How many individuals achieve symptom abstinence following psychological treatments for bulimia nervosa? A meta-analytic review

OBJECTIVES: It is unclear how many patients with bulimia nervosa (BN) completely abstain from the core behavioral symptoms after receiving psychological treatment. The present meta-analysis of randomized controlled trials (RCTs) aimed to (a) estimate the prevalence of patients who abstain from binge eating and/or purging following all psychological treatments for BN, and (b) test whether these abstinence estimates are moderated by the type of treatment modality delivered, the definition of abstinence applied, and trial quality. METHOD: Forty-five RCTs were included, with 78 psychotherapy conditions. Pooled event rates were calculated using random effects models. RESULTS: At post-treatment, the total weighted percentage of treatment-completers who achieved abstinence was 35.4% (95% CI = 29.6, 41.7), while the total weighted percentage of abstinence for all randomized patients (intention-to-treat) was 29.9% (95% CI = 25.7, 33.2). Abstinence estimates were highest in trials that used behavioral-based treatments (e.g., cognitive-behavioral therapy, behavior therapy). There was also evidence that guided self-help interventions produced the lowest post-treatment abstinence rates, but with no difference at follow-up from clinician-led treatments, and studies that used a shorter timeframe for defining abstinence (i.e., 14 days symptom-free compared to 28-days symptom-free) produced the highest abstinence rates. Abstinence estimates at follow-up for both the completer (34.6%; 95% CI = 29.3, 40.2) and intention-to-treat (28.6%; 95% CI = 25.1, 32.3) analyses were essentially the same as the post-treatment estimates. DISCUSSION: Over 60% of patients fail to fully abstain from core BN symptoms even after receiving our most empirically-supported treatments. The present findings highlight the urgency toward improving the effectiveness of psychological treatments for BN.