Black-white differences in stroke incidence in a national sample. The contribution of hypertension and diabetes mellitus.

Although national data have consistently shown an increased risk of death from stroke among blacks, few studies have addressed the reasons for this excess mortality. We compared the incidence of stroke among 1298 blacks and 7814 whites, aged 35 to 74 years, in the 10-year follow-up of the respondents from the First National Health and Nutrition Survey. Blacks had a higher estimated incidence of stroke than whites even after adjustment for age, hypertension, and diabetes mellitus; the relative risk was 1.4 (95% confidence interval, 1.0 to 2.0) for black women and 1.1 (95% confidence interval, 0.8 to 1.6) for black men. The relative risks for stroke associated with hypertension and diabetes mellitus were unrelated to race. Although efforts to treat hypertension and diabetes are among the most important public health measures for reducing stroke, a more complete understanding of the determinants of stroke may be required to account for the excess stroke risk experienced by blacks.