National trends in the prevalence of dementia in Medicare Advantage and Traditional Medicare.

BACKGROUND: Little is known about how the prevalence of dementia in Medicare Advantage (MA) and traditional Medicare (TM) has changed over time. We examine prevalence of dementia in MA and TM overall and by race/ethnicity, the characteristics of these individuals within plans, as well as enrollment and switching rates between MA and TM between 2000 and 2014. METHODS: Repeated cross-sectional study using eight waves from the Health and Retirement Study (HRS) linked to Medicare enrollment data. Sample includes HRS respondents ≥ 65 years of age (n = 18,381) linked to Medicare enrollment data. Measurements used include predicted cognitive function (Langa-Weir classification: dementia, cognitive impairment not dementia, and normal), three race/ethnicity categories (White, Black, and Hispanic), demographic and clinical characteristics from HRS, and Medicare enrollment (MA or TM) per year. RESULTS: Among TM enrollees, prevalence of dementia was lower by 4% points in 2014 (9.0%, 95%CI: 7.8%, 9.3%) compared to 2000 (13.0%, 95%CI: 12%, 14%). The prevalence of dementia in MA was higher by 2% points in 2014 (10.0%, 95%CI: 8.5%, 11%) compared to 2000 (8.0%, 95% CI: 7.2%, 9.7%). Prevalence of dementia in MA remained stable for Whites non-Hispanic, was 2% points higher for Blacks non-Hispanic, and 5% points higher for Hispanics in 2014 compared to 2000. MA compared to TM beneficiaries with dementia in 2014 were younger (mean [SE] 81.6 [0.5] vs. 83.5 [0.4]), had fewer activity of daily living limitations (1.9 [0.1] vs. 2.4 [0.1]), instrumental activities of daily living limitations (2.3 [0.1] vs. 2.8 [0.1]), and of chronic conditions (3.2 [0.1] vs. 3.5 [0.1]). By 1-year (2012–2013), 6.3% of MA beneficiaries with dementia switched to TM and 4.3% of TM beneficiaries with dementia switched to MA. CONCLUSIONS: Between 2000 and 2014, dementia prevalence was lower in TM compared to MA. Evidence suggests that MA beneficiaries with dementia are younger and have fewer functional limitations than their dementia TM counterparts.