Olanzapine for young PEople with aNorexia nervosa (OPEN): A protocol for an open‐label feasibility study

Introduction Antipsychotics are routinely prescribed off‐label for anorexia nervosa (AN) despite limited evidence. This article presents a protocol of a study aiming to assess the feasibility of a future definitive trial on olanzapine in young people with AN. Methods and analysis In an open‐label, one‐armed feasibility study, 55 patients with AN or atypical AN, aged 12–24, receiving outpatient, inpatient or day‐care treatment who are considered for olanzapine treatment will be recruited from NHS sites based in England. Assessments will be conducted at screening, baseline and at 8‐, 16 weeks, 6‐ and 12 months. Primary feasibility parameters will be proportions of patients who agree to take olanzapine and who adhere to treatment and complete study assessments. Qualitative methods will be used to explore acceptability of the intervention and study design. Secondary feasibility parameters will be changes in body mass index, psychopathology, side effects, health‐related quality of life, carer burden and proportion of participants who would enrol in a future randomised controlled trial. The study is funded by the National Institute for Health Research via Health Technology Assessment programme. Discussion Olanzapine for young PEople with aNorexia nervosa will inform a future randomised controlled trial on the efficacy and safety of prescribing olanzapine in young people with AN. Highlights There is a lack of evidence for the use of pharmacological treatment in anorexia nervosa (AN). The Olanzapine for young PEople with aNorexia nervosa study will assess the feasibility of exploring the safety and efficacy of olanzapine in adolescents and young adults with AN. The study will inform a future randomised controlled trial on the efficacy and safety of prescribing olanzapine for AN.