P1013 Placebo rates in Crohn's disease: An individual patient data meta-analysis from multiple randomised controlled trials

Abstract

Abstract Background Estimating placebo rates and their determinants is essential for designing efficient randomised clinical trials (RCTs) in inflammatory bowel disease. We conducted an individual patient data (IPD) meta-analysis of placebo data from RCTs in Crohn’s disease (CD). Methods MEDLINE, Embase, and CENTRAL were searched from 01/2010 to 01/2020 for contemporary phase 2 and 3 placebo-controlled RCTs of biologics in moderate-to-severe CD. De-identified IPD from eligible trials that were available through the Vivli and Yale University Open Data Access data-sharing platforms were obtained. Primary outcomes were placebo clinical response and remission. Pooled placebo rates and 95% CIs were estimated using a 2-stage meta-analytical approach. Significant patient-level factors (P<0.05) associated with placebo rates were identified using regression analyses. Results Placebo IPD were available from 8 induction (n=1147) and 4 maintenance trials (n=524). Pooled placebo clinical response and remission rates varied based on outcome definition and prior biologic exposure (Figure). In induction trials, overall placebo response and remission rates were 27% (95% CI 23-32%) and 10% (95% CI 8-14%), respectively. Among bio-exposed patients, placebo response and remission rates were 27% (95% CI 16-40%) and 9% (95% CI 6-15%), respectively, compared with 29% (95% CI 24-34%) and 11% (95% CI 8-15%) for bio-naïve patients. Overall placebo response and remission rates in maintenance trials were 32% (95% CI 23%-42%) and 22% (95% CI 14-33%), respectively. Corresponding placebo response and remission rates for bio-exposed patients were 21% (95% CI 8-46%) and 17% (95% CI 11-25%), and 36% (95% CI 28-44%) and 24% (95% CI 15-36%) for bio-naïve patients. Placebo rates were lowest when response was defined as a ≥100-point decrease from baseline in the Crohn's Disease Activity Index (CDAI) score, and when remission was defined using stool frequency (≤1.5) and abdominal pain (≤1) subscores. Higher baseline C-reactive protein concentrations were associated with lower odds of placebo response and remission, while higher baseline albumin levels increased the odds of these outcomes (Table). Increased baseline CDAI and 2-item patient-reported outcome (PRO2) scores predicted higher odds of placebo response in induction trials, yet this reduced the odds of remission in induction trials and of both outcomes in maintenance trials. Prior failure to tumour necrosis factor (TNF) antagonist therapy was more predictive than prior TNF antagonist/biologic exposure for reducing the odds of placebo response and remission. Conclusion Placebo rates and the patient-level factors influencing them vary according to study design, clinical outcome measure and outcome definitions.