|Title||Assessing patterns and stability of ADL hierarchical scales for functional disability assessment.|
|Publication Type||Journal Article|
|Year of Publication||Forthcoming|
|Authors||Fong, JH, Youn, Y|
|Keywords||ADL index, Epidemiology, functional disability, Psychometrics, Rasch analysis|
BACKGROUND AND OBJECTIVES: This study examined the stability over time of activities of daily living (ADL) items in three comparable longitudinal datasets and evaluated ADL loss sequences for older adults in the U.S., South Korea, and Japan.
RESEARCH DESIGN AND METHODS: Data from the U.S. Health and Retirement Study, and its two international sister surveys, were analyzed. Subjects were community-dwelling adults aged 60 and above. For each dataset, Rasch analysis was implemented to determine if the ordering of items remained stable across multiple waves (2006-2014), such that a single ADL hierarchy may be derived from multi-wave data.
RESULTS: Data fitted the Rasch model well. Item calibrations were sufficiently stable across measurement periods in each dataset, reflecting a stable frame of reference. Results were also robust to sample variations. The derived ADL hierarchies based on scaled logit scores revealed that "dressing" and "bathing" were relatively more difficult items for older adults in all study populations.
DISCUSSION AND IMPLICATIONS: Scale stability is essential when exploiting longitudinal data to analyze patterns in ADL disabilities. The consistency in ADL scales across measurement periods supports their use as screening tools and identifying those at risk for transitions in care. Interventions to reduce dependency in bathing and dressing can help improve independent functioning for community-dwelling elderly.