Stepping into day treatment approach versus inpatient treatment for adults with anorexia nervosa: the DAISIES RCT.

Background: A substantial proportion of anorexia nervosa patients require intensive treatments, commonly inpatient or day-patient treatment. The relative merits of these treatments for adults with anorexia nervosa are unknown. Therefore, a trial investigating the clinical effectiveness and cost-effectiveness of inpatient treatment-as-usual versus a stepped-care day-patient approach in adults with anorexia nervosa (DAISIES) was commissioned. This trial terminated prematurely due to poor recruitment, mainly resulting from COVID-19's impact on service provision.

Objective: We describe the rationale, methods and available outcomes of the DAISIES trial. Reasons behind the trial's failure and implications for future research are investigated.

Design: A two-arm multicentre open-label parallel-group non-inferiority randomised controlled trial, evaluating the effectiveness, acceptability and cost-effectiveness of two intensive treatments for adults with severe anorexia nervosa.

Setting: Specialist eating-disorder services in the United Kingdom with inpatient and/or day-patient treatment facilities.

Participants: Adults (age 17 +) with severe anorexia nervosa (body mass index ≤ 16 kg/m²) requiring intensive treatment and (optionally) their carers. Intended sample size: 386.

Interventions: Inpatient treatment-as-usual and a stepped-care day-patient treatment approach (with the option of initial inpatient treatment for medical stabilisation).

Main outcome measures: The primary outcome was body mass index at 12 months post randomisation. Qualitative interviews conducted during the trial included semistructured interviews to investigate patients', families' and clinicians' views on treatments.

Results: During the 16-month recruitment period (November 2020 to March 2022), 53 patients were approached. Of these, 15 were enrolled and randomly allocated to the inpatient treatment-as-usual (n = 7) or day-patient treatment (n = 8) treatment arms. All participants were female with a mean (standard deviation) age of 24.8 (9.1) years and a mean (standard deviation) body mass index of 14.4 (1.6) kg/m². Patients' body mass indexes had increased similarly in both groups at 12 months. Participants perceived the stepped-care day-patient treatment approach to be more acceptable than inpatient treatment-as-usual. Qualitative interviews with patients, carers and clinicians suggested valued (e.g. multidisciplinary provision of care) and disliked (e.g. perceived over-focus on weight gain) aspects of treatment. Investigation of the reasons behind the trial's failure revealed strong treatment preferences among patients as the most common reason for non-participation, alongside the impact of COVID-19 on service provision.

Limitations: The main trial questions could not be answered due to low participant numbers.

Conclusions: No conclusions can be drawn concerning the clinical and cost-effectiveness of inpatient treatment-as-usual or stepped-care day-patient treatment. The day-patient treatment approach was perceived more positively by patients and carers. Service-related (e.g. reduced clinician time for research), patient-related (e.g. treatment preferences) and wider systemic factors (e.g. reduced service capacity and patient throughput nationally during COVID-19) seem to have contributed to the failure of the DAISIES trial.

Future work: Despite the trial's failure, the need to investigate the effectiveness and experience of intensive treatments of adult anorexia nervosa remains. Alternative trial designs incorporating patient preferences and investigating community-based intensive treatment options have potential to improve acceptability and recruitment.

Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme as award number HTA 17/123/03.