Measurement invariance of the 12-item self-administered World Health Organization Disability Assessment Schedule (WHODAS) 2.0 across early and late adolescents in Canada

Abstract

Purpose This study examined whether the 12-item self-administered World Health Organization Disability Assessment Schedule (WHODAS) 2.0 demonstrated measurement invariance between young adolescents aged 10–16 years with a physical illness and older adolescents aged 15–19 years from the general population. Materials and methods Young adolescent data come from the baseline wave of the Multimorbidity in Youth across the Life-course study (n = 117) and older adolescent data come from the Canadian Community Health Survey-Mental Health (n = 1851). Multiple-group confirmatory factor analysis was used to test measurement invariance. WHODAS 2.0 scores were compared across morbidity subgroups using multiple regression. Results Measurement invariance of the WHODAS 2.0 was demonstrated: (χ 2=635.2(144), p<.001; RMSEA = 0.059 (0.054, 0.064); CFI = 0.967; TLI = 0.970; and, SRMR = 0.068). Adjusting for data source, sex, race, immigrant status, and household income, WHODAS 2.0 scores were associated with morbidity status in a dose–response manner: physical illness only (B = 1.50, p<.001), mental illness only (B = 2.92, p<.001), and physical–mental comorbidity (B = 4.44, p<.001). Conclusions Measurement invariance of the WHODAS 2.0 suggests that young adolescents interpret the items and disability construct similarly to older adolescents – a group that previously demonstrated measurement invariance with an adult sample. The 12-item self-administered WHODAS 2.0 may be used to measure disability across the life-course. IMPLICATIONS FOR REHABILITATION The 12-item self-administered WHODAS 2.0 is one of the most widely used measures of disability and functioning. Measurement invariance of the WHODAS 2.0 suggests that young adolescents interpret the items and disability construct similarly to older adolescents and adults in Canada. Researchers and health professionals can be confident that differences in 12-item self-administered WHODAS 2.0 scores are real and meaningful. The 12-item self-administered WHODAS 2.0 may be used to measure disability across the life-course.