Duration of Antimuscarinic Administration for Treatment of Overactive Bladder Before Which One Can Assess Efficacy: An Analysis of Predictive Factors

Purpose: To determine the duration of antimuscarinic therapy for overactive bladder syndrome (OAB) appropriate for assessment of the efficacy of treatment, and to evaluate the possible predictive factors for response to therapy. Methods: All OAB patients who visited a urology outpatient clinic of a tertiary referral center and who were prescribed 5 mg of solifenacin or 4 mg of tolterodine extended release capsules daily were enrolled in the study. Patients were asked to continue therapy for 6 months. All enrolled patients completed the patient perception of bladder condition, overactive bladder symptom score (OABSS), and the modified Indevus Urgency Severity Scale questionnaires. All patients underwent uroflowmetry. Results: A total of 164 patients were enrolled and 125 patients (76%) had at least one follow-up visit. The mean follow-up interval was 1 month (range, 0.5–6 months). Sixty-two patients (49.6%; 95% confidence interval [CI], 40.7–58.5) responded to antimuscarinic treatment. The median time for the onset of response was 3 months (95% CI, 1–6). Multivariate Cox proportional-hazards model revealed that elevated baseline OABSS was an independent predictor of responsiveness to therapy. Receiver operating characteristic (ROC) curve analysis revealed an optimal OABSS cutoff value of ≥7, with an area under the ROC curve of 0.79 (95% CI, 0.70–0.88; sensitivity, 91.9%; specificity, 60.7%). Conclusions: The median time for a therapeutic response was 3 months, and OABSS was the only predictor for responsiveness. These findings may serve as a guideline when prescribing antimuscarinic treatment for OAB patients