Mediation analysis of adherence to pelvic floor muscle training and weekly self-monitoring on urinary symptoms in men with localized prostate cancer A secondary analysis of the Prostate Cancer-Patient Empowerment Program (PC-PEP) randomized controlled trial.

INTRODUCTION

Men treated curatively for localized prostate cancer often experience urinary complications that impair quality of life. The Prostate Cancer-Patient Empowerment Program (PC-PEP) is a six-month, digital intervention integrating pelvic floor muscle training (PFMT), fitness, nutrition, and intimacy support. While early initiation of PC-PEP improves urinary outcomes, the influence of adherence remains unclear. This mediation analysis examined whether reported PFMT duration and engagement with self-monitoring mediate the association between timing of PC-PEP delivery (early vs. late) and urinary outcomes.

METHODS

In a randomized, crossover trial, 128 men with localized prostate cancer were assigned to receive PC-PEP immediately (early group, n=66) or after six months of standard care (late group, n=62). Urinary outcomes were assessed using the Expanded Prostate Cancer Index Composite (EPIC) and International Prostate Symptom Score (IPSS). Weekly compliance surveys tracked engagement. Mediation and moderated mediation analyses adjusted for age, comorbidity, treatment modality, and baseline urinary function.

RESULTS

Mean reported weekly PFMT duration did not differ between groups. The early group had higher compliance survey completion (98.8% vs. 64.1%, p<0.001) and higher post-intervention EPIC urinary incontinence scores (81.5±21.9 vs. 68.2±17.0, p<0.001), indicating better continence. Compliance survey completion mediated 41% of the association between early intervention and post-intervention EPIC urinary incontinence scores. No significant mediation was observed for IPSS or EPIC irritative/obstructive scores. Treatment modality did not moderate effects.

CONCLUSIONS

Early initiation of PC-PEP was associated with greater engagement in structured self-monitoring, which mediated improvements in urinary continence independent of reported PFMT duration. Integrating early patient activation and digital self-monitoring into post-treatment care may improve urinary continence outcomes and support scalable rehabilitation.