Race-ethnicity and determinants of intracranial atherosclerotic cerebral infarction. The Northern Manhattan Stroke Study.

BACKGROUND AND PURPOSE: The aim of this investigation was to determine the importance of race as a determinant of intracranial atherosclerotic stroke in a community-based stroke sample.

METHODS: Residents from northern Manhattan over age 39 years hospitalized for acute ischemic stroke (n = 438, black 35%, Hispanic 46%, white 19%) were prospectively evaluated. Index ischemic strokes were classified as atherosclerotic (17%), lacunar (30%), cardioembolic (21%), cryptogenic (31%), and other (1%). Atherosclerotic infarcts were subdivided into extracranial (9%) and intracranial (8%) atherosclerosis.

RESULTS: The proportion of extracranial atherosclerotic stroke was similar among the three race-ethnic groups, while intracranial atherosclerosis was more frequent in blacks and Hispanics. The unadjusted odds ratio for nonwhites (blacks and Hispanics combined) was 0.8 (confidence interval [CI], 0.4 to 1.8) for extracranial and 7.8 (CI, 1.04 to 57.7) for intracranial atherosclerosis. Patients with intracranial disease were significantly younger and had an increased frequency of hypercholesterolemia and insulin-dependent diabetes compared with those with nonatherosclerotic disease. The odds ratio for the association of nonwhite race-ethnicity and intracranial atherosclerosis was reduced to 5.2 (CI, 0.7 to 40) after controlling for age and to 4.4 (CI, 0.6 to 35) after controlling for age, education, insulin-dependent diabetes, and hypercholesterolemia.

CONCLUSIONS: The greater prevalence of diabetes and hypercholesterolemia among blacks and Hispanics from northern Manhattan accounted for much of the increased frequency of intracranial atherosclerotic stroke. Further control of these risk factors could reduce the frequency of this stroke subtype and minimize the disparities among different race-ethnic groups.