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

Abstract

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 (α = 0.90) and adolescents (α = 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 (β = 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.Implications for rehabilitationThe 12-item proxy-administered WHODAS 2.0 has acceptable inter-item correlations and internal consistency in young Canadian children with chronic physical illness, and its factor structure is consistent with previous reportsExpansion of its use in measuring disability in young children provides the opportunity to use the WHODAS 2.0 across the life-course, facilitating the interpretation of changes in disability over time or in response to treatmentAdditional research is needed to determine responsiveness to change and the minimal clinically important difference of the WHODAS 2.0 in this population.

Keywords: Adolescent; chronic disease; disability; functioning; measurement; scales; validity.