Meta-Analysis of the Placebo Rates of Clinical Relapse and Severe Endoscopic Recurrence in Postoperative Crohn's Disease

Backgrounds & Aims: The benefit of therapy for prevention of postoperative recurrence of Crohn's disease (CD) is limited. Clinical relapse and severe endoscopic recurrence are the main outcomes in the evaluation of trials on prevention of recurrence. The aim of this meta-analysis was to focus on knowledge of the placebo rates of relapse and recurrence in postoperative CD and to identify factors influencing these rates. Methods: We performed a meta-analysis of placebo-controlled, randomized clinical trials, evaluating therapies for postoperative maintenance of CD identified on MEDLINE from 1990 to 2006. Primary outcomes were clinical relapse and severe endoscopic recurrence. Results: The pooled estimate of the placebo relapse rate was 23.7% (95% confidence interval [CI], 13-35; range 0-78). There was a statistically significant heterogeneity among studies (P < .0001). Heterogeneity in clinical relapse was present even if the trials were stratified according to the time of outcome. The pooled estimate of the severe endoscopic recurrence rate was 50.2% (95% CI, 28-73; range, 30-79). There was significant heterogeneity among the studies (P = .00038). This heterogeneity was less apparent in studies carried out within 12 months. The logistic analysis identified only duration of follow-up as a variable associated with different placebo relapse rates. No variable was identified as a predictor of a placebo endoscopic recurrence rate. Conclusions: There is significant heterogeneity among placebo rates in postoperative CD. No single design variable was identified that explained the heterogeneity in placebo outcomes for clinical or endoscopic recurrence.