Meta-analysis of the effects of cognitive-behavioral therapy for binge-eating-type disorders on abstinence rates in nonrandomized effectiveness studies: comparable outcomes to randomized, controlled trials?

OBJECTIVE: The efficacy of cognitive-behavioral therapy (CBT) for eating disorders is well-established. The extent to which CBT tested in controlled research settings generalizes to real-world circumstances is unknown. We conducted a meta-analysis of nonrandomized studies of CBT for eating disorders, with three aims: (a) to estimate the prevalence of patients who achieve binge-purge abstinence after CBT in routine practice; (b) to compare these estimates with those derived from two recent meta-analyses of randomized controlled trials (RCTs) of CBT for bulimia nervosa (BN) and binge-eating disorder (BED); (c) to examine whether the degree of clinical representativeness of studies was associated with effect sizes. METHOD: Twenty-seven studies, mainly involving BN, were included. Pooled event rates were calculated using random effects models. RESULTS: The percentage of treatment completers who achieved abstinence at post-treatment was 42.1% (95% CI = 34.7-50.0). The intention-to-treat (ITT) estimate was lower (34.6% [95% CI = 29.3-40.4]). However, abstinence rates varied across diagnoses, such that the completer and ITT analysis abstinence estimates were larger for BED samples (completer = 50.2%, 95% CI = 29.4-70.9; ITT = 47.2%, 95% CI = 29.8-65.2) than for BN (completer = 37.4%, 95% CI = 29.1-46.5; ITT = 29.8%, 95% CI = 24.9-35.3) and atypical eating disorder samples (completer = 37.8%, 95% CI = 20.2-59.3; ITT = 28.8%, 95% CI = 18.2-42.4). No relationship between the degree of clinical representativeness and the effect size was observed, and our estimates were highly comparable to those observed in recent meta-analyses of RCTs. DISCUSSION: Findings suggest that CBT for eating disorder can be effectively delivered in real-world settings. This study provides evidence for the generalizability of CBT from controlled research settings to routine clinical services.