Abstract WP286: Cerebral Amyloid Angiopathy and Risk of Seizures

Abstract

Introduction: Cerebral amyloid angiopathy (CAA) is associated with multiple conditions that are known to have an elevated risk of seizures, including intracerebral hemorrhage, CAA-related inflammation, and Alzheimer’s disease. However, there are limited population-based data regarding the risk of seizures associated with clinically diagnosed CAA. Methods: We performed a retrospective cohort study using inpatient and outpatient claims from 2016 to 2018 from a nationally representative 5% sample of Medicare beneficiaries. The study exposure was a diagnosis of CAA identified using ICD-10-CM code I68.0. The primary outcome was seizure, defined using previously validated ICD-10-CM code G40.x, but excluding diagnosis codes for epileptic conditions that are unlikely to be a result of CAA. Participants with prevalent seizures were excluded. Cox proportional hazards regression was used to determine the association between CAA and seizure after adjustment for age, sex, race, and vascular risk factors. Results: Of 1,403,686 patients included during the study period, 425 (0.03%) were diagnosed with CAA. Median follow-time was 3 years (IQR, 2.4-3). The cumulative incidence rate of seizures was 6.9 (95% CI, 4.8-9.9) per 100 person-years in patients with CAA and 0.30 (95% CI, 0.29-0.30) per 100 person-years in patients without CAA. In Cox proportional hazards analysis, CAA was associated with an increased risk of seizures (HR, 12.6; 95% CI, 8.8-18.0). Conclusions: In a nationally representative cohort of Medicare beneficiaries, CAA was associated with an increased risk of seizures.