Evaluation of an activities of daily living scale for adolescents and adults with developmental disabilities

Abstract

Background: Activity limitations are an important and useful dimension of disability, but there are few validated measures of activity limitations for adolescents and adults with developmental disabilities.

Objective/hypothesis: To describe the development of the Waisman Activities of Daily Living (W-ADL) Scale for adolescents and adults with developmental disabilities, and systematically evaluate its measurement properties according to an established set of criteria.

Methods: The W-ADL was administered among four longitudinally studied groups of adolescents and adults with developmental disabilities: 406 with autism; 147 with fragile-X syndrome; 169 with Down syndrome; and 292 with intellectual disability of other or unknown origin. The W-ADL contains 17 activities and each is rated on a 3-point scale (0 = "does not do at all", 1 = "does with help", 2 = "independent"), and a standard set of criteria were used to evaluate its measurement properties.

Results: Across the disability groups, Cronbach's alphas ranged from 0.88 to 0.94, and a single-factor structure was most parsimonious. The W-ADL was reliable over time, with weighted kappas between 0.92 and 0.93. Criterion and construct validity were supported through substantial associations with the Vineland Screener, need for respite services, caregiving burden, and competitive employment. No floor or ceiling effects were present. There were significant group differences in W-ADL scores by maternally reported level of intellectual disability (mild, moderate, severe, profound).

Conclusions: The W-ADL exceeded the recommended threshold for each quality criterion the authors evaluated. This freely available tool is an efficient measure of activities of daily living for surveys and epidemiological research concerning adolescents and adults with developmental disabilities.

Conflict of interest statement

Conflicts of Interest

None.

Copyright © 2013 Elsevier Inc. All rights reserved.

Figures

Figure 1

Hierarchical cluster (ICLUST) analysis of W-ADL items, path values represent reliability-corrected correlation coefficients, as calculated by ICLUST. Scree plot (inset lower right) showing Eigen values of first N factors and principal components. Both suggest a single-factor structure. Includes all (N=989) participants with complete W-ADL at initial time point.

Figure 2

Scatterplot showing relationship between Vineland Screener adaptive behavior composite score (y-axis) and W-ADL score (x-axis) with loess smoothing line. N=249 adults with autism at Time 4; points slightly jittered to avoid overplotting. Pearson correlation coefficient = 0.78

Figure 3

Boxplot showing W-ADL scores by reported “level” of intellectual disability among 455 adults with Down syndrome and intellectual disability at Time 1. Means and standard deviations for each level shown below figure, showing differentiation between groups.