TrendsinUSOlderAdultDisability:ExploringAge,Period, andCohortEffects

Objectives. We elucidated how US late-life disability prevalence has changed over the past 3 decades. Methods. We examined activities of daily living (ADL) and instrumental activities of daily living (IADL) disability trends by using age–period–cohort (APC) models among older adults aged 70 years or older who responded to the National Health Interview Survey between 1982 and 2009. We fitted logistic regressions for ADL and IADL disabilities and for each of the 3 APC trends with 2 models: unadjusted and fully adjusted for age, period, cohort, and sociodemographic variables. Results. The unadjusted and adjusted period trends showed a substantial decline in IADL disability, and ADL disability remained stable across time. Unadjusted cohort trends for both outcomes also showed continual declines across successive cohorts; however, increasing cohort trends were evident in the adjusted models. Conclusions. More recent cohorts of US older adults are becoming more disabled, net of aging and period effects. The net upward cohort trends in ADL and IADL disabilities remain unexplained. Further studies should explore cohortspecific determinants contributing to the increase of cohort-based disability among US older adults. (Am J Public Health. 2012;102:2157–2163. doi:10.2105/ AJPH.2011.300602)