Longitudinal recovery patterns of penile length and the underexplored benefit of long-term phosphodiesterase-5 inhibitor use after radical prostatectomy

BACKGROUND: Penile length (PL) shortening is an underreported phenomenon following radical prostatectomy (RP) and risk factors are not fully explored. We aimed to describe longitudinal patterns of PL recovery and evaluate factors predicting complete return to baseline PL. METHODS: PL measurement was performed during a preoperative and postoperative follow-up visits at 7 days and 3, 6, 9, and 12 months. Patients who completely recovered (CR: N = 397) their preoperative stretched PL measured during at least one of their follow-up visits were compared to those with incomplete recovery (IR: N = 131). Recovery patterns were analyzed for both groups and were also compared in regards to demographics, nerve-sparing techniques, prostate size, cardiovascular risk profiles, and phosphodiesterase-5 inhibitor (PDE5i) uses. Logistic regression analyses were performed using age and other relevant clinicopathologic variables to predict PL recovery. RESULTS: 60.2% of the total study population regained their preoperative PL at 12 months. Average percent (length) differences from baseline were − 1.70% (− 0.25 cm) and − 16.42% (− 2.35 cm) in the CR and the IR groups, respectively (p < 0.001). Multivariate logistic regression demonstrated that younger age (OR 0.962; 95%CI 0.931–0.994; p = 0.019), high preoperative erectile function (EF) (OR 1.028; 95%CI 1.001–1.056; p = 0.046), and consistent PDE5i use (OR 1.998; 95%CI 1.166–3.425; p = 0.012) were independent predictors of CR. At 12-month follow up, PL difference for consistent PDE5iusers was statistically different from those who did not use PDE5i consistently (− 3.25%vs. -6.64%; P = 0.001). CONCLUSION: Age, preoperative EF, and consistent use of PDE5i were associated with complete recovery of baseline PL after RP. The therapeutic effect of PDE5i was most pronounced at 12-month visit, suggesting an added benefit with long-term use. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12894-018-0341-8) contains supplementary material, which is available to authorized users.