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BACKGROUND AND AIMS: Nocebo effects, adverse outcomes occurring in patients receiving inert therapy, contribute to adverse event AE reporting in randomized controlled trials RCTs. High placebo AE rates may result in inaccurate estimation of treatment-related AEs. We estimate the pooled rate of AEs in patients randomized to placebo compared to active therapy in inflammatory bowel disease IBD RCTs. METHODS: MEDLINE, EMBASE and CENTRAL were searched to March 1, 2017 for RCTs of conventional medical therapies for Crohn's disease CD or ulcerative colitis UC. Rates of AEs, serious AEs SAEs, AE-related trial withdrawal, infections and worsening IBD were pooled using a random-effects model. RESULTS: We included 124 CD n = 26 042 and 71 UC RCTs n = 16 798. The pooled placebo AE rate was 70.6% (95% confidence interval CI: 65.3%, 75.4%) and 54.5% 47.8%, 61.1% in CD and UC RCTs, respectively. There was no significant risk difference RD in AE, SAE or AE-related withdrawal rates between CD patients receiving placebo or active drug. A 1.6% 95% CI: 0.1%, 3.1% increase in AE rates was observed among UC patients randomized to active therapy. Patients receiving active therapy had a higher risk of infection (RD 1.0% 95% CI: 0.4%, 1.7% for CD, 2.9% 95% CI: 1.4%, 4.4% for UC) although a lower risk of worsening CD (RD -3.2% 95% CI: -4.8%, -1.5%) or UC (RD -3.7% 95% CI: -5.7%, -1.8%). CONCLUSIONS: AEs are commonly reported by patients randomized to either placebo or active treatment in IBD RCTs. Clinically relevant differences in AE, SAE and AE-related withdrawal were not observed.
Ma et al. (Fri,) studied this question.