Histological Remission Placebo Rates in Ulcerative Colitis Trials: A Systematic Review and Meta-analysis.

Placebo histological remission rates range from 13% to 19% in UC RCTs, but studies are highly heterogeneous. Factors found to influence placebo rates include presence of background medications, the drug used, and the disease severity. These observations inform future trial designs to minimize placebo rates and reduce heterogeneity.