Abstract WP132: Cerebral Amyloid Angiopathy And Risk Of Ischemic And Hemorrhagic Stroke

Introduction: Cerebral amyloid angiopathy (CAA), a condition characterized by beta amyloid deposition in the cerebral vasculature, is a common cause of intracerebral hemorrhage (ICH) in elderly patients. Radiographic features of CAA such as white matter hyperintensities and cerebral microbleeds are also associated with an increased risk of ischemic stroke. However, there are limited population-based data regarding the risk of incident ischemic and hemorrhagic stroke 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. Participants with prevalent stroke were excluded. The primary outcome was any stroke (ischemic or hemorrhagic), and secondary outcomes were ICH, subarachnoid hemorrhage (SAH), and ischemic stroke, assessed separately. These outcomes were identified using validated ICD-10-CM diagnosis codes. Cox proportional hazards regression was used to determine the association between CAA and outcomes after adjustment for demographics and vascular comorbidities. Results: Of the 1.3 million Medicare beneficiaries included, 436 had clinically documented CAA without a prior or concurrent stroke. During a median follow-up of 3.0 years (IQR, 2.3-3.0), incident ischemic stroke occurred in 29,545 patients (2.28%), SAH in 3,340 (0.26%), and ICH in 4,338 (0.34%). In adjusted Cox models, CAA was significantly associated with an increased risk of any stroke (HR, 3.4; 95% CI, 2.5-4.7), ICH (HR, 17.1; 95% CI, 11.1-26.3), and SAH (HR, 6.2; 95% CI, 2.7-13.9). There was a nonsignificant association with ischemic stroke (HR, 1.4; 95% CI, 0.8-2.4). Conclusions: In a nationally representative cohort of Medicare beneficiaries, CAA was associated with a significantly increased risk of future ICH and SAH, but was not significantly associated with an increased risk of future ischemic stroke.