Psychometric properties of the EQ-5D-Y-5L for children with intellectual disability.

OBJECTIVES: The EQ-5D-Y-5L is a generic preference-based measure of health-related quality of life (HRQoL) for children. This study aimed to describe the distributional properties, test-retest reliability, and convergent validity of the EQ-5D-Y-5L in children with intellectual disability (ID).

METHODS: Caregivers of children with ID (aged 4 to 18 years) completed an online survey including a proxy-report EQ-5D-Y-5L, the Quality of life Inventory-Disability (QI-Disability), and disability-appropriate measures corresponding to the EQ-5D dimensions: mobility (MO), self-care (SC), usual activities (UA), pain/discomfort (PD), and worry/sadness/unhappiness (WSU). Twenty-one participants repeated the EQ-5D-Y-5L a few weeks later. Test-retest reliability was computed using weighted kappa and Intraclass Correlation Coefficients (ICCs), and convergent validity using Spearman's and Pearson's correlation coefficients.

RESULTS: Caregivers of 234 children completed the survey, with <1% missing values. Only 1.7% reported "no problems" on all dimensions (11111). The dimensions with the lowest percentage of "no problems" were SC and UA (both 8%). Test-retest reliability coefficients were fair to substantial for 4 dimensions (weighted kappa .30 to .79) but low for pain and overall health, as measured by the visual analogue scale (EQ-VAS). Convergent validity was strong (Spearman's correlation .65 to .87) for MO, SC, and PD; moderate to strong for WSU (.47 to .60), and the EQ-VAS (Pearson's correlation .49); and weak to moderate for UA (.21 to .52).

CONCLUSIONS: Convergent validity was generally good; test-retest reliability varied. Children with ID had lower scores on SC and UA than other populations and their EQ-VAS could fluctuate greatly, indicating poorer and less stable HRQoL.