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. 2023 Jul 22;15(1):128.
doi: 10.1186/s13195-023-01272-z.

Expected and diagnosed rates of mild cognitive impairment and dementia in the U.S. Medicare population: observational analysis

Soeren Mattke  1 , Hankyung Jun  2 , Emily Chen  3 , Ying Liu  4 , Andrew Becker  3 , Christopher Wallick  5
Affiliations

Expected and diagnosed rates of mild cognitive impairment and dementia in the U.S. Medicare population: observational analysis

Soeren Mattke et al. Alzheimers Res Ther. .

Abstract

Background: With the emergence of disease-modifying Alzheimer's treatments, timely detection of early-stage disease is more important than ever, as the treatment will not be indicated for later stages. Contemporary population-level data for detection rates of mild cognitive impairment (MCI), the stage at which treatment would ideally start, are lacking, and detection rates for dementia are only available for subsets of the Medicare population. We sought to compare documented diagnosis rates of MCI and dementia in the full Medicare population with expected rates based on a predictive model.

Methods: We performed an observational analysis of Medicare beneficiaries aged 65 and older with a near-continuous enrollment over a 3-year observation window or until death using 100% of the Medicare fee-for-service or Medicare Advantage Plans beneficiaries from 2015 to 2019. Actual diagnoses for MCI and dementia were derived from ICD-10 codes documented in those data. We used the 2000-2016 data of the Health and Retirement Study to develop a prediction model for expected diagnoses for the included population. The ratios between actually diagnosed cases of MCI and dementia over number of cases expected, the observed over expected ratio, reflects the detection rate.

Results: Although detection rates for MCI cases increased from 2015 to 2019 (0.062 to 0.079), the results mean that 7.4 of 8 million (92%) expected MCI cases remained undiagnosed. The detection rate for MCI was 0.039 and 0.048 in Black and Hispanic beneficiaries, respectively, compared with 0.098 in non-Hispanic White beneficiaries. Individuals dually eligible for Medicare and Medicaid had lower estimated detection rates than their Medicare-only counterparts for MCI (0.056 vs 0.085). Dementia was diagnosed more frequently than expected (1.086 to 1.104) from 2015 to 2019, mostly in non-Hispanic White beneficiaries (1.367) compared with 0.696 in Black beneficiaries and 0.758 in Hispanic beneficiaries.

Conclusions: These results highlight the need to increase the overall detection rates of MCI and of dementia particularly in socioeconomically disadvantaged groups.

Keywords: Alzheimer’s disease; Dementia; Epidemiology; Health systems research; Medicare; Mild cognitive impairment.

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Conflict of interest statement

Soeren Mattke serves on the board of directors of Senscio Systems and the scientific advisory board of AiCure, ALZpath, and Boston Millennia Partners. He has received consulting fees from Biogen, C2N Diagnostics, Eisai, Novartis, Novo Nordisk and Genentech/Roche. Christopher Wallick was an employee and shareholder of Genentech, Inc., a member of the Roche Group, at the time the study was conducted. The other authors report no conflicts.

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