A qualitative study exploring the acceptability of taking part in a large multi-centre RCT of medication for anxiety in autistic adults (the STRATA trial)

Background: Autistic adults face significant health and mental health disparities, yet remain underrepresented in clinical research, with few randomised controlled trials (RCTs) to guide care. RCTs of selective serotonin reuptake inhibitors (SSRIs) in this population are limited in number, underpowered, and focused on outcomes other than anxiety. Anticipating recruitment issues in a large RCT (“STRATA”) to determine the clinical and cost effectiveness of the SSRI sertraline in reducing symptoms of anxiety in autistic adults, we embedded qualitative research to support ongoing recruitment and retention and monitor the acceptability of trial procedures in real time. Objectives: To investigate aspects of trial design and delivery that encouraged autistic adults to enrol and remain engaged with STRATA. The Theoretical Framework of Acceptability was applied to assess trial processes acceptability.Methods: 64 qualitative interviews were conducted and thematically analysed with autistic adults at various stages of trial involvement, including 2 who declined trial participation. Results: Overall, most interviewees taking part in STRATA considered trial participation acceptable because most experienced a positive affective attitude towards trial participation, and perceived the study as low burden, ethically sound, and coherent with their understanding of the methodology, as well as representing some low emotional and cognitive trade offs, providing potential benefits for themselves, and reaffirming self-efficacy relating to participation in the trial and managing their anxiety. Discussion: With 318 participants recruited across the UK and Australia, STRATA is one of the largest RCTs conducted with autistic adults with a high retention rate (92% at primary outcome, and 87% at 52 weeks). Our findings demonstrated that conducting trials with and for autistic adults is feasible. Such studies should prioritise creating accessible information and materials, consider individual communication preferences, and have meaningful involvement of autistic people throughout the research cycle, as demonstrated in STRATA, and supported by other research teams.