Incidence and prevalence of dementia among US Medicare beneficiaries between 2015 – 2021
1. In this cohort of older adults, the overall incidence of dementia decreased from 2015 to 2021, however, the prevalence increased.
Evidence Rating Level: 2 (Good)
Dementia has become a top priority in the United States due to the rapidly aging population. Dementia is a group of neurological conditions characterized by a decline in cognitive function that interferes with daily life. The burden of disease disproportionately impacts marginalized communities, specifically Black Americans and those with a lower socioeconomic status. This study aimed to assess how dementia rates vary by sex, race, and neighborhood deprivation using Medicare data, to inform future policies. To best achieve this, a retrospective population-based cohort study was conducted using Medicare claims data from 2013 to 2021 to analyze dementia rates in older adults. Researchers included only those enrolled in traditional fee-for-service Medicare, excluding those with private health plans. The primary outcomes were the rates of dementia incidence and prevalence adjusted for age and sex. Between 2015 to 2021, there were 5,025,039 new cases of dementia reported. The number of cases decreased from 838,824 to 628,902, with age and sex-adjusted incidence rates decreasing from 3.5% to 2.8%. During this same period, prevalence increased, reaching the highest point in 2019 with 3,140,758 cases before slightly declining to 2,875,718 by 2021, corresponding to an increase from 10.5% to 11.8%. In 2015, men had a statistically significantly higher rate of dementia than women (3.5% vs. 3.4%). By 2021, the difference had grown further (2.9% vs. 2.6%; estimated difference-in-difference 0.94, 95% confidence interval (CI) 0.94 to 0.95; P<0.001). In 2015, the highest age- and sex-adjusted incidence rates of dementia were in black beneficiaries (4.2%, 95% CI 4.2% to 4.2%), followed by Hispanic beneficiaries (3.7%, 3.6% to 3.7%), and non-Hispanic white beneficiaries (3.4%, 3.4% to 3.5%). In 2021, black beneficiaries still had the highest incidence (3.1%), followed by non-Hispanic white beneficiaries (2.8%) and then Hispanic beneficiaries (2.6%). The gap in dementia rates between white beneficiaries and other racial and ethnic groups decreased significantly between 2015 and 2021 (estimated difference-in-difference 0.92 (95% CI 0.91 to 0.93) compared with black beneficiaries, 0.88 (0.87 to 0.89) compared with Hispanic beneficiaries). In this retrospective cohort study from 2015 to 2021, the incidence of dementia decreased, however, the prevalence significantly increased, indicating that by 2021, approximately 2.9 Medicare beneficiaries likely had a dementia diagnosis.
Click to read the study in BMJ
Image: PD
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