Su1083 Can Crohn's Disease Activity Index Differentiate Clinical Remission Induced by Placebo Versus Biologics Treatment? – Analyses of Six Clinical Trials for Crohn's Disease

Crohn's Disease Activity Index (CDAI), a composite score based on eight subcomponents, has been used to assess the efficacy of drugs for Crohn's Disease (CD). However, the existence of a high placebo rate has been a challenge in clinical trials that have used CDAI as the primary endpoint. To better understand the placebo effect, we evaluated the change from baseline in CDAI and its subcomponents in patients who achieved remission in response to placebo or active treatment. Patient-level data were reviewed from six phase 2 and phase 3 clinical trials that were submitted to FDA in support of three biological products for treatment of CD. Clinical remission was defined as CDAI < 150 in all six trials, and the induction of remission was assessed at a pre-defined time-point. We evaluated the overall change from baseline in CDAI and its subcomponents in achieving remission and identified major contributing subcomponents. We compared changes in CDAI and major contributing subcomponents in patients who achieved remission by placebo or active treatments. Mean baseline CDAI across trials ranged from 294 to 313 in placebo groups and 295 to 312 in active treatment groups. The rate of remission ranged from 8.2% to 30.3% among the placebo groups and 22.2% to 39.6% among the active treatment groups across six trials. For remitters, the average decrease from baseline in CDAI score was 167 in the placebo groups and 186 in active treatment groups across six trials. Greater than 80% of the decrease in the overall CDAI score was attributed to a decrease in three subcomponent scores: general well-being [WB] (40%), abdominal pain [AP] (25%), and stool frequency [SF] (22%). The relative contribution of each subcomponent to achieve remission was similar between placebo