Nocturia may be associated with various clinical conditions, however pathophysiologically it may be largely due to NP (defined as nocturnal urine volume ≥33% of total daily urine volume, while 24 hour output remains normal by the International Continence Society). Many patients with overactive bladder (OAB) and benign prostatic hyperplasia (BPH) may have a coexisting NP. Timing of lower urinary tract symptoms (LUTS) may assist in identifying the patients where nocturia is due to NP. However, for patients with mixed causality, further evaluation using a voiding diary may be helpful. In cases where voiding diary is not readily available, we hypothesise that simple questions to patients on their perceived nocturnal void volume and fluid intake may help refine the diagnosis.
Data were drawn from the Adelphi LUTS Disease Specific Programme, a cross sectional survey of physicians (n=635), and their consulting patients in France, Germany, Spain, UK, and the USA. Data regarding diagnosis and prescribed therapy were collected as published previously (Anderson et al. Curr Med Res Opin 2008;24:3063-72). Each physician completed the patient record form for the next 14 consulting patients with diagnosis of BPH, OAB and/or nocturia/NP. Multiple diagnoses, as judged by the treating physician, were also captured. Tests conducted to aid diagnosis were captured, however, tests were neither conducted for this study nor did their absence disqualify the patients to enter the study.
A total of 5335 patients were included in this study. All patients (mean age >60 years) were symptomatic at the time of diagnosis, and reported a varying amount of urgency, daytime and/or nocturnal frequency. Diagnoses of OAB, BPH, or nocturia/NP were mainly based on patient history and, to a lesser extent the voiding diary. NP patients reported that they always (26.6%) or usually (59.5%) passed a significant volume of urine at night. The estimated void volume in NP patients was 38% of the total daily void volume while for other patients it was <33%. NP patients also had a more limited fluid intake before travelling and sleeping (Figure).
Self-reported data on nocturnal void volume and fluid intake are useful in clinical practice to diagnose NP, and differentiate from other LUTS.
