The risk of community-dwelling older adults becoming disabled: application of Cox hazard model with age as time unit

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  • March 21, 2019
Creator
  • Yeo, Yeong Hun
    • Affiliation: School of Social Work
Abstract
  • As the population of older adults increases, disability among older adults is becoming a critical issue for the disabled themselves and society as a whole. The traditional medical perspective views disability as a direct consequence of injury or disease, and disability among the elderly is regarded as an inevitable result of aging. However, the disablement process model posits that disability is not only the product of medical conditions, but rather the result of interactions between medical conditions and various intra- and extra-individual factors. Based on the disablement process model, this dissertation study investigated the black/white disability gap among adults ages 50 and over by investigating risk of disability as defined by difficulty with specific activities of daily living (ADLs) and instrumental activities of daily living (IADLs). Research questions were: 1) Is there a difference between blacks and whites in the risk of disability onset, and does it change with advancing age? 2) If so, to what extent do chronic disease, health behaviors, and socioeconomic status (SES) contribute to that gap? Longitudinal data from a nationally representative sample (N=13,429) were analyzed to track disability onset. Separate analyses were conducted for each of 12 indicators of ADL/IADL disability. To examine the disability gap and how it changes with age, Kaplan-Meier estimates were used to describe disability onset by obtaining survivor/hazard plots. To examine the mediating role of disease, health behaviors, and SES, a series of Cox hazard models with age as time unit were utilized. SES was found to be the largest contributing factor in the black/white disability gap. On average, controlling for SES decreased the gap by 67.7%. When disease, health behaviors, and SES were all controlled for, the gap was narrowed even further. Controlling for these factors also removed the disability crossover phenomenon for most ADL/IADL indicators. This study contributes to the literature by providing a more comprehensive understanding of the disability gap by investigating each indicator of ADL/IADL disability separately, including adults as young as 50 in the sample, and utilizing advanced statistical tools to analyze 11 years of longitudinal data.
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  • In Copyright
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  • "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Social Work."
Advisor
  • Rounds, Kathleen
Degree granting institution
  • University of North Carolina at Chapel Hill
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Place of publication
  • Chapel Hill, NC
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  • Open access
Date uploaded
  • March 18, 2013

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