Which risk factors are more associated with ischemic stroke than intracerebral hemorrhage in patients with atrial fibrillation?

BACKGROUND AND PURPOSE The decision to prescribe oral anticoagulant therapy in patients with atrial fibrillation is based on an assessment of the competing risks of ischemic stroke and major bleeding, of which intracerebral hemorrhage (ICH) is the most important type. We sought to determine the comparative importance of risk factors for ischemic stroke and ICH in patients with acute stroke and atrial fibrillation with particular emphasis on risk factors common to both stroke types. METHODS Consecutive patients with acute ischemic stroke or ICH and atrial fibrillation included in the Registry of the Canadian Stroke Network constituted the cohort. Multivariable logistic regression analysis was used to determine the association between baseline risk factors and presentation with ICH versus ischemic stroke. Risk factors included: (1) those previously reported to be risk factors for both ischemic stroke and major bleeding (particularly ICH) ("shared" risk factors, including age, alcohol, hypertension, diabetes mellitus, renal impairment, prior stroke/transient ischemic attack and preadmission dementia); and (2) other risk factors associated with either stroke subtype alone. RESULTS A total of 3197 patients presented with atrial fibrillation and acute stroke, of which 12.2% presented with ICH. Of the "shared" risk factors, age (OR, 1.19; 95% CI, 1.06-1.34 per decade) and prior stroke/transient ischemic attack (OR, 1.45; 95% CI, 1.12-1.87) were more associated with ischemic stroke than ICH, whereas a history of hypertension (OR, 0.89; 95% CI, 0.68-1.17), diabetes mellitus (OR 1.23; 95% CI, 0.92-1.64), renal impairment (OR, 1.28; 95% CI, 0.95-1.71), and alcohol intake were not more strongly associated with either stroke subtype. CONCLUSION Of the risk factors known to be associated with both ischemic stroke and ICH in patients with atrial fibrillation, we found that none had a stronger association with ICH. Older age was more strongly associated with ischemic stroke than ICH.