Placebo Rates in Crohn's Disease Randomized Clinical Trials: An Individual Patient Data Meta-Analysis.

Background & Aims: Understanding placebo rates is critical for efficient clinical trial design. We assessed placebo rates and associated factors using individual patient data from Crohn's disease trials.

Methods: We conducted a meta-analysis of phase 2/3 placebo-controlled trials evaluating advanced therapies in moderate to severe Crohn's disease (2010-2021). Deidentified individual patient data were obtained through Vivli Inc and the Yale University Open Data Access Project. Primary outcomes were clinical response and remission. Pooled placebo rates and 95% confidence intervals (CIs) were estimated using 1- and 2-stage meta-analytic approaches. Regression analyses identified patient-level factors associated with placebo rates.

Results: Analysis of individual patient data from 8 induction (n = 1147) and 4 maintenance (n = 524) trials showed overall placebo clinical response and remission rates for induction were 27% (95% CI, 23%-32%) and 10% (95% CI, 8%-14%), respectively, and 32% (95% CI, 23%-42%) and 22% (95% CI, 14%-33%) for maintenance, respectively. Among biologic (bio)-naïve patients, placebo response and remission rates during induction were 29% (95% CI, 24%-35%) and 11% (95% CI, 8%-15%) respectively, and 26% (95% CI, 20%-33%) and 10% (95% CI, 8%-14%) for biologic (bio)-exposed patients, respectively. During maintenance, biologic-naïve response and remission rates were 41% (95% CI, 34%-48%) and 32% (95% CI, 24%-40%), respectively, and 29% (95% CI, 24%-34%) and 16% (95% CI, 13%-21%) for bio-exposed, respectively. Higher baseline C-reactive protein concentration predicted lower placebo rates, whereas higher baseline albumin levels and body mass index increased the odds of placebo outcomes. Increased baseline Crohn's Disease Activity Index and 2-item patient-reported outcome scores predicted higher response rates in induction, lower response rates in maintenance, and lower remission rates in induction and maintenance.

Conclusions: Patient- and trial-level characteristics influence placebo rates in Crohn's disease trials. Careful implementation of eligibility criteria, outcome definitions, and patient stratification may reduce placebo rates.