Validating the 12-item proxy-administered World Health Organization Disability Assessment Schedule (WHODAS) 2.0 in young children with chronic physical illness in Canada

Purpose This study investigated the psychometric properties of the 12-item proxy-administered World Health Organization Disability Assessment Schedule (WHODAS) 2.0 in young children with chronic physical illness in Canada. Materials and methods Data come from the Multimorbidity in Youth across the Life-course, a longitudinal study of Canadian youth with physical illnesses (n = 263). Baseline parent-reported data from children (2-9 years, n = 143) and adolescents (10-16 years, n = 117) were analyzed. Wilcoxon's tests examined differences in WHODAS 2.0 scores between subgroups. Internal consistency was estimated, and confirmatory factor analysis modeled the WHODAS 2.0 factor structure. Regression modeling examined if the WHODAS 2.0 could discriminate between children with vs. without mental comorbidity. Results Differences were found between children and adolescents regarding self-care and getting along, and for the item on emotional affect. Inter-item correlations were similar between subgroups and internal consistency was strong for children (alpha = 0.90) and adolescents (alpha = 0.93). The factor structure of the WHODAS 2.0 was confirmed; parameter estimates were similar between subgroups. The association between mental comorbidity and disability did not differ by age - comorbidity was associated with greater disability (beta = 5.87, p < 0.01). Conclusions The 12-item proxy-administered WHODAS 2.0 appears valid and reliable in young children with physical illness and can be used in this population.