Meta-analysis of the placebo response in ulcerative colitis

Purpose The placebo response rate in randomized controlled trials (RCTs) in ulcerative colitis (UC) varies from 0 to 76%. The aims of this study were to quantify the pooled placebo response rate and identify the factors affecting it. Methods We performed a meta-analysis of 110 RCTs carried out between 1955 and 2005 and published in English. Regression analysis was used to identify factors significantly modifying placebo response. Results The pooled placebo remission rate was 23% (95%CI: 18.4-28%) and the pooled placebo improvement rate was 32.1% (95%CI: 28.1-36.3%). Multivariate analysis showed that the country where the study was performed (P = 0.025 for placebo remission and P = 0.0083 for placebo response rates) significantly influenced the placebo remission and response rates. Conclusion Placebo remission and response rates in RCTs of UC are highly variable and are significantly influenced by the country in which the RCT is performed.