Study design, materials and methods
Between January 2015 and December 2016, men aged ≥ 50 years, undergoing open radical prostatectomy due to localized intermediate-risk prostate cancer at a large tertiary hospital were prospectively enrolled. Preoperative assessments included validated questionnaires (IPSS and OAB-V8), lower urinary tract ultrasound and urodynamics. LUTS severity was classified as follows: mild (IPSS ≤ 7 points), moderate (IPSS ≥ 8 and ≤ 19 points), and severe (IPSS ≥ 20 points). The OAB-V8 questionnaire (Overactive Bladder-Validated 8-question Screener) was also used to estimate the prevalence of overactive bladder symptoms, which were defined by a score ≥ 8 points.
Preoperative urodynamics were performed 2 weeks before open prostatectomy, in compliance with the ICS Good Urodynamic Practices (1). Bladder outlet obstruction (BOO) was defined by the formula: Detrusor pressure at maximum flow - (2x maximum flow). A value greater than 40 was regarded as BOO, less than 20 as no obstruction, and between 20 and 40 as undetermined. Detrusor underactivity was defined by the bladder contractility index (BCI), calculated by the formula: Detrusor pressure at maximum flow + (5x maximum flow). Values under 100 were regarded as detrusor underactivity.
Postoperative variables included pathological examination findings (Gleason score, presence of extra-prostatic tumor invasion, prostatic apex involvement and perineural invasion) and PSA follow-up. The self-administered questionnaires and medical evaluation of the continence status were undertaken in Jan 2018. Continence status was classified according to two distinct definitions: (a) restrictive (no pad usage and ICIQ-SF = 0) and (b) liberal (<= 1 pad/day).
Data were expressed as mean ± standard deviation. Nominal variables were analyzed using the Fisher exact test. Continuous variables were compared using the Student T test. Statistical analyses were performed using SPSS® version 22.0 for Windows (SPSS Inc., Chicago, IL, USA) and an alpha error inferior to 5% (p<0.05) was considered statistically significant.
Results
Thirty-two participants were prospectively included in the study, with a mean follow-up of 29,48 ± 8.44 months. Mean age was 68.34 ± 5.72 years and mean preoperative IPSS was 10.84 ± 8.05 points (mild = 34.4%, moderate = 53.1%, severe = 12.5%). Mean preoperative OAB-V8 score was 6.62 ± 7.61 points. Preoperative prevalence of OAB (OAB-V8 ≥ 8 points) was 34.4% (n=11).
Mean preoperative PSA was 10.33 ± 9.54. Distribution of Gleason score is shown in figure 1.
Preoperative urodynamics findings are presented in table 1.
In regards to the pathological examination, prostatic apex involvement was found in 4 (12.5%) patients, extra-prostatic tumor invasion in 7 (21.9%), and perineural invasion in 17 (53.1%).
Mean postoperative IPSS score was 4.71 ± 4.31 (p<0.001), mean OAB-V8 score was 3.50 ± 5.35 (p=0.054), and mean ICIQ-SF score was 5.84 ± 6.67. Concerning continence status, 20 (62.5%) patients were regarded as incontinent according to the restrictive definition (occasional use of pad and/or ICIQ-SF >= 1) and 7 (21.9%) according to the liberal one (> 1 pad/day).
There was no statistically significant association between postoperative continence status and pathological examination findings (presence of extra-prostatic tumor invasion, prostatic apex involvement and perineural invasion; p > 0.05). Variables associated with post-prostatectomy urinary incontinence (restrictive definition) were age >= 70 years (p = 0.04) and preoperative DO (p = 0.04).
Interpretation of results
Preoperative baseline LUTS make collecting and interpreting urinary function data after radical prostatectomy challenging. Confusion in the literature is compounded by the discrepancy between patient- and surgeon-reported outcomes. On the other hand, etiology of PPI after RP is usually multifactorial and relates to preoperative lower urinary tract function, operative technique, and altered anatomy (2). Most likely, due to the small number of patients included in this study, it was not possible to demonstrate a statistically significant association between adverse pathological parameters (e.g. extra-prostatic extension, apical invasion, etc) and PPUI.
Our study showed that the prevalence of PPUI varies widely according to the different definitions used in clinical research. Advanced age and preoperative DO were associated with PPUI in the long run (mean follow-up = 29.48 months).