Agreement of the 12-item World Health Organization Disability Assessment Schedule (WHODAS) 2.0 in parents and youth with physical illness living in Canada

Purpose This study modelled the factor structure and tested for measurement invariance between youth and parent reports on the 12-item World Health Organization Disability Assessment Schedule (WHODAS) 2.0; estimated agreement between informants; and, examined moderators of youth-parent discrepancies. Materials and Methods Data come from the baseline wave of the Multimorbidity in Youth across the Life-course study (n = 117). Multiple-group confirmatory factor analysis was used to test for measurement invariance and Wilcoxon signed-rank tests compared informant scores. Intraclass correlation coefficient (ICC) and Bland-Altman limits of agreement plots were used to examine the youth-parent agreement. Results The WHODAS 2.0 demonstrated measurement invariance [chi(2) = 221.8(136), p < 0.01; RMSEA = 0.073 (0.055, 0.091); CFI = 0.962; and, SRMR = 0.078]. Youth typically reported more disability compared to parent proxies, with the exception of item Q5 (emotional). The agreement was low (ICC = 0.08-0.53). Youth sex moderated informant agreement such that more consistent agreement was seen for female youth (beta = 0.54, p < .01) compared to male youth (beta = 0.11, p = .29). Conclusions Youth and their parents interpret the construct of disability, as measured by the 12-item WHODAS 2.0, similarly. Thus, informant differences represent real differences that are not a consequence of error. Low parent-youth agreement reinforces the need for collecting multiple perspectives in the pediatric setting, especially for male youth.