Cognitive-behavioural therapy (CBT) for outpatients with anorexia nervosa: a systematic review and meta-analysis of clinical effectiveness.

Anorexia nervosa is commonly treated using outpatient cognitive-behavioural therapy (CBT), but its effectiveness needs to be established. This systematic review and meta-analysis (PROSPERO CRD42023484924) assessed outpatient CBT's effectiveness for anorexia nervosa and explored potential moderators (pre-treatment Body Mass Index (BMI), age, illness duration, protocol duration of therapy, dropout). Searches (SCOPUS, PsycINFO, MEDLINE, grey literature) identified 26 studies reporting pre- to post-treatment outcomes for at least one primary measure (weight, eating disorder symptoms). Studies were medium to high quality. Secondary outcome data (depression, anxiety, quality of life) were also extracted. Meta-analyses (26 studies) found medium to large post-treatment effect sizes for weight (g = 0.87; 95% CI 0.67-1.08) and eating disorder symptoms (g = -0.74; 95% CI -0.93 - -0.54), with change starting early and increasing to follow-up. Effect sizes for secondary outcome measures were medium to large. Pre-treatment BMI moderated weight gain. This review was constrained by excluding non-English language papers and the limited number of papers reporting minimum data for inclusion. Overall, results suggest an optimistic picture for patients with anorexia nervosa treated with outpatient CBT. Clinicians can expect good outcomes using CBT, regardless of patients' starting weight, age, or illness duration.