Hypertension Carries Higher Stroke Risk in Black Patients

At a given level of blood pressure, the risk of stroke associated with hypertension is higher for black than in white patients, according to a report in JAMA Internal Medicine.

The study included data on nearly 28,000 black and white participants 45 years and older in a population-based follow-up study of stroke risk factors. The study oversampled blacks and residents of the “stroke belt” of the southeastern United States. Proportional hazards models were used to assess differences in stroke risk factors and outcomes for black and white participants in three age groups (less than 65 years, 65 to 74 years, and 75 years and older) and three systolic blood pressure levels (less than 120 mm Hg, 120 to 139 mm Hg, and 140 to 159 mm Hg).

The analysis included 715 incident strokes over 4.5 years of follow-up. Black participants were more likely to be taking antihypertensive drugs. They also had higher rates of diabetes and left ventricular hypertrophy but lower rates of atrial fibrillation, smoking, and heart disease.

Per 10 mm Hg increase in systolic blood pressure, stroke risk increased by 24 percent for black participants versus 8 percent for white participants. This racial disparity was still significant after adjustment for other risk factors. The racial difference was greatest for participants 45 to 64 years. In this age group, the odds ratio for stroke among black participants was 1.38 for those with prehypertension and 2.38 for those with stage 1 hypertension. (For those with normal blood pressure, the racial difference was nonsignificant.)

The results show a greater increase in stroke risk associated with hypertension in black versus white patients, at similar ages and blood pressure levels. The authors note that black patients are more likely to have hypertension and less likely to have it under control, with uncontrolled blood pressure leading to a higher risk of incident stroke. Blood pressure may help to explain the recognized higher risk of stroke among black Americans, particularly during middle age [Howard G, et al. Racial differences in the impact of elevated systolic blood pressure on stroke risk. JAMA Intern Med 2013; 173:46–51].

March 2013 (Vol. 5, Number 3)