Detection Rates of Mild Cognitive Impairment in Primary Care for the United States Medicare Population.

Background: Existing evidence points to substantial gaps in detecting mild cognitive impairment in primary care but is based on limited or self-reported data. The recent emergence of disease-modifying treatments for the Alzheimer's disease, the most common etiology of mild cognitive impairment, calls for a systematic assessment of detection rates in primary care.

Objectives: The current study aims to examine detection rates for mild cognitive impairment among primary care clinicians and practices in the United States using Medicare claims and encounter data.

Design: Observational study.

Setting: Medicare administrative data.

Participants: The study sample includes a total of 226,756 primary care clinicians and 54,597 practices that had at least 25 patients aged 65 or older, who were enrolled in Medicare fee-for-service or a Medicare Advantage plan between 2017 and 2019.

Measurements: The detection rate for mild cognitive impairment is assessed as the ratio between the observed diagnosis rate of a clinician or practice as documented in the data, and the expected rate based on a predictive model.

Results: The average detection rates for mild cognitive impairment is 0.08 (interquartile range=0.00-0.02) for both clinicians and practices, suggesting that only about 8% of expected cases were diagnosed on average. Only 0.1% of clinicians and practices had diagnosis rates within the expected range.

Conclusions: Mild cognitive impairment is vastly underdiagnosed, pointing to an urgent need to improve early detection in primary care.