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Is resection weight of transurethral resection of prostate correlated with acute urinary retention rate after surgery? A nationwide database study

Hypothesis / Aims of study
For patients receiving resection weight of transurethral resection of prostate (TURP), acute urinary retention (AUR) after the operation is always a complication of great concern, especially for those without Foley indwelled previously. Some studies indicated the resection weight of TURP may be related to the urodynamic results after TURP. However, whether it is correlated with post-OP AUR rates is still a question. Therefore, this article was designed to analyze the correlation of AUR rates and TURP resection weight after TURP in Taiwan according to the claims of the National Health Insurance (NHI) program.

Study design, materials and methods
From the NHI Research Database of Taiwan, we applied for all the claims of patients who ever visited urology clinic during 2006 to 2010. We received all records of both admission and ambulatory clinics. In Taiwan, the NHI divides TURPs into four categories according to the resection weight (<5g, ≧5~15g, ≧15~50g, and ≧50g, respectively). Those younger than 40 years old or who received TURP < 5g were excluded. AUR was defined as mandatory for any kind of indwelling catheterization. Episodes of AUR after TURP within 2 weeks to 2 months were all examined. As time goes by after TURP, the chance to get AUR became less and less, mainly within 2 weeks. Therefore we focused on the period 2 weeks after TURP. Patients who received transurethral incision of bladder neck or otis or optic urethrotomy within 1 year before TURP or 2 months after TURP were excluded, as well as those who had TURPs within 2 months between each surgery. Patients who had diagnosis of prostate or bladder cancer within 3 months peri-operatively were excluded. ICD-9 codes for diabetes mellitus (DM), cerebral vascular disease (CVA), spinal stenosis (SS), and herniated intervertebral disc (HIVD) were adopted for disease confirmation when the diagnoses existed at least one year before TURP. Descriptive and comparative analyses were performed.

There were 32041 TURPs recorded. The mean age was 72.45. In group A, B ,C, the number of TURPs were 12879 (40.2%), 16345 (51.0%), and 2817 (8.8%), respectively, and the mean age of each group was 72.06, 72.56, and 73.53, with significant difference (P<0.001). Among them, 2543 were associated with AUR (7.94%). The rate of AUR after TURP in each group was 9.05%, 7.49 %, and 5.40%. The difference between all these three groups were significant (P<0.001), with the odds ratio of 1.27 (A to B) and 1.89 (A to C). Age is also a significant predictor of AUR after TURP, with odd ratio of 1.024 (P<0.001). Patient who had previous AUR episodes within 2 months before TURP have higher post-TURP AUR rate (9.46%) than those without AUR before TURP (7.04%), with odds ratio of 1.352 (P<0.001). About co-morbidities, DM and CVA were significant risk factors for AUR after TURP, with odds ratio of 1.107 (P=0.047) and 1.241 (P<0.001) respectively, while SS and HIVD were not significant (P=0.212 and 0.277 respectively).

Interpretation of results
By the NHI database, we may take a glance of AUR after TURP in Taiwan. The mean age was significantly older for the heavier resection weight group of TURP. The most AUR occurred within the group A (TURP ≧5~15g), followed by group B (≧15~50g), and group C (≧50g). This probably indicated that AUR after TURP might be related to the resection weight of prostate. Besides, age, pre-TURP Foley indwelling, DM, and CVA were also significant predictors for post TURP AUR possibility, while SS and HIVD were not.

Concluding message
AUR after TURP might be correlated with the resection weight of prostate. At the same time, age, pre-TURP Foley indwelling, DM, and CVA were also significant factors associated to AUR after TURP , while SS and HIVD were not.

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