Improving Descriptive Diagnostics of Autism in People With Moderate or Severe Intellectual Disabilities: A Qualitative Participatory Study

This study aimed to improve descriptive autism assessment for people with moderate to severe intellectual disabilities (ID) in the Netherlands. The goal was to co-design a framework including an overview of assessment instruments, and recommendations for evaluating broader functioning, for translating findings into daily care and for involving representatives and staff.

We used a participatory design, involving parents/representatives, clinicians, care staff, and management from ID and mental health services. The process included a literature study of autism-related instruments, a Delphi study to reach consensus on suitable instruments, and four focus group discussions (FGDs) exploring stakeholder involvement and the role of assessment instruments in the diagnostic process.

The literature study identified 20 relevant instruments, of which 13 were selected through the Delphi study (n=37, three rounds). Key selection criteria included low burden for individuals, use of multiple information sources, and strong psychometric quality. While quick assessments were preferred, concerns arose about oversimplifying the autism assessment. FGDs (n=5-12) highlighted eight themes on stakeholder involvement, focusing on timing, roles, and goals. Although no consensus emerged on an optimal combination of tools, clarity about an instrument's purpose and implications proved important. The final FGD identified five potentially overlapping phases in the diagnostic process.

The co-designed framework provides an overview of instruments for the assessment of autism and emphasises early and continuous involvement of parents and caregivers. Their participation is essential for defining concerns, guiding assessment goals, sharing information, and applying diagnostic outcomes to improve daily care and support.