Psychometric properties of the operationalized ICF Core Sets for autism and ADHD: item metrics, reliability, and validity.

Abstract

The WHO's International Classification of Functioning, Disability and Health (ICF) provides a biopsychosocial perspective on health-related functioning, highly relevant for conditions like autism and ADHD. Despite the ICF's many benefits, including providing a holistic assessment of individual challenges and resources, its widespread use has been prevented by its complexity, lack of operationalization, and limited specificity for certain diagnoses. To improve usability and implementation of the ICF, diagnosis-specific ICF Core Sets have been developed, revised, operationalized, and integrated on a digital platform. This psychometric study evaluates the self-and proxy-report versions of the Core Set operationalization. This is a cross-sectional study drawing on data collected from individuals diagnosed with autism (<i>n</i> = 54), ADHD (<i>n</i> = 41), autism and ADHD (<i>n</i> = 42), and general population samples (<i>n</i> = 174), as well as 71 paired assessments. Depending on ICF domain, inter-rater reliability and internal consistency was moderate to high. The Core Sets' ability to distinguish between neurodivergent and general population groups, and the functioning profiles within groups, indicate diagnostic and construct validity. Findings add psychometric evidence to previous results on feasibility and further endorse the adequacy of the Core Sets operationalization for use in basic and applied autism and ADHD science.