Diagnosis patterns among diverse populations with mild cognitive impairment and Alzheimer’s disease in the USA

Background: Rapid advancements in diagnostic biomarkers and criteria have created a complex and evolving environment for clinicians managing patients with cognitive complaints. Real-world data on current diagnostic processes used among diverse populations remains limited. Objectives: This study aimed to investigate diagnostic patterns and use of diagnostic tests among U.S. adults with mild cognitive impairment, Alzheimer's disease, and/or dementia, stratified by gender, age, and race/ethnicity before clinical availability of blood-based biomarkers and the most recent diagnostic updates. Design: Retrospective, observational cohort study. Setting: The Optum® Market Clarity database from January 1, 2017, to September 30, 2021, was utilized. Participants: 338,739 patients diagnosed with dementia, 81,267 with AD, and 179,419 with MCI were included in the analysis. Measurements: Demographics information identified from electronic health records at the time of diagnosis was utilized. Occurrence and timing of diagnostic tests was pulled from insurance claims and electronic health records. Results: Mean age at diagnosis was 69.3 years for MCI, 78.9 years for AD, and 78.6 years for dementia. Computerized tomography (CT) and magnetic resonance imaging (MRI) were used infrequently (MCI: MRI 16.6%, CT 17.5%; AD: MRI 9.0%, CT 18.4%; dementia: MRI 9.5%, CT 25.9%). Cerebrospinal fluid (CSF) biomarker tests and positron emission tomography (PET) were rarely used (MCI: PET 0.6%, CSF 1.6%; AD: PET 0.5%, CSF 0.9%; dementia: PET 0.2%, CSF 1.6%). Conclusions: During the study period, diagnosis of MCI, AD, and dementia involved low use of brain imaging or CSF biomarkers, despite recommendations from guidelines. By better understanding how patients navigate their diagnostic journey in real-world settings, diagnostic practices can improve and faster support can be provided.