Research Information System
Health technology assessment (Winchester, England), vol.30, no.36, pp.1-17, 2026 (SCI-Expanded, Scopus)
Background: In clinical practice, olanzapine is commonly used in young people with anorexia nervosa, although the underpinning evidence-base is limited. However, its efficacy, tolerability, acceptability and adherence rate, and the patients', carers' and clinicians' views of olanzapine treatment are unclear. This synopsis article summarises the methods and results of the OPEN feasibility study, overarching the findings and drawing comprehensive conclusions from a quantitative feasibility outcome paper and two qualitative research papers. Methods: The OPEN study assessed the feasibility of a future randomised controlled trial on olanzapine in young people with anorexia nervosa in an open-label, one-armed feasibility study. In this study, we aimed to include 55 patients with anorexia nervosa or atypical anorexia nervosa aged 12-24 who gained < 2 kg within at least 1 month of treatment as usual. Time points for assessments were at baseline, 8 weeks, 16 weeks, and 6 or 12 months. We estimated recruitment, adherence and attrition rates and mean changes in body weight, body mass index and eating disorder psychopathology. In addition, we explored the views on and experiences with olanzapine treatment within a clinical trial setting using qualitative interviews with young people with anorexia nervosa, their families and clinicians. Results: Fifty-two people were pre-screened, 35 were eligible and 20 participants were recruited and started olanzapine. Of these, 15 continued olanzapine for ≥ 16 weeks. Participants experienced, on average, a decrease in their eating disorder psychopathology, and body weight and body mass index increased during treatment with olanzapine as an adjunct to treatment as usual. Important themes derived from semi-structured qualitative interviews with young people and their parents were: moving away from the illness towards recovery, evaluating information on olanzapine, consent and trust in shared decision-making and the ambivalence around recovery. The main themes expressed by clinicians included: acknowledging the concerns of young people with anorexia nervosa and their families, prioritising person-centred care, the limited service capacity and strict study eligibility criteria. Limitations: The study failed to meet the recruitment target and showed low adherence rates for treatment with olanzapine. Possible reasons for the recruitment difficulties and the low adherence rate include the high clinical workload of eating disorder services during and after the COVID-19 pandemic, the heterogeneity of eating disorder service setup across the country, and the reluctance of patients to agree to take olanzapine under the relatively restricted conditions of a clinical study. Conclusions: A realistic time schedule for site-preparation, recruitment, treatment and follow-up, realistic recruitment targets and easy access to medical and laboratory examinations may improve the success of future feasibility studies and randomised controlled trials in this patient group. Future work: The difficulties in conducting the OPEN study will inform the planning for future pharmacological and non-pharmacological studies in anorexia nervosa. Therefore, we developed a checklist with action points for the planning of pharmacological trials in eating disorders. Furthermore, novel pharmacological options such as typical and atypical psychedelic drugs (e.g. psilocybin and ketamine) might be more acceptable for people with anorexia nervosa as they do not have the side effect of immediate weight gain. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number NIHR130780. Better treatments are needed for severely underweight young people (age 12–24) with anorexia who do not respond to the standard psychotherapies to support their physical and psychological recovery. Many doctors prescribe olanzapine, because olanzapine has been reported to help with weight gain. However, it has not been approved for treating anorexia yet, because it is unclear whether it is helpful and whether it is safe to be used for young people. Before this study, we did not know what proportion of young people with anorexia would consider olanzapine in addition to usual treatment or participate in a study assessing this. We also wanted to know how long patients might be willing to take it. We had hoped to include 55 patients with anorexia aged 12–24 years into a study testing olanzapine. We documented how many patients agreed to participate and receive olanzapine alongside their usual treatment. For adolescent patients, their parents or guardians also needed to consent. We used questionnaires, physical examinations and laboratory investigations. We examined patients before they started olanzapine, after 8 and 16 weeks, and after 6 and 12 months. However, we were only able to identify 52 potential patients for study. Of these, 35 would have been suitable, but only 20 participants chose to start olanzapine. Of these, 15 continued olanzapine for 16 weeks or longer. Participants experienced, on average, a beneficial effect on their psychological symptoms and some weight gain. Patients and their parents expressed the importance of moving away from the illness and towards recovery, getting accurate in-depth information about olanzapine, and being actively involved in treatment decisions. Clinicians highlighted the importance of acknowledging the concerns of young people with anorexia and their families and providing person-centred care. Staff shortages and other challenges for eating disorder services during and after the COVID-19 pandemic and the strict criteria for entering the study may have been the main reasons for why we were unable to recruit 55 patients with anorexia into this study.