Background: Studies from Asia suggest that the overall proportion of hemorrhagic stroke is much higher compared to other parts of the world. We sought to evaluate the incidence of ischemic and hemorrhagic strokes in Asians living in the U.S. versus U.S. patients of other races and ethnicities.
Methods: We identified all adult patients with acute ischemic or hemorrhagic stroke in the Nationwide Inpatient Sample from 2002-2011, using well-validated International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) diagnosis codes. Our predictor variable was self-reported Asian race. Our primary outcome was the relative proportion of hemorrhagic compared to ischemic strokes. Survey weights were used to account for the sampling methodology. Trend analysis was then performed using the Chi square test for linear association.
Results: We included 4,449,516 patients in the U.S. with stroke, of whom 3,794,438 (85.3%) had ischemic stroke and 655,078 (14.7%) had hemorrhagic stroke. Of these patients, 98,964 (2.2%) were Asian. Amongst the entire sample of stroke patients, Asians had a higher proportion of hemorrhagic strokes compared to the general population (24.0% vs. 14.5%, p<0.001). Asian patients were also more likely to have diabetes mellitus (28.8% vs. 23.7%, p<0.001) and hypertension (82.4% vs. 75.1%, p<0.001) compared to other races and ethnicities. Conversely, atrial fibrillation was less common in Asians (14.8% vs. 19%, p<0.001). There were no significant trends in the relative proportions of stroke types among different races and ethnicities over the past decade.
Conclusions: The incidence of hemorrhagic strokes appears to be higher among Asian compared to patients of other races and ethnicities in the U.S. Further study is warranted to delineate the role of genetic versus environmental factors in explaining the greater propensity to hemorrhagic as opposed to ischemic stroke in Asians.