Adverse effects and discontinuation rates for darifenacin in overactive urinary bladder: a systematic review and meta-analysis of randomized controlled trials

The aim of this systematic review and meta-analysis was to identify the discontinuation rates, and incidence of adverse effects (AEs) for patients on prescribed oral darifenacin for the treatment of overactive bladder (OAB). PubMed, Embase, and Cochrane CENTRAL were searched for randomized controlled trials. A risk of bias assessment and a Grading of Recommendations Assessment, Development and Evaluation were used to assess the certainty of evidence. The primary outcome was OAB patient discontinuation and AEs in darifenacin and placebo groups, and reporting was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Seven studies of 2381 participants were included. The most reported AEs were dry mouth and constipation. There were more participants with dry mouth in the darifenacin group compared to the placebo (p < 0.0001, moderate level of certainty) and a dose-response pattern was observed. There was a higher rate of constipation in the darifenacin group than in the placebo group (p < 0.0001, high level of certainty), with evidence of a dose-response pattern. There were no differences between the darifenacin group and the placebo group in total discontinuations (RR 0.93, 95% CI 0.72-1.20) or undefined discontinuations (RR 0.85, 95% CI 0.54-1.33). Studies were generally rated at low or unclear risk of bias for most domains. While patients prescribed darifenacin do experience a higher rate of side-effects, which increases with dose, they seem to be tolerated as both the intervention and placebo groups reported similar rates of discontinuation.