Assessment of an Expanded Functional Disability Scale for Older Adults With Diabetes

Although prior literature has shown the plausibility of combining the Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) items to form an expanded scale for measuring the degree of functional decline, this has not been shown in older adults with diabetes who are disproportionately affected by functional disability. Using the 2009 Medicare Current Beneficiary Survey data, we evaluated the factor structure of the pooled ADL and IADL items. Based on our study comprising 2,158 community-dwelling older adults (65 years) with diabetes, the unidimensional model exhibited good fit. Despite well-fitting indices, high correlations were observed between the latent constructs (>.70) of the multi-factor models, suggesting a lack of discriminant validity. These findings provide empirical support for a combined scale that can comprehensively and efficiently characterize the extent of functional disability in older adults with diabetes for research, risk adjustment, and evaluation in patient-centered medical homes.