Mirabegron as Add-On Treatment to Solifenacin in Patients with Incontinent Overactive Bladder and an Inadequate Response to Solifenacin Monotherapy: Responder Analyses and Patient-Reported Outcomes from the BESIDE Study [corrected].

Purpose: We investigated improvements in overactive bladder and patient reported outcomes in patients with overactive bladder and refractory incontinence treated with mirabegron 50 mg plus solifenacin 5 mg vs solifenacin 5 or 10 mg. Materials and

Methods: Patients with overactive bladder who were incontinent despite 4 weeks of single-blind daily solifenacin 5 mg were randomized 1:1:1 to a double-blind daily combination of mirabegron 50 mg/solifenacin 5 mg, or solifenacin 5 or 10 mg for 12 weeks. The mirabegron dose was increased from 25 to 50 mg after week 4. Symptom bother, health related quality of life and patient perception of bladder condition were assessed by OAB-q (Overactive Bladder Questionnaire) and the PPBC (Patient Perception of Bladder Condition) questionnaire, respectively. Responder rates were based on a 50% reduction in daily incontinence, zero incontinence episodes and fewer than 8 micturitions per 24 hours with minimal important differences in OAB-q and PPBC.

Results: Overall 2,174 patients with a median age of 59 years were randomized, including 727 to the combination, 728 to solifenacin 5 mg and 719 to solifenacin 10 mg. Symptom bother, total health related quality of life and its subscales (coping, concern and social), and PPBC were significantly improved with combination vs solifenacin monotherapy (p <0.05). The odds of achieving clinically meaningful improvements in incontinence, micturition frequency, symptom bother, health related quality of life and PPBC were significantly higher for combination than solifenacin monotherapy. The odds of becoming continent was 47% and 28% higher for combination vs solifenacin 5 and 10 mg (OR 1.47, 95% CI 1.17-1.84, p = 0.001 and OR 1.28; 95% CI 1.02-1.61, p = 0.033, respectively).

Conclusions: Significantly more patients on the combination achieved clinically meaningful improvements in incontinence and micturition frequency. Improvements were accompanied by similar improvements in PPBC, symptom bother and health related quality of life.