(094) Brain Imaging In United States Veterans Before and After Establishing Criteria for Use of Anti-amyloid Therapy for Treatment of Mild Cognitive Impairment and Alzheimer’s Dementia

Background: In February 2023, the United States Veterans Affairs Healthcare System (VAHS) established criteria for use of newer anti-amyloid therapy for Alzheimer’s dementia (AD).

Objectives: We aimed to study changes in AD clinical practice, specifically brain imaging studies, before and after the VAHS criteria for use were issued.

Methods: A cohort of 667,158 Veterans with MCI and AD was identified based on having at least one ICD code for mild cognitive impairment (MCI) or AD or a documentation of these diagnoses in the clinical progress notes for visits/hospitalizations between October 2009 and September 2019. Both outpatient and inpatient brain imaging (computed tomography [CT], magnetic resonance imaging [MRI], and positron emission tomography [PET]) for these Veterans were counted monthly starting from March 2022 to December 2023. Interrupted time series regression was used to evaluate the effect of the criteria for the use of anti-amyloid therapy on the percentage of scans ordered.

Results: 236,357 Veterans with MCI (35.4%) and 430,801 Veterans with AD (64.6%) were identified. Overall, 16.0% were Black and 74.7% were White; 5.7% were Hispanic and 90.2% were non-Hispanic. The average age at first ICD code or note for MCI/AD was 72 years. The average monthly counts for MRI, CT, and PET procedures were 1316, 3659, and 49, respectively from March 2022 to February 2023 and 1246, 3376, and 46, respectively from March 2023 to December 2023. Over the entire analysis period, the observed monthly rates (the number of brain scans/1000 patients) fluctuated slightly: MRI, 3.58-4.4; CT, 9.95-11.56; PET, 0.09-0.2. Analysis of statistical trends did not find significant differences in the monthly rates of MRI, CT, or PET scans over time.

Conclusions: This study did not find an increasing trend of brain imaging among patients with MCI and AD following the VAHS issuance of criteria for use of anti-amyloid therapy. We hypothesize that resources for brain imaging may traditionally have been prioritized for cardiovascular, oncological, or therapeutic usage other than AD. The relatively stable trends in usage of brain MRI, CT, and PET procedures before and after the VAHS criteria for use issuance in February 2023, may also suggest a potential capacity limitation of brain imaging resources that can be allocated for MCI/AD diagnosis and monitoring.