Assessment of different continence definitions in the context of the randomized multicenter prospective LAP-01 trial—Does the best definition change over time?

A uniform definition of continence is urgently needed to allow the comparison of study results and to estimate patient outcomes after radical prostatectomy (RP). To identify a practical definition that includes both objective and subjective aspects in a tangible way, we assessed different continence definitions and evaluated which best reflects the patients’ subjective perception of continence.

Our analyses included 718 patients that underwent either robot-assisted radical prostatectomy (RARP) or laparoscopic radical prostatectomy (LRP) in a multicenter randomized patient-blinded trial. Continence was assessed through patient questionnaires prior to and at 3, 6 and 12 months after surgery which included the number of pads used per day, the ICIQ-SF and the question “Do you suffer from incontinence? (yes/no)” to assess subjective continence. We used Krippendorff’s Alpha to calculate the agreement of different continence definitions with the subjective perception.

At 3 months, the “0/safety pad” definition shows the highest agreement by alpha = 0.70 (vs. 0.63 for “0 pads” and 0.37 for “0–1 pad”). At 6 and 12 months “0 pads” is the better match, with alpha values of 0.69 (vs. 0.62 and 0.31) after 6 months and 0.70 (vs. 0.65 and 0.32) after 12 months. The ICIQ-SF score shows good correlation with the subjective continence at 3 months (alpha = − 0.79), the coefficient then decreasing to − 0.69 and − 0.59 at 6 and 12 months.

The best continence definition according to the patients’ perspective changes over time, “0 pads” being the superior criterion in the long-term. We recommend using the 0-pad definition for standardized continence reporting, as it is simple yet as accurate as possible given the inevitably high subjectivity of continence perception.

Trial registration The LAP-01 trial was registered with the U.S. National Library of Medicine clinical trial registry (clinicaltrials.gov), NCT number: NCT03682146, and with the German Clinical Trial registry (Deutsches Register Klinischer Studien), DRKS ID number: DRKS00007138