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

Soeren Mattke; Hankyung Jun; Emily Chen; Ying Liu; Andrew Becker; Christopher Wallick

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

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

Authors

Soeren Mattke¹, Hankyung Jun², Emily Chen³, Ying Liu⁴, Andrew Becker³, Christopher Wallick⁵

Affiliations

¹ Center for Improving Chronic Illness Care, USC Dornsife, University of Southern California, 635 Downey Way, #505N, Los Angeles, CA, 90089, USA. mattke@usc.edu.
² Department of Health Care Policy, Harvard Medical School, Boston, MA, USA.
³ Center for Improving Chronic Illness Care, USC Dornsife, University of Southern California, 635 Downey Way, #505N, Los Angeles, CA, 90089, USA.
⁴ Center for Economic and Social Research, University of Southern California, Los Angeles, CA, USA.
⁵ US Medical Affairs, Genentech, Inc., Roche Group, South San Francisco, CA, USA.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Alzheimer Disease* / diagnosis
Cognitive Dysfunction* / diagnosis
Cognitive Dysfunction* / epidemiology
Humans
Medicare
United States / epidemiology