Abstract 2733: The Comparative Importance of `Shared' Risk Factors for Ischemic Stroke and Intracerebral Hemorrhage in Patients with Atrial Fibrillation

Abstract

Background: Optimal prescribing of oral anticoagulants, for the prevention of stroke in patients with atrial fibrillation, requires clinicians to estimate the competing risk of ischemic stroke and intracerebral hemorrhage (ICH). However, a number of risk factors increase the risk of both ischemic stroke and ICH (e.g. age, hypertension and chronic renal disease), and it is unclear how these ‘shared’ risk factors should influence decisions on antithrombotic therapy. Objective: To determine the comparative importance of risk factors for ischemic stroke and ICH in patients with atrial fibrillation, focusing primarily on risk factors included in the CHA2DS2VASC (risk of ischemic stroke) and HAS-BLED (risk of major bleeding) scores. Methods: Prospective registry of 3,197 patients admitted with acute ischemic stroke or ICH and atrial fibrillation included in the Registry of the Canadian Stroke Network (Jul 03-Mar 08; 11 Regional Stroke Centers in Ontario, Canada). Multivariable analysis was used to determine the association between baseline risk factors (age, sex, history of hypertension, previous stroke or transient ischemic attack, history of congestive heart failure, history of vascular disease, hepatic impairment, current alcohol intake, history of diabetes mellitus, history of gastro-intestinal bleeding, renal impairment, admission INR and antiplatelet therapy) and risk of ischemic stroke versus ICH. Results: Of 3,197 patients with atrial fibrillation and acute stroke, 2,806 (87.8%) presented with an ischemic stroke and 391 (12.2%) presented with an ICH. Of the ‘shared’ risk factors, age (OR 1.17; 95% CI 1.04-1.31 per decade) and previous history of stroke (OR 1.40; 95% CI 1.09-1.81) were associated with an increased risk of ischemic stroke relative to ICH, while a history of hypertension (OR 0.90; 95% CI 0.69-1.18) and renal impairment (OR 1.29; 0.96-1.72) were not associated with either stroke subtype, on multivariable analyses. Of the ‘non-shared’ risk factors, alcohol consumption of <2 units/day vs. no consumption (OR 1.61; 95% CI 1.24-2.09), female sex (OR 1.53; 95% CI 1.20-1.96) and a history of vascular disease (OR 1.73; 95% CI 1.30- 2.30) were associated with an increased risk of ischemic stroke relative to ICH. Elevated INR at the time of admission was a significant predictor of ICH, relative to ischemic stroke. Conclusion: None of the ‘shared’ risk factors were stronger predictors of ICH compared to ischemic stroke, which has obvious implications for clinical practice. In particular, older age was more strongly associated with ischemic stroke than ICH in patients with atrial fibrillation, and therefore, should be considered as a factor favoring a decision to commence anticoagulant therapy.