Abstract WP108: Risk of Seizures Among Patients with Cerebral Amyloid Angiopathy – a Nationwide Retrospective Cohort Study in the United States

Introduction: Cerebral amyloid angiopathy (CAA) is a progressive cerebrovascular disease caused by amyloid-beta (Aβ) deposition in cerebral vasculature. While CAA is a recognized cause of intracerebral hemorrhage (ICH) and cognitive decline, emerging evidence suggests that seizures are among a broader array of CAA clinical manifestations. However, the risk of seizures and status epilepticus in CAA remains poorly characterized. This study aimed to estimate incidence of seizures and status epilepticus in CAA using real-world data. Methods: A retrospective, longitudinal study was conducted using a nationally representative sample of administrative claims from US Medicare and commercial insurance beneficiaries (2017–2024). Patients with CAA (aged > 50 years with > 1 physician encounter with a validated ICD-10 code (I68.0)) were matched 1:4 to age- and sex-matched controls. The primary outcome was occurrence of seizure, ascertained using validated ICD-10 codes during acute care; the secondary outcome was hospitalization for status epilepticus. Follow-up continued until the end of enrollment or death. Descriptive statistics summarized patient characteristics and Poisson regression estimated incidence rates with 95% CIs. Cox proportional hazards regression assessed associations between CAA and outcomes of interest vs controls, adjusted for chronic kidney disease, liver disease, prior ICH, and seizure history. Results: We included 7294 patients with CAA and 29176 controls (median age: 77 years; 53.7% women; median follow-up: 29.4 months). Patients with CAA had higher rates of prior ICH (32.4% vs 0.5%) and prior seizure (18.7% vs 1.8%) than controls. The incidence rate of seizures was higher in patients with CAA than controls: 8.1 per 100 person-years (PY; 95% CI: 7.6–8.6) vs 0.4 per 100 PY (95% CI: 0.4–0.5). In the CAA cohort, seizure incidence rate was higher for those with prior ICH than those with no ICH history: 13.6 per 100 PY (95% CI: 12.5–14.8) vs 5.7 per 100 PY (95% CI: 5.2–6.3). Status epilepticus rates were higher in patients with CAA than controls: 0.7 per 100 PY (95% CI: 0.6–0.9) vs 0.03 per 100 PY (95% CI: 0.02–0.04). Adjusted models showed that CAA was associated with higher risk of seizures (HR: 6.7, 95% CI: 5.8–7.7) and status epilepticus (HR: 8.1, 95% CI: 4.8–13.7) than controls (Table 1). Conclusions: Patients with CAA have an increased risk of seizures and status epilepticus. These findings broaden the possible clinical spectrum of CAA.