Comparative efficacy and safety of medical treatments for the management of overactive bladder: a systematic literature review and mixed treatment comparison

Context: Overactive bladder (OAB) treatment guidelines recommend antimuscarinics as first-line pharmacologic therapy. Mirabegron is a first-in-class β3-adrenoceptor agonist licensed for the treatment of OAB and has shown to be well tolerated and effective in the treatment of OAB symptoms.

Objective: To assess the relative efficacy and tolerability of OAB medications, specifically mirabegron 50 mg versus antimuscarinics in patients with OAB.

Evidence acquisition: A systematic literature search was performed on published peer-reviewed articles from 2000 to 2013. This review included randomised controlled trials (RCTs) studying changes in symptoms (micturition frequency, incontinence, and urgency urinary incontinence [UUI] episodes) and incidence of the most frequently reported adverse events (dry mouth, constipation) associated with current OAB medications. The following drugs were considered in addition to mirabegron: darifenacin, tolterodine immediate release (IR) and extended release (ER), oxybutynin IR/ER, trospium, solifenacin, and fesoterodine. Bayesian mixed treatment comparisons (MTCs) were performed for efficacy (micturition, incontinence, UUI) and tolerability (dry mouth, constipation, blurred vision).

Evidence synthesis: Overall, 44 RCTs involving 27,309 patients were included. The MTCs showed that mirabegron 50 mg was as efficacious as antimuscarinics in reducing the frequency of micturition incontinence and UUI episodes, with the exception of solifenacin 10 mg that was more efficacious than mirabegron 50 mg in improving micturition frequency and frequency of UUI. Mirabegron 50 mg had an incidence of dry mouth similar to placebo and significantly lower than all included antimuscarinics.

Conclusions: Mirabegron 50 mg had similar efficacy to most antimuscarinics and lower incidence of dry mouth, the most common adverse event reported with antimuscarinics and one of the main causes of discontinuation of treatment. Despite being a powerful tool for evidence-based health care evaluation, the Bayesian MTC method has limitations. Further head-to-head comparisons between mirabegron and antimuscarinics should be conducted to confirm our results.