Do patient characteristics predict which patients with overactive bladder benefit from a higher fesoterodine dose?

Introduction and hypothesis: We sought to determine whether baseline characteristics predict which overactive bladder (OAB) patients benefit from fesoterodine 8 mg versus 4 mg. Methods: In double-blind, placebo-controlled, flexible-dose trials, baseline characteristics of OAB patients with ≥ 1 urgency urinary incontinence (UUI) episodes/24 h who escalated from fesoterodine 4 mg to 8 mg were evaluated. Possible dose-escalation predictors (age; sex; previous antimuscarinic use; UUI, micturitions, and urgency episodes/24 h; race; body mass index; time to dose escalation; OAB duration) were compared in escalators versus non-escalators. Patients from fixed-dose trials with dose-escalator characteristics were identified (matched dose-escalator sample) to assess changes from baseline with fesoterodine 4 mg, 8 mg, and placebo. Results: In flexible-dose trials, significant predictors of fesoterodine dose escalation were younger age (≤ 65.8 years), greater number of baseline micturitions (≥ 13.1) and urgency episodes/24 h (≥ 10.9), greater OAB duration (≥ 9.1 years), and more frequent previous antimuscarinic use (58.3%), but not baseline UUI episodes/24 h. In the matched dose-escalator sample (fesoterodine 4 mg: n = 215; 8 mg: n = 198; placebo: n = 217), change from baseline in UUI episodes significantly improved with fesoterodine 8 mg versus 4 mg (P = 0.043) and with both doses versus placebo (P < 0.001). Dry mouth and constipation rates were higher with fesoterodine 8 mg. Conclusions: Dose-escalator patients had a significantly greater UUI response with fesoterodine 8 mg versus 4 mg. Given the potential for adverse events, fesoterodine 4 mg is recommended to start; however, patients with UUI and identified predictors may benefit from initial treatment with fesoterodine 8 mg or rapid dose escalation.