BackgroundThis case study examines the application of Integrated Enhanced Cognitive Behavioural Therapy (I-CBTE) for a patient with severe, longstanding anorexia nervosa and multiple comorbidities, including organic hallucinosis, complex post-traumatic stress disorder (CPTSD), and severe self-harm. Such complex presentations often result in patients falling between services, which can lead to high chronicity and increased mortality risk. Commentaries from two additional patients who have recovered from severe and longstanding anorexia nervosa are included.Case studyThe patient developed severe anorexia nervosa and hallucinosis after a traumatic brain injury in 2000. Despite numerous hospitalisations and various psychotropic medications in the UK and France, standard treatments were ineffective for 17 years. However, Integrated Enhanced Cognitive Behaviour Therapy (I-CBTE) using a whole-team approach and intensive, personalised psychological treatment alongside nutritional rehabilitation proved effective.MethodsIn this paper, we describe the application of the I-CBTE model for individuals with severe, longstanding, and complex anorexia nervosa, using lived experience perspectives from three patients to inform clinicians. We also outline the methodology for adapting the model to different presentations of the disorder.OutcomesThe patient achieved and maintained full remission from her eating disorder over the last 6 years, highlighting the benefit of the I-CBTE approach in patients with complex, longstanding eating disorder histories. Successful treatment also saved in excess of £360 k just by preventing further hospitalisations and not accounting for the improvement in her quality of life. This suggests that this method can improve outcomes and reduce healthcare costs.ConclusionThis case study, with commentaries from two patients with histories of severe and longstanding anorexia nervosa, provides a detailed description of the practical application of I-CBTE for patients with severe and longstanding eating disorders with complex comorbidities, and extensive treatment histories. This offers hope for patients and a framework for clinicians to enhance existing treatment frameworks, potentially transforming the trajectory of those traditionally deemed treatment resistant.RecommendationsWe advocate the broader integration of CBT for EDs into specialist services across the care pathway to help improve outcomes for patients with complex eating disorders. Systematic training and supervision for multidisciplinary teams in this specialised therapeutic approach is recommended. Future research should investigate the long-term effectiveness of I-CBTE through longitudinal studies. Patient feedback on experiences of integrated models of care such as I-CBTE is also needed. In addition, systematic health economics studies should be conducted.