Abstract 164: Cerebral Amyloid Angiopathy Is Associated With A Higher Risk Of Subdural Hemorrhage: Combined Analysis Of The Uk Biobank And All Of Us

Abstract

Background: Cerebral amyloid angiopathy (CAA) is a condition characterized by amyloid deposition in the brain’s blood vessels. CAA is a common cause of spontaneous intracerebral hemorrhage (ICH) in older patients. Although other types of intracranial hemorrhages can occur in conjunction with CAA-related ICH, it is unknown whether CAA is a risk factor for other types of intracranial hemorrhage in the absence of ICH. Hypothesis: CAA is an independent risk factor for isolated non-traumatic subdural hemorrhage (SDH). Methods: We conducted a 2-stage (discovery and replication) observational study that retrospectively analyzed data from the UK Biobank (discovery phase) and the All of Us (replication phase) study. We included participants over 55 years of age to meet the age threshold for the modified Boston Criteria. The exposure was a diagnosis of CAA and the outcome was non-traumatic SDH, both identified using ICD-9 and ICD-10 codes. We used survival analyses with log-rank tests and multivariable Cox proportional hazards models adjusted for demographic characteristics and vascular risk factors. Results: The discovery phase included 283,452 UK Biobank participants comprising 123 CAA cases and 504 SDH cases. SDH subsequently occurred in 2.4% of participants with CAA versus 0.2% of those without CAA. In a multivariable Cox model, CAA was associated with a significantly increased risk of SDH (hazard ratio [HR], 7.3; 95% CI, 2.3-22.7). This finding was replicated among 168,370 study participants in All of US, where 66 had CAA and 443 had a SDH (HR, 11.66; 95% CI, 5.2-26.2). Conclusion: In two large heterogeneous cohorts conducted in different countries, CAA was independently associated with a higher risk of isolated non-traumatic SDH. Further research is needed to further determine causality and identify biological pathways that may mediate this association.