Evaluating the feasibility, acceptability, and preliminary effectiveness of interprofessional Enhanced Cognitive Behavior Therapy for anorexia nervosa and atypical anorexia nervosa: a pilot study

Objective: Enhanced Cognitive Behavior Therapy (CBT-E) is the leading outpatient treatment for eating disorders but is typically delivered by a single clinician and does not routinely incorporate interprofessional expertise. In broader healthcare settings, Interprofessional collaborative practice (IPCP), characterized by role clarity, shared values, structured communication, and teamwork, is associated with improved patient, clinician, and organizational outcomes. Interprofessional Enhanced Cognitive Behavior Therapy (CBT-IE) adapts CBT-E by embedding IPCP through co-delivery by a mental health professional and dietitian. This pilot evaluated the feasibility, acceptability, and preliminary effectiveness of CBT-IE for adults with anorexia nervosa (AN) and atypical AN in outpatient settings. Method: In this single-group mixed-methods pilot (ACTRN12622000305729), adults with AN or atypical AN were recruited from two Australian private practices and received up to 40 sessions over 12 months. Feasibility was assessed via recruitment, retention, and treatment dose, and explored alongside acceptability through post-treatment interviews. Preliminary effectiveness outcomes included body mass index (BMI), eating disorder psychopathology, psychosocial functioning, intuitive eating, and dietary intake. Results: Sixteen participants enrolled; 12 completed treatment (75% retention; mean 27.2 sessions). BMI increased significantly with a large effect (d = 0.98), and eating disorder psychopathology decreased significantly (d = 1.01). Psychosocial impairment and intuitive eating showed non-significant improvements with moderate effects. Dietary intake data were limited by missingness. Qualitative findings highlighted the central role of dietitians, the importance of interprofessional relationships, and areas for refinement. Conclusions: CBT-IE was feasible, highly acceptable, and showed promising clinical outcomes. A fully powered trial is warranted to evaluate efficacy, cost-effectiveness, and implementation across diverse outpatient settings.