Development and Validation of a Health Measure for Down Syndrome.

Abstract

To develop a caregiver-reported measure to evaluate the overall health of individuals with Down syndrome (DS). After developing and testing a pool of items, a survey was constructed and administered to a large national sample of caregivers of individuals with DS aged 0-21 years from February 2023 to February 2024; pediatricians and teachers were also surveyed. Item distribution and principal components analysis were performed, followed by confirmatory factor analysis. Internal consistency, test-retest reliability, construct validity, and known-group validity were evaluated. The survey was completed by 542 caregivers. Item response and distribution properties were excellent with minimal to no missing data, ceiling, or floor effects. Final confirmatory factor analysis with oblique rotation resulted in 7 scales across 3 domains (25 items) with acceptable to excellent internal consistency (Cronbach's α: 0.7734-0.9587) and moderate to excellent test-retest reliability (intraclass correlation coefficients: 0.711-0.942). The 7 subscale scores and the total score each correlated strongly, as hypothesized, with external measures (P < .001). Known-group validity demonstrated the ability to differentiate individuals with DS and individuals with autism spectrum disorder. A 25-item caregiver Down Syndrome Health Measure consisting of 3 domains and 7 scales demonstrated acceptable psychometric properties. This measure can be utilized to better understand the health needs and improve the management of children and adolescents with DS. ClinicalTrials.gov-NCT04631237.