Psychometric Properties and Informant Agreement of the WHODAS 2.0 in Youth with Mental Disorder and their Parents

Abstract

Background: Mental disorders affect one in five youth and the impact of these disorders extend across the life course. Functional impairment moderates many of the negative effects of mental disorders; however, its assessment can be elusive in the context of child psychiatry. Patient-reported data are integral for clinicians to obtain health information and evaluate the health and functioning of children with mental disorder. While there is value in obtaining health assessments from multiple informants, youth self-report and parent proxy-reports often disagree. This disagreement can be complex to manage and can negatively impact care and health outcomes for youth.

Objectives: This study estimated convergent/divergent validity, internal consistency, parent-youth disagreement, and factors associated with disagreement on the 12-item and 36-item versions of the World Health Organization Disability Assessment Schedule (WHODAS) 2.0, an assessment of functional impairment.

Methods: Data came from a sample of 56 youth aged 14-17 years with a common mental disorder who received either inpatient or outpatient mental health services at tertiary pediatric care center in Ontario, Canada. Correlations between the WHODAS 2.0 and domain scores on the KIDSCREEN-27, a health-related quality of life assessment, were used to assess convergent validity. Correlations between the WHODAS 2.0 and demographic variables (youth age, youth sex, and household income) were used to assess divergent validity. Internal consistency was measured using ordinal . The Bland-Altman method and intraclass correlation coefficients (ICC) were used to assess parent-youth disagreement. Finally, logistic regression models were created to explore factors associated with clinically meaningful disagreement between parents and youth on the 36-item and 12-item version of the WHODAS 2.0.

Results: Correlations between WHODAS 2.0 scores and KIDSCREEN domain scores were low to moderate for both parents (= -0.42 to -0.05) and youth (= -0.41 to 0.01). Correlations between WHODAS 2.0 scores and demographic variables were low to moderate for both parents (/Point Biserial = -0.12 to 0.29) and youth (/Point Biserial = -0.06 to 0.32). All ordinal  values were >0.7. Therefore, internal consistency of both versions of the WHODAS 2.0 was sufficient for both youth and parent raters. Parent reports on the 35-item, 12-item, and domain scores for the WHODAS 2.0 were lower than youth reports. There were significant differences between parent and youth scores for both versions of the WHODAS 2.0 scores, and for the cognition, mobility, and participation domains. Bland-Altman plots revealed measurement error between informants, and agreement was low to moderate (ICC -0.04 to 0.33). Logistic regression analyses revealed that household income <$75,000 was associated with lower odds of meaningful disagreement between parent and youth WHODAS 2.0 scores on the 36-item WHODAS 2.0, and increased youth age was associated with lower odds of meaningful disagreement between parent and youth WHODAS 2.0 scores on the 12-item WHODAS 2.0.

Conclusion: Because conclusions derived from both versions of the WHODAS 2.0 are similar, the 12-item version is sufficient for measuring functional impairment in a clinical context of youth with mental disorder. However, reports from both youth and parents appear valuable in understanding functional impairment. Additional work is needed to understand the factors that influence discrepancies and the implications for care.