Relationship between changes in CP/CPPS symptoms and erectile function over 12 weeks: a retrospective cohort study

The extent to which short-term changes in chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) symptoms and erectile function align remains uncertain. We retrospectively analyzed 122 men with CP/CPPS who reported sexual activity during both questionnaire reference periods and had complete baseline and week-12 National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and 5-item International Index of Erectile Function (IIEF-5) assessments during usual care. Improvements were defined as baseline minus week-12 NIH-CPSI and week-12 minus baseline IIEF-5. Their continuous association was evaluated using Spearman correlation with 10,000 bootstrap resamples and baseline-adjusted analysis of covariance. Threshold-based classifications were secondary and exploratory. Mean NIH-CPSI and IIEF-5 improvements were 6.0 points (95% CI 5.3 to 6.6) and 1.9 points (95% CI 1.3 to 2.5), respectively. Improvements were modestly correlated (Spearman ρ = 0.32, bootstrap 95% CI 0.14 to 0.48). In the unadjusted improvement-on-improvement model, each 1-point greater NIH-CPSI improvement corresponded to a 0.33-point greater IIEF-5 improvement (95% CI 0.17 to 0.49). In the adjusted analysis of covariance with week-12 IIEF-5 as the outcome, the corresponding coefficient was 0.33 (95% CI 0.16 to 0.51). Among 104 men with baseline IIEF-5-defined erectile dysfunction, 71 (68.3%) remained at or below the cutoff at week 12. Among men with evaluable paired assessments, changes in CP/CPPS symptoms and erectile function were only partially aligned. NIH-CPSI improvement should not be used as a proxy for concurrent erectile-function improvement. Direct assessment of erectile function remains necessary, and the findings should not be interpreted as treatment effects.