The prevalence of diagnosed Alzheimer disease and related dementias (ADRD) is lower in Medicare Advantage health insurance plans than in traditional fee-for-service Medicare, according to a new analysis of data from the NIH Collaboratory Distributed Research Network (DRN). The study was published this month in Alzheimer’s & Dementia.

Much of the current understanding about the characteristics and experiences of people diagnosed with ADRD comes from studies of fee-for-service Medicare beneficiaries. These studies typically do not include the one-third of Medicare beneficiaries who are enrolled in Medicare Advantage plans.

In the new analysis, Jutkowitz and colleagues used data from 3 large health insurance providers that make up 30% of the Medicare Advantage health insurance market. The 3 providers are data partners in the NIH Collaboratory DRN. The researchers found that the age- and sex-stratified prevalence of ADRD among Medicare Advantage beneficiaries was lower than among fee-for-service beneficiaries. They also observed higher disenrollment rates among Medicare Advantage beneficiaries—up to 30% at 1 year—than were found in previous studies. The findings have methodological implications for research in both Medicare Advantage and fee-for-service Medicare populations.

This work was supported within the NIH Collaboratory by the NIH Common Fund through a cooperative agreement from the Office of Strategic Coordination within the Office of the NIH Director and through the NIA IMPACT Collaboratory by the National Institute on Aging. Supplemental funding was provided by the National Center for Complementary and Integrative Health. Learn more about the NIH Collaboratory DRN.