Behavioural interventions to treat anxiety in adults with autism and moderate to severe intellectual disabilities: the BEAMS-ID feasibility study.

Background: Interventions for anxiety need to be adapted to meet the needs of autistic people with moderate to severe learning disabilities and successfully modelled before evidence about efficacy can be generated from clinical trials. Objectives: The objectives were to: (1) adapt a behavioural intervention for anxiety, develop an intervention fidelity checklist and logic model, and appraise candidate outcome measures, together with carers, autistic people, and clinicians, (2) characterise treatment-as-usual, (3) model the adapted intervention to determine the acceptability and feasibility for all stakeholders, judge the appropriateness of outcome measures, examine the feasibility and acceptability of consent and associated processes and (4) describe factors that facilitate or challenge intervention delivery. Design: This study had two phases. Phase 1a: using consensus methods, an intervention adaptation group was formed who met to adapt the intervention, appraise candidate outcome measures, and contribute to the development of the intervention fidelity checklists and logic model. Phase 1b: a national online survey was conducted with professionals to characterise treatment-as-usual. Phase 2: this was a single-group non-randomised feasibility study designed to model the intervention to test intervention feasibility and acceptability, outcome measures, and aspects of the research process. Setting: Participants were recruited from National Health Service community adult learning disabilities teams in England. Participants: Participants aged 16 and over with a diagnosis of autism, moderate to severe learning disabilities, an anxiety disorder, and a carer who was available to take part in the intervention. For those who lacked capacity to make a decision about taking part, a consultee had to provide advice that the participant should be included in the study. Interventions: The intervention comprised 12 sessions alongside treatment-as-usual. Main outcome measures: The feasibility and acceptability of the intervention and research processes, outcome measure completion rates, and intervention adherence. Results: The intervention was successfully adapted and modelled with 28 autistic participants with moderate to severe learning disabilities. The intervention was judged to be feasible and acceptable by autistic adults with learning disabilities, carers, and therapists. Carers and therapists suggested minor intervention revisions. Carers completed 100% of outcome measures and the missing data rate was low; however, they indicated that some of the questions were repetitive and said they had difficulty responding to some items. The use of the Mental Capacity Act, 2005, led to an average 5-week delay to participant enrolment. The accrual rate was affected by the COVID-19 pandemic and improved during the summer and early autumn of 2022. Limitations: Randomisation was not modelled within this feasibility study, although carers and therapists indicated that this would be acceptable. Conclusions: The BEAMS-ID intervention and associated study processes were judged to be feasible and acceptable. The intervention required minor revision. Future work: The BEAMS-ID intervention should be tested further within a trial. Study registration: This study is registered as ISRCTN12637590. Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR129804) and is published in full in