Psychiatric comorbidity as predictor and moderator of binge-eating disorder treatment outcomes: an analysis of aggregated randomized controlled trials

Background Psychiatric comorbidity is common in binge-eating disorder (BED) but effects on treatment outcomes are unknown. The current study aimed to determine whether psychiatric comorbidity predicted or moderated BED treatment outcomes. Methods In total, 636 adults with BED in randomized-controlled trials (RCTs) were assessed prior, throughout, and posttreatment by doctoral research-clinicians using reliably-administered semi-structured interviews, self-report measures, and measured weight. Data were aggregated from RCTs testing cognitive-behavioral therapy, behavioral weight loss, multi-modal (combined pharmacological plus cognitive-behavioral/behavioral), and/or control conditions. Intent-to-treat analyses (all available data) tested comorbidity (mood, anxiety, 'any disorder' separately) as predictors and moderators of outcomes. Mixed-effects models tested comorbidity effects on binge-eating frequency, global eating-disorder psychopathology, and weight. Generalized estimating equation models tested binge-eating remission (zero binge-eating episodes during the past month; missing data imputed as failure). Results Overall, 41% of patients had current psychiatric comorbidity; 22% had mood and 23% had anxiety disorders. Psychiatric comorbidity did not significantly moderate the outcomes of specific treatments. Psychiatric comorbidity predicted worse eating-disorder psychopathology and higher binge-eating frequency across all treatments and timepoints. Patients with mood comorbidity were significantly less likely to remit than those without mood disorders (30% v. 41%). Psychiatric comorbidity neither predicted nor moderated weight loss. Conclusions Psychiatric comorbidity was associated with more severe BED psychopathology throughout treatment but did not moderate outcomes. Findings highlight the need to improve treatments for BED with psychiatric comorbidities but challenge perspectives that combining existing psychological and pharmacological interventions is warranted. Treatment research must identify more effective interventions for BED overall and for patients with comorbidities.