Stress urinary incontinence (SUI) is one of the complications of radical prostatectomy. Although pre-operative urethral function has been associated with the incidence of post-operative SUI [1], it remains unclear as to what affects pre-operative urethral function in males. We investigated the association between clinical factors and pre-operative urethral function in male patients, using the urethral pressure profile test.

We assessed 313 patients who had undergone robot-assisted radical prostatectomy (RARP) between April 2013 and March 2015. Patients receiving neoadjuvant hormonal therapy were excluded. Urethral pressure profiling was performed before, and 3 months after the surgery, in all patients. Baseline patient characteristics were collected from clinical records. Univariate and multivariate analyses were performed to investigate the association between pre- and post-operative maximum urethral closure pressure (MUCP) and the following factors: age, body mass index, American Society of Anesthesiologists (ASA) physical status, history of diabetes mellitus and hypertension, prostate volume, international prostate symptom score, erectile function (EF) domain score of the International Index of Erectile Function (IIEF-15), and current medication, such as calcium channel blockers, α-adrenoceptor blockers, angiotensin receptor blockers, and angiotensin converting enzyme inhibitors.

A total of 187 patients (mean age, 66 ± 6 years) were enrolled. Mean pre-operative MUCP was 83.5 ± 23.2 cmH2O. Univariate analysis revealed that age (≧ 70 years), larger prostate volume (≧ 40 mL), higher IIEF-EF domain (< 13), and the use of calcium channel blockers, were significantly associated with pre-operative MUCP (p = 0.009, 0.003, 0.003, and 0.003, respectively). Following multivariate analysis, these factors were found to be significantly associated with pre-operative MUCP (odds ratio [OR] 0.40, 95% confidence interval [CI] 0.19–0.83, p = 0.01; OR 0.29, 95% CI 0.13–0.62, p = 0.001; OR 0.33, 95% CI 0.16–0.69, p = 0.003; OR 0.34, 95% CI 0.16–0.69, p = 0.003, respectively). Mean post-operative MUCP was 56.0 ± 17.0 cmH2O, with a pre- to post-operative reduction rate of 18%. Univariate analysis revealed that age (≧ 70 years) and pre-operative MUCP (< 80 cmH2O) were significantly associated with post-operative MUCP (p = 0.01 and p < 0.001, respectively). In multivariate analysis, only pre-operative MUCP (<80 cmH2O) was significantly associated with post-operative MUCP (OR 4.28, 95% CI 2.28–8.04, p < 0.001).

The current study indicated that older age, larger prostate volume, worse erectile function, and medication with calcium channel blockers, were significantly associated with worse pre-operative urethral function. Since it is known that chronic ischemia is a contributing factor to the pathogenesis of benign prostate hyperplasia and erectile dysfunction [2], it is possible that impaired urethral function also attributes to the decreased urethral blood supply. Additionally, since calcium channels have been identified in the human urethral rhabdosphincter, calcium channel blocker medication inhibiting channel function might worsen urethral function.

Our study has demonstrated that older age, larger prostate volume, worse erectile function, and calcium channel blockers are significantly associated with low pre-operative MUCP. These factors could represent predictive markers for post-operative SUI.

Dubbelman YD, Groen J, Wildhagen MF, Rikken B, Bosch JL. Urodynamic quantification of decrease in sphincter function after radical prostatectomy: relation to postoperative continence status and the effect of intensive pelvic floor muscle exercises. Neurourol Urodyn 2012; 31(5): 646-51.
Berger AP, Deibl M, Leonhartsberger N, Bektic J, Horninger W, Fritsche G et al. Vascular damage as a risk factor for benign prostatic hyperplasia and erectile dysfunction. BJU Int 2005; 96(7): 1073-8.