Usefulness of a Novel Classification Based on Perioperative Changes of Membranous Urethral Length Using Hierarchical Cluster Analysis of Urinary Incontinence and Overactive Bladder Symptoms after Robot-Assisted Radical Prostatectomy: A Prospective Observational Study

Aims The aim of the present study was to construct a novel classification based on perioperative changes of membranous urethral length (MUL) using hierarchical cluster analysis to predict urinary incontinence (UI) and overactive bladder (OAB) symptoms after robot-assisted radical prostatectomy (RARP). Methods A total of 299 patients who underwent RARP with complete pre and postoperative MUL data were included in the present study. Hierarchical cluster analysis was performed to identify the groups with similar perioperative MUL and prostate size. UI and OAB symptoms after RARP were evaluated in each cluster for 12 months after RARP. Results Four groups were identified by the cluster analysis of these factors: preservation of MUL type (cluster 1, n = 92); standard type (cluster 2, n = 137); large prostate type (cluster 3, n = 23); and loss of MUL type (cluster 4, n = 47). Although there was significantly more UI in clusters 3 and 4 than in clusters 1 and 2 up to 3 months after RARP, UI improvement was the most delayed in cluster 3. Improvement of OAB symptoms was also most delayed in cluster 3. Urinary quality of life (QOL) was significantly worse in cluster 4 than in clusters 1 and 2. Conclusions Cluster analysis successfully classified patients after RARP into four characteristic groups based on perioperative MUL. Recovery from UI and OAB symptoms and urinary QOL after RARP were significantly different among these groups. This classification based on cluster analysis might be useful to predict recovery from UI and OAB symptoms when following QOL after RARP.