Effectiveness and Cost-effectiveness of Guided Self-help for Depression for Autistic Adults: the Autism Depression Trial (ADEPT-2) - Protocol for a Multicentre, Randomised Controlled Trial of a Remotely Delivered Low-intensity Intervention

Introduction: Depression is three to four times more prevalent in autistic people and is related to reduced quality of life. There is a need for empirically supported psychological interventions for depression specifically adapted to meet the needs of autistic adults. ADEPT-2 aims to establish the clinical and cost-effectiveness of an adapted low-intensity psychological intervention (guided self-help) for depression in autistic adults.

Methods And Analysis: A two parallel-group multicentre pragmatic randomised controlled trial investigating the effectiveness of GSH for depression in autistic adults. Participants (n=248) aged ≥18 years with a clinical diagnosis of autism currently experiencing depression will be randomised to GSH or treatment as usual (TAU). GSH is a low-intensity psychological intervention based on the principles of behavioural activation adapted for autism. GSH comprises informational materials for nine individual sessions facilitated online by a GSH coach who has received training and supervision in delivering the intervention. The primary outcome will be Beck Depression Inventory-II depression scores at 16 weeks post randomisation with follow-up measures at 32 and 52 weeks. Additional measures of anxiety, patient-rated global improvement, quality of life, work and social adjustment, positive and negative affect will be measured 16 and 52 weeks post randomisation. The primary health economic analysis will assess the cost-effectiveness of GSH compared with TAU over 52 weeks, from a societal perspective including the National Health Service, personal social services, personal expenses, voluntary services and productivity. An embedded qualitative study will explore the acceptability, experiences and adherence of participants and therapists to treatment principles.

Ethics And Dissemination: This trial has been approved by the East of England - Essex Research Ethics Committee on 10 June 2022 (REC Reference number: 22/EE/0091). The findings of the research will be submitted for publication in peer-reviewed journals and disseminated in an appropriate format to trial participants and the wider public.

Trial Registration Number: ISRCTN17547011.