To evaluate the correlation between three- and six-week post-operative 24-hour pad weight, daily pad number and the International Consultation on Incontinence Questionnaires for Male Lower Urinary Tract (ICIQ-MLUTS), ICIQ-Short Form (ICIQ-SF) and UCLA Prostate Cancer Index (UCLA-PCI) in patients undergoing robotic-assisted radical prostatectomy (RARP).

This original prospective study included patients undergoing RARP between February and November 2019. Patients completed a 24-hour pad test, assessing pad weight and number, and three validated patient reported outcome measures (PROMs); the ICIQ-MLUTS, ICIQ-SF and UCLA-PCI, pre-operatively and at three and six weeks post-operatively.

A total of 47 patients were included in the study. There was a strong correlation between 24-hour pad weight and the ICIQ-SF at three weeks (r=0.71, p<.001) and six weeks (r=0.68, p<.001). There was a strong correlation between 24-hour pad weight and ICIQ-MLUTS incontinence (r=0.80, p<.01) and incontinence QoL burden (r=0.79, p<.01) at six weeks. There was a moderate correlation between the 24-hour pad weight and UCLA-PCI urinary function (r=0.58, p<.001) and urinary QoL burden (r=0.66, p<.001) at six weeks. The correlation between pad number and 24-hour pad weight was weak at six weeks (r=0.34, p<.001).

The 24-hour pad weight test is widely accepted as the gold standard for objective measurement of incontinence but can be burdensome for patients. To date, there is no consensus on the best substitute for the 24-hour pad weight test for PPI assessment. This study evaluated multiple methods of assessing PPI to determine the most accurate and reliable. Our study demonstrates that PROMs are reliable substitutes for the 24-hour pad weight test for routine PPI assessment in the early post-operative period. 

The use of the daily pad number as a substitute for 24-hour pad weight remains controversial. We found weak correlation between pad number and 24-hour pad weight at three weeks and six weeks post-operatively. This is in line with previous studies reporting that the pad number is not a reliable measure of incontinence [1]. Patients may change pads for reasons unrelated to incontinence, including differing acceptable hygiene and pad wetness levels, convenience and financial or physical access to pads. As previous studies did not evaluate pad number reliability specifically for PPI, our study serves to validate this finding in a post-prostatectomy population.

PROMs may be used as a substitute for the 24-hour pad weight test for post-prostatectomy incontinence (PPI) assessments in the early post-RARP period. The ICIQ-SF and UCLA-PCI urinary function and QoL scores correlate with 24-hour pad weight. However, the ICIQ-MLUTS incontinence and QoL scores provide the strongest correlation with PPI.

Sacco E, Bientinesi R, Gandi C, Di Gianfrancesco L, Pierconti F, Racioppi M et al. Patient pad count is a poor measure of urinary incontinence compared with 48-h pad test: results of a large-scale multicentre study. BJU International. 2018;123(5A):E69-E78.