Nocebo Response in the Pharmacological Management of Overactive Bladder: A Systematic Review and Meta-analysis

The role of a nocebo response in managing urology patients is unclear. To assess the nocebo response in randomized placebo-controlled overactive bladder (OAB) trials of pharmacological treatment by investigating the adverse events in the placebo arms. PubMed, Scopus, Embase, and Cochrane Central Register of Controlled Trials were searched to identify potential randomized controlled trials published from 1998 to November 2019. After evaluating the risk of bias in the selected studies, all selected full-text articles were included due to their overall acceptable quality. We extracted the event rate of the most commonly reported adverse events in the placebo arms of OAB trials, and finally, we performed a meta-analysis to calculate the cumulative rate of certain adverse events. The primary outcomes were the event rate of adverse events in the placebo arms of OAB trials of pharmacological treatment, and differences in adverse events in the placebo groups based on drug type and routes of administration. After a systematic search and risk of bias assessment, 57 trials comprising 15 446 patients were included in this systematic review. We selected 13 commonly reported adverse events for the meta-analysis. Owing to the possible differences in study samples and design, we used a random model for the analysis. The average age of the patients was 59.5 yr and 79.8% were female. Dry mouth was the most commonly evaluated adverse event reported in 57 studies comprising 15 324 patients; the mean event rate was 4.9% (95% confidence interval [CI] 0.042–0.057, p