Supplementary Material for: Efficacy of App-Based Cognitive Behavioral Therapy for Body Dysmorphic Disorder with Coach Support: Initial Randomized Controlled Clinical Trial

Introduction: Body dysmorphic disorder (BDD) is severe, chronic, and undertreated. Apps could substantially improve treatment access. Objective: We provide an initial test of the usability and efficacy of coach-supported app-based cognitive behavioral therapy (CBT) for BDD. The Perspectives app covers core treatment components: psychoeducation, cognitive restructuring, exposure with response prevention, mindfulness, attention retraining, and relapse prevention. Methods: A randomized waitlist-controlled trial was conducted. Adults (N = 80) with primary BDD were assigned to 12 weeks of Perspectives or waitlist. Coaches promoted engagement and answered questions via in-app messaging and phone calls. BDD severity was measured at baseline, mid-treatment, and end of treatment by blinded independent evaluators (Yale-Brown Obsessive Compulsive Scale Modified for BDD; BDD-YBOCS). Secondary outcomes included BDD-related insight, depression, quality of life, and functioning. Results: App uptake and satisfaction were high. In intent-to-treat analyses, Perspectives app-based CBT was associated with significantly lower BDD-YBOCS severity at end of treatment (M [SD]: 16.8 [7.5]) compared to the waitlist (26.7 [6.2]; p < 0.001, d = 1.44). App-based CBT was associated with greater improvements across all secondary measures, with medium to large effects. Conclusions: Perspectives, supported by a bachelor’s-level coach, is an efficacious, scalable treatment for adults with BDD.