Specificity of psychological treatments for bulimia nervosa and binge eating disorder? A meta-analysis of direct comparisons

Treatment guidelines state that cognitive–behavioral therapy (CBT) and interpersonal therapy are the best-supported psychotherapies for bulimia nervosa (BN) and that CBT is the preferred psychological treatment for binge eating disorder (BED). However, no meta-analysis which both examined direct comparisons between psychological treatments for BN and BED and considered the role of moderating variables, such as the degree to which psychotherapy was bona fide, has previously been conducted Thus, such an analysis was undertaken. We included 77 comparisons reported in 53 studies. The results indicated that: (a) bona fide therapies outperformed non-bona fide treatments, (b) bona fide CBT outperformed bona fide non-CBT interventions by a statistically significant margin (only approaching statistical significance for BN and BED when examined individually), but many of these trials had confounds which limited their internal validity, (c) full CBT treatments offered no benefit over their components, and (d) the distribution of effect size differences between bona fide CBT treatments was homogeneously distributed around zero. These findings provide little support for treatment specificity in psychotherapy for BN and BED. ► 53 studies with 77 direct comparisons were included in the meta-analysis. ► Bona fide CBT outperformed bona fide non-CBT; internal validity was questionable. ► Full CBT packages performed no better than their components. ► Various CBT treatments yielded roughly equivalent effects. ► There was little evidence for treatment specificity in psychotherapies for BN or BED.