Treatment adaptations to family-based treatment for children and adolescents with anorexia nervosa or atypical anorexia nervosa, and their evidence-base: a systematic review

Abstract Background This systematic review aimed to identify and describe existing adaptations to outpatient manualised FBT for children and adolescents with anorexia nervosa or atypical anorexia nervosa (AN/AAN), and to examine the degree to which these are informed by factors that may influence treatment non-completion or non-response. Methods A systematic review was conducted according to PRISMA guidelines. Three databases (APA PsycINFO, Embase, and Web of Knowledge) were searched from 2005 to 4th August 2025, supplemented by citation searching. Inclusion criteria were studies in any language examining adaptations to outpatient manualised FBT for AN/AAN, in participants aged 18 years or under. Quality assessment was completed using the Joanna Briggs Institute critical appraisal tools. The review was prospectively registered (PROSPERO CRD420251114023). Results Searches identified 1794 articles, 988 following removal of duplicates. Thirty-one papers were included (25 primary studies and 6 secondary analytic studies; N = 2,332). Twenty-one distinct adaptations were identified, characterised as add-ons to FBT (13 studies), in-model modifications or flexibility (9 studies), and adaptations beyond the FBT manual (6 studies). Eight studies targeted a known factor influencing treatment non-response including high expressed emotion, early treatment non-response, low parental self-efficacy, and older age. Fifteen studies (58%) did not have a comparator group. Three adaptations showed evidence of benefit over standard FBT: a separated treatment model, parent emotion-coaching and flexible or extended treatment duration. Conclusion While some promising adaptations to Family-Based Treatment were identified, the evidence-base remains limited by a predominance of small, uncontrolled studies and a lack of standardised outcome measures. Adequately powered, controlled studies of promising adaptations may guide clinical practice by demonstrating clear benefit over standard FBT, with an aim to improve treatment outcomes for young people with AN/AAN.