Disability Stage is an Independent Risk Factor for Mortality in Medicare Beneficiaries Aged 65 Years and Older

BACKGROUND: Stages of activity limitation based on activities of daily living (ADLs) and instrumental activities of daily living (IADLs) have been found to predict mortality in persons aged 70 years and older but have not been examined in Medicare beneficiaries aged 65 years and older using data that are routinely collected. OBJECTIVE: To examine the association between functional stages based on items of ADLs and IADLs with 3-year mortality in Medicare beneficiaries aged 65 years and older, accounting for baseline sociodemographics, health status, smoking, subjective health, and psychological well-being. DESIGN: A cohort study using the Medicare Current Beneficiary Survey (MCBS) and associated health care utilization data. SETTING: Community administered survey. PARTICIPANTS: The study included 9698 Medicare beneficiaries aged 65 years and older who participated in the MCBS in 2005-2007. MAIN OUTCOME MEASURES: Death within 3 years of cohort entry. RESULTS: The overall mortality rate was 3.6 per 100 person years, and 3-year cumulative mortality was 10.3%. Unadjusted 3-year mortality was monotonically associated with both ADL stage and IADL stage. Adjusted 3-year mortality was associated with ADL and IADL stages, except that in some models the hazard ratio for stage III (which includes persons with atypical activity limitation patterns) was numerically lower than that for stage II. CONCLUSION: We found nearly monotonic relationships between ADL and IADL stage and adjusted 3-year mortality. These findings could aid in the development of population health approaches and metrics for evaluating the success of alternative economic, social, or health policies on the longevity of older adults with activity limitations.