vacuum delivery 746 (3.9) 0.007 1.25 1.06, 1.48 0.002 1.41 1.14, 1.75 <0.001 1.35 1.14, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.044 0.90 0.82, 1.00 0.590 0.96 0.81, 1.12 <0.001 0.72 0.63, 0.81
  ≥2 55 (3.0) 0.234 0.71 0.41, 1.25 0.513 1.30 0.60, 2.83 0.247 0.69 0.37, 1.29
 Nulliparity 2251 (11.9) 0.042 0.88 0.77, 1.00 0.293 1.12 0.91, 1.37 <0.001 0.71 0.59, 0.84
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.77 1.60, 1.95   2.18 1.95, 2.43   1.87 1.70, 2.06
Hormone replacement therapy   0.050     0.001     0.211    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.75 0.56, 1.00   0.58 0.41, 0.81   0.83 0.63, 1.11
Pelvic organ prolapse   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.38 1.68, 3.36   2.35 1.72, 3.21   1.96 1.47, 2.60
Hypertension   <0.001     0.202     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.41 1.24, 1.61   1.09 0.95, 1.25   1.29 1.16, 1.44
Diabetes   0.001     <0.001     0.114    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.49 1.17, 1.89   1.61 1.31, 1.99   1.17 0.96, 1.41
Smoking   <0.001     <0.001     0.306    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.31 1.17, 1.46   1.70 1.46, 1.98   1.06 0.95, 1.20
Alcohol consumption   <0.001     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.22 1.10, 1.35   1.37 1.18, 1.59   1.51 1.35, 1.68

a All of the factors were adjusted.

CI = confidence interval; LUTS = lower urinary tract symptoms; OR = odds ratio; ref. = reference.

Table 6 Multivariate analyses of the association between patient characteristics and individual LUTS and any LUTS with adjustment for all factors

  n (%) Nocturia (n = 4450) Frequency (n = 3290) Urgency (n = 4430)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.598 0.96 0.81, 1.13 0.013 1.22 1.04, 1.42 <0.001 1.56 1.33, 1.82
 40–49 yr 4199 (22.1) 0.002 1.30 1.10, 1.54 <0.001 1.44 1.22, 1.70 <0.001 2.07 1.76, 2.43
 50–59 yr 2881 (15.2) <0.001 1.84 1.50, 2.26 <0.001 1.58 1.27, 1.95 <0.001 2.20 1.80, 2.69
 60–69 yr 2029 (10.7) <0.001 2.63 2.08, 3.32 <0.001 1.72 1.34, 2.21 <0.001 2.05 1.62, 2.60
 70–79 yr 1194 (6.3) <0.001 5.13 4.00, 6.57 <0.001 2.26 1.74, 2.94 <0.001 3.03 2.37, 3.88
 80–89 442 (2.3) <0.001 7.08 5.29, 9.48 <0.001 2.59 1.91, 3.52 <0.001 4.66 3.49, 6.21
 ≥90 yr 88 (0.5) <0.001 12.95 7.60, 22.06 <0.001 3.47 2.13, 5.67 <0.001 5.19 3.19, 8.45
Residence   0.692     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   0.98 0.91, 1.07   1.45 1.33, 1.58   1.29 1.19, 1.39
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.43 1.25, 1.64 <0.001 1.42 1.24, 1.63 <0.001 1.41 1.24, 1.61
 Postmenopausal status 6178 (32.5) <0.001 1.57 1.35, 1.83 <0.001 1.52 1.28, 1.81 <0.001 1.35 1.16, 1.57
Body mass index   <0.001     0.055     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.133 1.15 0.96, 1.39 0.611 1.05 0.88, 1.24 0.844 1.02 0.85, 1.12
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) <0.001 1.46 1.35, 1.59 0.392 1.04 0.95, 1.13 <0.001 1.24 1.14, 1.34
 Obese (≥28 g/m2) 2002 (10.5) <0.001 2.16 1.84, 2.54 0.006 1.28 1.07, 1.53 <0.001 1.56 1.33, 1.83
Mode of delivery   <0.001     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.037 1.12 1.01, 1.24 0.002 0.83 0.74, 0.93 0.000 1.41 1.27, 1.57
 Forceps or vacuum delivery 746 (3.9) 0.685 1.04 0.86, 1.26 0.372 1.09 0.90, 1.33 0.002 1.34 1.11, 1.60
 Cesarean section                    
  1 2399 (12.6) 0.707 0.97 0.85, 1.12 0.212 1.09 0.95, 1.24 0.132 1.10 0.97, 1.25
  ≥2 55 (3.0) 0.600 1.18 0.63, 2.20 0.247 0.62 0.28, 1.39 0.567 0.81 0.40, 1.66
 Nulliparity 2251 (11.9) <0.001 0.59 0.49, 0.72 0.004 1.28 1.08, 1.51 0.020 1.22 1.03, 1.44
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.52 1.37, 1.69   1.26 1.13, 1.40   1.84 1.66, 2.02
Hormone replacement therapy   0.039     0.388     0.009    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.73 0.54, 0.98   1.17 0.82, 1.66   0.67 0.50, 0.91
Pelvic organ prolapse   0.002     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   1.62 1.20, 2.17   1.78 1.32, 2.41   2.00 1.51, 2.67
Hypertension   <0.001     0.075     0.112    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.48 1.32, 1.65   1.12 0.99, 1.27   1.10 0.98, 1.23
Diabetes   <0.001     0.084     0.049    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.73 1.42, 2.10   1.20 0.98, 1.48   1.21 1.00, 1.47
Smoking   0.047     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.15 1.00, 1.33   0.59 0.52, 0.68   2.20 1.94, 2.49
Alcohol consumption   0.004     0.133     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   0.82 0.72, 0.94   1.10 0.97, 1.24   1.29 1.14, 1.45
  n (%) UUI (n = 488) SUI (n = 3592) MUI (n = 1788)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.017 1.77 1.11, 2.83 <0.001 1.78 1.47, 2.15 <0.001 2.28 1.59, 3.26
 40–49 yr 4199 (22.1) 0.003 2.08 1.28, 3.38 <0.001 2.74 2.26, 3.31 <0.001 4.09 2.88, 5.82
 50–59 yr 2881 (15.2) 0.022 1.99 1.10, 3.58 <0.001 2.62 2.09, 3.29 <0.001 4.94 3.36, 7.26
 60–69 yr 2029 (10.7) 0.001 2.83 1.49, 5.38 <0.001 2.21 1.71, 2.86 <0.001 4.57 3.01, 6.93
 70–79 yr 1194 (6.3) 0.000 5.03 2.64, 9.57 <0.001 1.87 1.42, 2.46 <0.001 6.40 4.18, 9.79
 80–89 442 (2.3) 0.003 3.00 1.45, 6.24 0.040 1.43 1.02, 2.00 <0.001 11.15 7.13, 17.44
 ≥90 yr 88 (0.5) 0.624 0.60 0.08 4.68 0.001 2.41 1.41, 4.14 <0.001 17.01 9.34, 30.95
Residence   0.022     0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.26 1.03, 1.53   0.87 0.80, 0.95   0.81 0.72, 0.90
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.89 1.34, 2.67 <0.001 1.37 1.20, 1.57 <0.001 1.69 1.40, 2.03
 Postmenopausal status 6178 (32.5) 0.004 1.86 1.22, 2.84 <0.001 1.33 1.15, 1.55 0.077 1.21 0.98, 1.49
Body mass index   0.454     <0.001     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.706 1.09 0.70, 1.69 0.39 0.91 0.73, 1.13 0.001 0.56 0.40, 0.79
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.214 1.14 0.93, 1.40 <0.001 1.35 1.24, 1.47 0.058 1.12 1.00, 1.26
 Obese (≥28 g/m2) 2002 (10.5) 0.157 1.31 0.90, 1.91 <0.001 1.42 1.20, 1.68 <0.001 1.60 1.31, 1.96
Mode of delivery   0.182     <0.001     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.176 1.21 0.92, 1.60 <0.001 1.25 1.12, 1.38 <0.001 1.85 1.60, 2.15
 Forceps or vacuum delivery 746 (3.9) 0.801 0.94 0.56, 1.57 0.007 1.28 1.07, 1.54 0.014 1.39 1.07, 1.81
 Cesarean section                    
  1 2,399 (12.6) 0.045 1.42 1.01, 2.01 <0.001 0.66 0.57, 0.77 0.257 0.88 0.70, 1.10
  ≥2 55 (3.0) 0.997 * * 0.544 0.81 0.40, 1.62 0.843 0.90 0.32, 2.55
 Nulliparity 2251 (11.9) 0.040 1.61 1.02, 2.54 <0.001 0.34 0.26, 0.44 0.004 0.56 0.38, 0.83
Constipation   0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.49 1.18, 1.88   1.28 1.15, 1.42   2.15 1.89, 2.45
Hormone replacement therapy   0.075     0.883     0.143    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.57 0.30, 1.06   1.03 0.74, 1.42   0.74 0.50, 1.11
Pelvic organ prolapse   0.001     0.050     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.40 1.41, 4.06   1.36 1.01, 1.86   2.31 1.66, 3.21
Hypertension   0.390     0.004     0.067    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.12 0.87, 1.44   1.19 1.06, 1.34   1.14 0.99, 1.32
Diabetes   0.564     0.030     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.12 0.76, 1.67   0.79 0.64, 0.98   1.54 1.23, 1.93
Smoking   0.755     0.084     0.927    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.05 0.76, 1.47   1.13 0.98, 1.29   1.01 0.84, 1.21
Alcohol consumption   0.906     <0.001     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.02 0.75, 1.02   1.34 1.18, 1.52   1.54 1.30, 1.83
  n (%) Other UI (n = 858) Pain/burning (n = 854) Hesitancy (n = 1072)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     0.016     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.007 0.63 0.45, 0.88 0.010 1.52 1.11, 2.09 0.912 1.02 0.78, 1.33
 40–49 yr 4199 (22.1) 0.108 1.31 0.94, 1.81 0.001 1.75 1.26, 2.43 0.898 0.98 0.74, 1.31
 50–59 yr 2881 (15.2) 0.003 1.82 1.22, 2.72 0.015 1.65 1.10, 2.45 0.136 1.31 0.92, 1.87
 60–69 yr 2029 (10.7) 0.008 1.84 1.17, 2.89 0.062 1.55 0.98, 2.45 0.334 1.23 0.81, 1.86
 70–79 yr 1194 (6.3) <0.001 2.85 1.81, 4.51 0.503 1.19 0.72, 1.95 0.002 1.95 1.28, 2.98
 80–89 442 (2.3) <0.001 2.88 1.74, 4.76 0.317 1.34 0.76, 2.37 <0.001 2.43 1.53, 3.85
 ≥90 yr 88 (0.5) <0.001 6.18 3.26, 11.72 0.089 2.04 0.90, 4.64 <0.001 3.25 1.70, 6.21
Residence   0.143     0.021     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.12 0.96, 1.30   0.83 0.71, 0.97   1.64 1.42, 1.89
Menstrual condition   0.007     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) 0.010 1.43 1.09, 1.89 <0.001 1.90 1.51, 2.39 <0.001 1.72 1.36, 2.18
 Postmenopausal status 6178 (32.5) 0.010 1.51 1.11, 2.06 0.042 1.35 1.01, 1.81 0.002 1.57 1.18, 2.08
Body mass index   0.298     0.643     0.537    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.300 1.18 0.87, 1.60 0.555 0.89 0.62, 1.30 0.187 0.81 0.59, 1.11
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.079 1.16 0.98, 1.36 0.218 0.91 0.78, 1.06 0.701 0.97 0.84, 1.12
 Obese (≥28 g/m2) 2002 (10.5) 0.312 1.17 0.86, 1.59 0.796 0.96 0.70, 1.31 0.669 1.06 0.81, 1.40
Mode of delivery   <0.001     <0.001     0.086    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.213 1.15 0.93, 1.42 <0.001 1.59 1.30, 1.94 0.785 1.03 0.85, 1.25
 Forceps or vacuum delivery 746 (3.9) 0.657 1.09 0.75, 1.60 0.030 1.47 1.04, 2.07 0.024 1.40 1.05, 1.88
 Cesarean section                    
  1 2399 (12.6) 0.654 0.93 0.68, 1.27 0.104 1.23 0.96, 1.57 0.373 0.90 0.71, 1.14
  ≥2 55 (3.0) 0.681 1.28 0.39, 4.20 0.230 1.90 0.67, 5.40 0.555 0.65 0.15, 2.75
 Nulliparity 2251 (11.9) <0.001 2.40 1.77, 3.26 0.184 0.77 0.53, 1.13 0.170 1.21 0.92, 1.60
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   1.87 1.57, 2.22   2.18 1.84, 2.57   2.11 1.82, 2.45
Hormone replacement therapy   0.859     0.497     0.071    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   1.06 0.57, 1.97   1.27 0.64, 2.50   0.65 0.40, 1.04
Pelvic organ prolapse   <0.001     0.026     0.012    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.65 1.76, 4.00   1.74 1.07, 2.84   1.81 1.14, 2.88
Hypertension   0.206     0.284     0.022    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.14 0.93, 1.39   0.89 0.71, 1.11   1.24 1.03, 1.48
Diabetes   0.017     0.041     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.44 1.07, 1.93   1.41 1.01, 1.95   1.61 1.24, 2.10
Smoking   0.267     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.16 0.90, 1.50   2.16 1.68, 2.78   1.70 1.70, 2.65
Alcohol consumption   0.846     0.119     0.013    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.03 0.80, 1.31   1.22 0.95, 1.56   1.33 1.06, 1.66
  n (%) Straining (n = 626) Intermittency (n = 1346) Any LUTS (n = 10 540)
    p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI p value Adjusted

OR
95% CI
Age group   <0.001     <0.001     <0.001    
 20–29 yr (ref.) 3381 (17.8)   1.00     1.00     1.00  
 30–39 yr 4778 (25.2) 0.006 1.84 1.19, 2.84 0.003 1.51 1.15, 1.99 <0.001 1.22 1.09, 1.36
 40–49 yr 4199 (22.1) <0.001 2.45 1.57, 3.81 0.001 1.65 1.24, 2.20 <0.001 1.71 1.51, 1.92
 50–59 yr 2881 (15.2) <0.001 2.64 1.57, 4.43 <0.001 2.08 1.48, 2.92 <0.001 1.91 1.62, 2.25
 60–69 yr 2029 (10.7) <0.001 3.29 1.85, 5.85 <0.001 2.27 1.54, 3.34 <0.001 1.92 1.56, 2.35
 70–79 yr 1194 (6.3) <0.001 4.72 2.63, 8.47 <0.001 3.22 2.17, 4.78 <0.001 3.05 2.41, 3.86
 80–89 442 (2.3) <0.001 5.31 2.84, 9.93 <0.001 3.66 2.37, 5.63 <0.001 3.71 2.69, 5.12
 ≥90 yr 88 (0.5) <0.001 11.61 5.45, 24.73 <0.001 5.05 2.75, 9.28 <0.001 9.63 4.10, 22.61
Residence   <0.001     <0.001     <0.001    
 Rural (ref.) 9502 (50.0)   1.00     1.00     1.00  
 Urban 9490 (50.0)   1.44 1.20, 1.73   1.49 1.31, 1.69   1.37 1.28, 1.47
Menstrual condition   <0.001     <0.001     <0.001    
 Normal menstruation (ref.) 11 106 (58.5)   1.00     1.00     1.00  
 Perimenopausal status 1708 (9.0) <0.001 1.92 1.42, 2.60 <0.001 1.64 1.33, 2.04 <0.001 1.62 1.45, 1.81
 Postmenopausal status 6178 (32.5) 0.062 1.41 0.98, 2.03 0.002 1.49 1.16, 1.92 <0.001 1.68 1.46, 1.93
Body mass index   0.778     0.378     <0.001    
 Underweight (<18.5 g/m2) 1140 (6.0) 0.350 0.81 0.52, 1.26 0.147 0.80 0.59, 1.08 0.461 1.05 0.92, 1.20
 Normal (18.5–23.9 g/m2) (ref.) 10 370 (54.6)   1.00     1.00     1.00  
 Overweight (24–27.9 g/m2) 5480 (28.9) 0.860 0.98 0.82, 1.18 0.492 1.05 0.92, 1.19 <0.001 1.29 1.21, 1.38
 Obese (≥28 g/m2) 2002 (10.5) 0.731 1.10 0.75, 1.50 0.747 1.04 0.81, 1.34 <0.001 1.80 1.52, 2.13
Mode of delivery   0.391     0.196     <0.001    
 Spontaneous vaginal delivery                    
  1 (ref.) 6341 (33.4)   1.00     1.00     1.00  
  ≥2 7200 (37.9) 0.340 1.13 0.88, 1.44 0.097 1.16 0.97, 1.37 <0.001 1.45 1.32, 1.58
 Forceps or vacuum delivery 746 (3.9) 0.136 1.34 0.91, 1.96 0.058 1.31 0.99, 1.72 0.002 1.29 1.10, 1.53
 Cesarean section                    
  1 2399 (12.6) 0.522 0.90 0.65, 1.24 0.824 0.98 0.79, 1.21 0.047 0.90 0.82, 1.00
  ≥2 55 (3.0) 0.575 0.56 0.08, 4.19 0.847 1.11 0.39, 3.16 0.387 0.78 0.45, 1.37
 Nulliparity 2251 (11.9) 0.241 1.27 0.85, 1.91 0.118 1.25 0.95, 1.64 0.031 0.87 0.77, 0.99
Constipation   <0.001     <0.001     <0.001    
 No (ref.) 16 570 (87.2)   1.00     1.00     1.00  
 Yes 2422 (12.8)   2.60 2.16, 3.11   2.00 1.74, 2.30   1.87 1.69, 2.06
Hormone replacement therapy   0.021     0.008     0.040    
 No (ref.) 18 765 (98.8)   1.00     1.00     1.00  
 Yes 227 (1.2)   0.53 0.30, 0.91   0.58 0.38, 0.87   0.73 0.55, 0.99
Pelvic organ prolapse   0.004     <0.001     <0.001    
 Nonexistent (ref.) 18 775 (98.8)   1.00     1.00     1.00  
 Present 217 (1.1)   2.17 1.29, 3.65   2.65 1.85, 3.80   2.37 1.67, 3.37
Hypertension   0.278     0.004     <0.001    
 Nonexistent (ref.) 17 093 (90.0)   1.00     1.00     1.00  
 Present 1899 (10.0)   1.13 0.91, 1.42   1.27 1.08, 1.49   1.41 1.24, 1.61
Diabetes   <0.001     <0.001     <0.001    
 Nonexistent (ref.) 18 476 (97.3)   1.00     1.00     1.00  
 Present 516 (2.7)   1.81 1.33, 2.45   1.63 1.29, 2.08   1.60 1.25, 2.06
Smoking   <0.001     <0.001     <0.001    
 No (ref.) 13 559 (71.4)   1.00     1.00     1.00  
 Yes 5433 (28.6)   1.97 1.47, 2.63   1.46 1.20, 1.78   1.32 1.18, 1.48
Alcohol consumption   0.036     0.006     <0.001    
 No (ref.) 11 822 (62.2)   1.00     1.00     1.00  
 Yes 7170 (37.8)   1.36 1.02, 1.82   1.31 1.08, 1.59   1.24 1.12, 1.38

* The sample was small, so the 95% CI could not be calculated.

OR c = odds ratio; CI = confidence interval; UI = urinary incontinence; UUI = urgency urinary incontinence; SUI = stress urinary incontinence; MUI = mixed urinary incontinence; LUTS = lower urinary tract symptoms.

gr5

Fig. 5 Receiver operating characteristic curve analysis for the relationship between number of deliveries and moderately or severely bothersome lower urinary tract symptoms (LUTS). (A) Moderately to severely bothersome LUTS in relation to number of deliveries. Area = 0.653; 95% confidence interval 0.639–0.667. When n = 2(1.5), the sensitivity is 63.1% and the specificity is 61.3%. (B) Any severely bothersome LUTS in relation to the number of deliveries. Area = 0.689; 95% confidence interval 0.666–0.711. When n = 2(1.5), the sensitivity is 70.0% and the specificity is 60.1%.

We conducted a PubMed search for English-language articles focused on epidemiology and bother of LUTS ( Table 7 ). The prevalence of any LUTS in our study was higher (55.5%) than in the large population-based EPIC study with an original five-nation European and North American survey (48.1%) [7] but lower than in an Internet-based study in the USA, the UK, and Sweden (76.3%) [5] and population-based studies in Brazil (84.1%) [6] , Russia, the Czech Republic, and Turkey (81–87%) [17] . The prevalence of any LUTS was lower than that in Korea (68.9%) [18] . In China, prevalence varies between studies. Hong Kong and Taiwan showed higher prevalence (74%) [19] , but a previous study in Fuzhou, China, identified an even lower rate (39.7%) [14] .

Table 7 Overview of published English-language population-based studies on the epidemiology and bother of lower urinary tract symptoms *

Study Countries/

Year conducted
Total no.

(women, n, %)
Response rate (%) Age (yr) Definition;

questionnaire
Numbers of LUTS

evaluated
Prevalence of any or individual LUTS in women (%) Moderate to severe bother (women %) Race Methods
Irwin et al 2006 [7] Canada; Germany;

Italy; Sweden; UK

2005
19 165

(N/A)
33 ≥18 2002 ICS;

Self-designed
18 Any: 66.6% a or 48.1% b ;

Nocturia: 54.5% a or 24.0% b ;

Storage: 59.2% a ; Voiding: 19.5%;

Urgency:12.8%; UI: 13.1%; SUI:6.4%;

Terminal dribble: 9.9%
N/A Predominantly white Computer-assisted telephone
Coyne et al 2009 [5] USA;

UK;

Sweden;

2007–2008
30 000

(15 861, 52.9%)

USA 20 000;

UK 7500;

Sweden 2500
59.6;

60.6;

52.3
40–99 2002 ICS;

self-designed;

questions according to ICS

definition
20 c Any: 76.3% (sometimes) or 52.5% (often);

Nocturia: 75.8% a or 33.7% b ;

Terminal dribble: 38.3%; Urgency: 35.7%;

Frequency: 24.6%;

SUI: 31.8%; UUI: 24.4%
Somewhat bothered:

Urgency: 74.7%;

SUI: 74%;

Dysuria: 73.5%

UUI: 71.3%
White; Black; Hispanic; Asian/other Internet-based
Koga et al 2014 [17] Russia;

Czech Republic;

Turkey;

2010
3130

(1614, 51.6%)
N/A ≥18 ICS;

European EPIC questionnaire
18 Any: 81%; 83%; 87% a ;

Storage: 74%, 73%, 81%;

Voiding: 41%, 32, 38%;

Postmicturition: 20%, 26%, 21%;

UI: 20%
Frequency: 58%;

Nocturia: 54%
N/A Computer-assisted telephone and face-to-face
Moreira et al 2013 [6] Brazil;

2006–2007
3000

(1500, 50.0%)
83 ≥30 2002 ICS;

Self-designed
18 c Any: 84.1% a

Storage: 76.4%; Voiding: 33.7%;

Postmicturition: 12.8%;

Nocturia: 71.2% a and 36.5% b ;

Frequency: 23.7%; Urgency: 10.0%;

UI: 5.8%; Terminal dribble: 13.0%
Any bother:

Urgency: 75%,

Nocturia: ≤50%
White; Black;

Mixed; Other
Interviewer-

administered
Coyne et al 2013 [21] USA;

2010
10 000

(5023, 50.2%)
56.7 18–70 ICS;

self-designed;

questions according to ICS

definition
11 c Any: N/A

Terminal dribble: 33.4%;

Nocturia: 27.8% b , c

Urgency: 24.4% c ; UUI: 18.5% c ;

Incomplete emptying: 20.9%**
N/A African-Americans; Hispanics; Whites Internet-based
Boyle et al 2003 [4] Netherlands;

France; UK; Korea;

N/A
8769

(3790, 43.2%)
N/A 40–79 I-PSS ≥ 8 7 c 18.0%; 12.6%; 23.7%; 19.9% 8 ≤ I-PSS ≤ 20: 11.0–19.5%;

20 ≤ I-PSS ≤ 35: 1.6–4.2%
N/A Self-completed

postal and direct
Kupelian et al 2006 [2] USA;

2002–2005
5506

(3205, 58.2%)
N/A 30–79 AUA-SI ≥ 8;

SF-12
N/A 18.6% N/A Blacks; Hispanics; Whites; (no differences) In-person and self-administered
Nørby et al 2005 [37] Denmark;

N/A
5379

(427, 7.9%)
47.7 d ≥50 I-PSS≥8 7 20% N/A N/A Mailed
Agarwal et al 2014 [29] Finland;

2003–2004
3727

(1888, 53.7%)
62.4 18–79 ICS;

DAN-PSS
12 N/A Population:

Urgency: 7.9%;

SUI: 6.5%;

Nocturia: 6.0%
N/A Mailed
Zumrutba et al 2014 [20] Turkey;

2012
1555

(919, 57.1%)
74 ≥18 2002 ICS;

Self-designed;

ICIQ-SF(UI)
18 Any:71.0% a ;

Storage: 64.1%; Voiding: 37.8%;

Urgency: 35.6%; Any UI:38.7%;

Nocturia: 31.0% a or 18.6% b ;

MUI: 9.0%; SUI: 21.2%; UUI: 3.3%;

SUI: 25.5%
N/A N/A Self-administered,

trained physicians and nurses helped
Herschorn et al 2008 [36] Canada;

2002
1,000

(518, 51.8%)
N/A ≥18 ICS;

Self designed
6 Any: 56.8% a or 40.9% b ;

Nocturia: 39.4% a or 10.2% b ;

UI: 28.8%; UUI:9.3%;

Frequency: 14.9%; Urgency: 14.1%
N/A N/A Telephone survey
Homma et al 2006 [8] Japan;

N/A
4570

(2380, 53.1%)
45 ≥40 Self-designed and validated 8 Frequency: 50.0%; Nocturia:69.0% a ;

Other LUTS: 2–27% (≥1 times/wk);

Other LUTS: 2–20% (≥1 times/d)
Nocturia;

SUI
N/A Self-administered
Lee et al 2011 [18] Korea;

2006
2000

(1112, 55.6%)
22.1 ≥18 ICS;

European EPIC questionnaire;

I-PSS
N/A Any: 68.9%;

Storage: 64.4% a and 47.4% b ;

Voiding:25.9%; Postmicturition 13.9%;

Nocturia:48.2% a and 14.0% b ;

UI: 28.4%; SUI:20.7%; MUI: 4.1%
(8 ≤ I-PSS ≤ 18)

5.8%;

(19 ≤ I-PSS ≤ 35)

0.8%
N/A Telephone survey
Zhang et al 2005 [14] China (Fuzhou);

2004
4684 women 77.2 ≥20 ICS;

BFLUTS
12 Any: 39.7% a

Storage: 37.3%; Voiding: 13.4%;

SUI: 16.6%;UUI: 10.0%; Urgency: 10.2%;

Frequency: 16.4%; Nocturia: 9.9%;

Hesitancy: 6.8%; Intermittence: 4.8%;

Straining: 4.5%
N/A Han Mailed
Our study China (nationwide)

2006
18 992 women 94.96 ≥20 ICS;

ICIQ-FLUTS
10 Any: 55.5% b

Storage: 53.9% b ; Voiding: 12.9%;

SUI: 18.9%;UUI: 2.6%; Urgency: 23.3%;

Frequency: 17.3%; Nocturia: 23.4% b ;

Hesitancy: 5.6%; Intermittence: 7.1%;

Straining: 3.3%; Pain/burning:4.5%
Urgency:29.93%;

UUI: 27.6%
Predominantly

Han
Interviewer-

administered

* This table does not include every published study; only the major or largest studies from each country from 2002 to November 2014 are presented here.

a Nocturia defined as ≥1 times/night.

b Nocturia defined as ≥2 times/night.

c This information was not reported in the paper but was deduced or calculated by us.

d The women's response rate, not the total response rate.

LUTS = lower urinary tract symptoms; UI = urinary incontinence; SUI = stress urinary incontinence; UUI = urgency urinary incontinence; N/A = this information was not reported in the paper; BFLUTS = Bristol Female Lower Urinary Tract Symptoms; DAN-PSS = Danish Prostatic Symptom Score; ICS = International Continence Society; I-PSS = International Prostate Symptom Score; LUTS = lower urinary tract symptoms; AUA-SI = American Urological Association Symptom Index; SF-12 = Medical Outcomes Study 12-item Short Form Survey; ICIQ-FLUTS = International Consultation on Incontinence Questionnaire–Female Lower Urinary Tract Symptoms.

Individual prevalence comparisons may be more appropriate than overall prevalence comparisons among studies. LUTS in our study more commonly involved urinary storage problems rather than voiding difficulties, which were also reported for Western studies [6], [7], [14], [17], [18], and [20]. In the EPIC study, the ICS definition of nocturia (two or more voids per night) yielded similar prevalence (24.0%) to ours [7] . However, the prevalence rates for SUI, UUI, or UI reported by the participants in our study were much lower than those in the Western studies (4.5–44%) [5], [17], [18], [21], and [22]. There seem to be ethnic differences. Asian women were less prone to UI or LUTS, which is in line with a global prevalence analysis by Milsom et al [23] and an incidence study by Townsend et al [24] . Some of the differences observed can probably be attributed to methodological differences among studies. However, several racially and ethnically diverse studies also yielded ethnic differences in LUTS prevalence [5], [6], and [21]. These differences may result from many sociocultural and environmental factors, in addition to genetic factors that can affect bladder health, and require further study to distinguish.

4.1. Symptom-specific bother of individual LUTS

Assessment of the bother of symptoms is of key clinical relevance because it relates to both quality-of-life impairment and treatment-seeking [25] . Clinical practice guidelines suggest that only patients reporting bothersome symptoms should be targeted for intervention and that watchful waiting is appropriate for those with minimal symptoms [26] . There is a need to assess the frequency of individual LUTS and their respective bother ratings.

All of the individual LUTS caused bother, and storage symptoms were more likely to cause moderate or severe bother than voiding symptoms, especially urgency or UUI. We found that symptoms and bother did not correspond in a straightforward manner. Nocturia was most frequently rated as bothersome; however, it was primarily rated as no bother or as a minor bother. Urgency and UUI were less frequently rated as bothersome and usually ranked as severe or moderate. This information could assist in targeting patients who need intervention. Our study revealed similar findings to those of Moreira et al [6] , who also noted that urgency was usually associated with moderate or severe bother, whereas nocturia was usually associated with minor bother. Our study is partly in line with those of Coyne et al [27] and Møller et al [28] , who reported that the symptoms most frequently rated bothersome were nocturia, SUI, and urgency [27] and [28], and is similar to a national Finnish study that showed a high burden of urgency and UUI [29] . Because urgency seems to have a more negative impact on patient quality of life, it should be a leading consideration for medical intervention.

4.2. Potential risk factors for LUTS

The pathogenesis of LUTS is not completely understood, but it is considered a multifactorial process. A broader view of LUTS has shown that potential risk factors include age, race, micturition habits, lifestyle factors, and pathologic conditions [30] . We performed a detailed evaluation of potential risk factors for any, individual, and bothersome LUTS, and found that all were influenced by multiple factors. Older age and coexisting POP were both strong predictors for every type of LUTS. Regardless of the number of pregnancies, women who had only cesarean deliveries had no increase in odds for LUTS of any type. Women with multiple vaginal deliveries had increased odds for storage and bothersome LUTS compared with those who had spontaneous vaginal single births, in agreement with prospective studies focusing on reproductive history and progression of LUTS [31] and [32]. Prolonged labor may have a strong influence on any severely bothersome LUTS. Voiding symptoms were less likely to be associated with multiple vaginal deliveries or higher BMI. Multiple vaginal deliveries and prolonged labor may cause repeated injury to the muscles, nerves, and connective tissue of the pelvic floor, and have a negative impact on bladder control. The close relationship between LUTS and POP has rarely been explored. Having either incontinence or prolapse may be associated with an increased risk of developing the other condition [33] . It is possible that women with advanced POP experience more obstructive urinary symptoms, as reported by Rosenzweig et al [34] and Raz et al [35] . Family studies and twin studies have demonstrated that LUTS and POP are both heritable [33] . Our study, however, is cross-sectional, and the risk factors we identified cannot be considered established causes of LUTS. Some of the results should be interpreted with caution.

The strengths of our study are the large representative population-based sample of women and the high response rate. These enabled us to accurately determine the prevalence and bother associated with LUTS. The use of a professional questionnaire for urinary symptoms based strictly on criteria in the 2002 ICS guidelines also enabled us to compare our results with those for other studies.

Our study has some limitations. This analysis was the second of a study conducted 8 yr ago; the prevalence of LUTS may be higher today than at that time. Missing data were not handled well in our study. In addition, our questionnaire did not assess all LUTS, and the cross-sectional design is poor way to ascertain risk factors. Longitudinal studies are needed to better understand the temporal nature and associations with persistence of LUTS.

This was the largest population-based epidemiological study to date of LUTS in adult women. In the 55.5% of adult Chinese women who experienced LUTS, the most prevalent symptoms were nocturia, urgency, and SUI. Urgency and UUI were most frequently reported as moderately or severely bothersome. The likelihood of any, individual, and bothersome LUTS may involve multiple factors, with older age and coexisting POP as strong predictors.

Author contributions: Lan Zhu had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Zhu, Lang.

Acquisition of data: Zhu, Li, Gong, Q. Liu, X. Liu, Zhang.

Analysis and interpretation of data: Zhang, Xu, Zhu.

Drafting of the manuscript: Zhang.

Critical revision of the manuscript for important intellectual content: Zhu, Lang.

Statistical analysis: Zhang, Xu.

Obtaining funding: Zhu, Lang.

Administrative, technical, or material support: None.

Supervision: None.

Other (specify): None.

Financial disclosures: Lan Zhu certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: None.

Funding/Support and role of the sponsor: This study received financial support from the Chinese government under 5-year national project number 3053750. The only role of the sponsor was in approval of the manuscript.

Acknowledgments: We are grateful to the Bristol Urological Institute (Bristol, UK) for authorization of their Female Lower Urinary Tract Symptoms (BFLUTS) questionnaires. We would like to thank Shaomei Han for her professional guidance in data analysis.

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Lower urinary tract symptoms (LUTS) have attracted substantial attention in recent years partly because to their high prevalence but primarily because of heightened awareness of their detrimental impact on health-related quality of life [1] . Studies report that one in five adult women complain about moderate to severe LUTS, and one in ten adults have newly developed LUTS, often along with resulting substantial bother and interference with daily activities [2] and [3]. By 2018, an estimated 2.3 billion people will be affected by at least one LUTS. The prevalence of LUTS is likely to be greater in women than in men. The regional burden of these conditions is estimated to be greatest in Asia [1] . Many large-scale epidemiologic studies of LUTS have been conducted in Western countries, and prevalence estimates reported for LUTS subsets vary widely from 13% to 76% [4] and [5]. This variation could be due to differences in study populations, symptom assessment, data collection, or definitions used [3], [6], and [7]. In China, there have been relatively few epidemiologic studies of LUTS. Several studies have estimated the prevalence of LUTS in Asian countries such as Japan, Korea, and Taiwan [8], [9], and [10]; however, there are notable inconsistencies in the prevalence rates reported across studies, and few were conducted nationwide. In addition, many were limited by bias related to sex, specific LUTS, and age groups.

The aim of this study was to provide estimates of the prevalence and potential risk factors of LUTS and the bother they impose in a nationwide population-based sample of adult women in China.