Urgency-free time interval as primary endpoint for evaluating the outcome of a randomized OAB treatment

Introduction and hypothesis: This study was conducted to determine whether urgency-free interval (UFI) was effective to evaluate the outcome of overactive bladder (OAB) and the correlation of changes between this parameter and urgency episodes. Methods: A randomized placebo-controlled trial was conducted involving 73 women with OAB. The interventions for a 12-week period included a vaginal electric stimulation and oxybutynin (2.5 mg) or placebo three times per day. Identical preintervention and postintervention assessments included the measurement of UFI and warning time (WT). The King's Health Questionnaire, Spearman's correlation coefficient (SCC), Kruskal-Wallis, Mann-Whitney U, and Wilcoxon-signed rank tests were used for analysis. Results: A positive and significant correlation between the improvements of WT and UFI was noted in the oxybutynin group (p = 0.009). In all groups, none of the SCC revealed significant correlation between the improvement of UFI and urgency episodes (all p≥0.145). Conclusions: The efficacy of UFI in evaluating treatment outcome of OAB was comparable with that of WT in selected modality.