Do patient characteristics predict responsiveness to treatment of overactive bladder with antimuscarinic agents?

Objective To determine clinical and demographic characteristics associated with antimuscarinic treatment response using a regression model. Methods Adults with overactive bladder (OAB) symptoms for >3 months and ≥1 urgency urinary incontinence (UUI) episode and ≥8 micturitions per 24 hours at baseline were randomized to fesoterodine (8 mg), tolterodine extended-release (4 mg), or placebo in two 12-week, double-blind, head-to-head studies. Fesoterodine-treated patients received 4 mg/d during the first week and 8 mg/d thereafter. Patients completed 3-day bladder diaries and the Overactive Bladder Questionnaire at baseline and week 12. Pooled data for changes from baseline to week 12 in winsorized UUI episodes, micturitions, and urgency episodes per 24 hours and Overactive Bladder Questionnaire Symptom Bother and health-related quality of life scores were analyzed posthoc using a regression model that selects outcome predictors from baseline values and patient characteristics while retaining baseline values and treatment, with stepwise inclusion of significant covariates and assessment of treatment interactions. Logistic regression was used for analysis of diary-dry rates. Results Younger age, lack of previous antimuscarinic treatment, shorter duration of OAB diagnosis, and female gender were common predictors of larger changes in outcomes from baseline to week 12. Baseline measures often interacted with treatment, such that poorer baseline outcomes were predictive of larger treatment differences. Longer duration since OAB diagnosis predicted greater treatment differences for UUI episodes and in diary-dry rate, and increased age predicted greater treatment differences for micturitions. Conclusion Symptom severity and duration, age, gender, and previous antimuscarinic pharmacotherapy impact the response to antimuscarinic treatment.