Determinants of black-white differences in the risk of cerebral infarction. The National Health and Nutrition Examination Survey Epidemiologic Follow-up Study

Abstract

Objective: To determine whether blacks in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study remained at increased risk for cerebral infarction after adjusting for stroke risk factors and sociodemographic factors.

Methods: A cohort study involving 8203 whites and 1362 blacks who participated in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. During the 13-year follow-up, 538 and 122 cerebral infarctions occurred in whites and blacks, respectively.

Results: The black-white risk for cerebral infarction varied by age (P = .007 for race-age interaction). Compared with whites of the same age, blacks aged 35 to 44 years were at significantly increased risk for cerebral infarction (relative risk, 2.62; 95% confidence interval, 1.23 to 5.57), while older blacks, those older than 64 years, were not at increased risk (relative risk, 1.14; 95% confidence interval, 0.90 to 1.46). The relative risk for cerebral infarction decreased to 2.07 (95% confidence interval, 0.97 to 4.42) in younger blacks and 0.82 (95% confidence interval, 0.29 to 2.33) in older blacks after adjustment for age, sex, education, history of heart disease, diabetes, systolic blood pressure, treatment for hypertension, Quetelet index, and serum hemoglobin and magnesium levels.

Conclusions: These results indicate that much of the increased risk for cerebral infarction experienced by blacks can be explained by their higher prevalence of stroke risk factors, especially diabetes, hypertension, and lower educational attainment. Younger blacks, however, may still be at increased risk after adjusting for stroke risk factors.