Assessing variability of the 24-hour pad weight test in men with post-prostatectomy incontinence

Purpose: Decision-making regarding surgery for post-prostatectomy incontinence (PPI) is challenging. The 24-hour pad weight test is commonly used to objectively quantify PPI. However, pad weight may vary based upon activity level. We aimed to quantify variability in pad weights based upon patient-reported activity. Materials and Methods: 25 patients who underwent radical prostatectomy were prospectively enrolled. All patients demonstrated clinical stress urinary incontinence without clinical urgency urinary incontinence. On three consecutive alternating days, patients submitted 24-hour pad weights along with a short survey documenting activity level and number of pads used. Results: Pad weights collected across the three days were well correlated to the individual (ICC 0.85 (95% CI 0.74-0.93), p<0.001). The mean difference between the minimum pad weight leakage and maximum leakage per patient was 133.4g (95% CI 80.4-186.5). The mean increase in 24-hour leakage for a one-point increase in self-reported activity level was 118.0g (95% CI 74.3-161.7, p<0.001). Pad weights also varied significantly when self-reported activity levels did not differ (mean difference 51.2g (95% CI 30.3-72.1), p<0.001). Conclusions: 24-hour pad weight leakage may vary significantly on different days of collection. This variation is more pronounced with changes in activity level. Taking into account patient activity level may enhance the predictive value of pad weight testing.