Racial differences in the effect of high blood pressure on the risk of stroke

This study looks at stroke risk among black Americans and white Americans, and compares groups by age and by matching systolic blood pressures. 

Stroke (a sudden brain dysfunction caused by an interrupted blood supply) is a major cause of death and disability. High blood pressure (hypertension, or HTN), is a known risk factor for stroke. More accurately, the systolic blood pressure (SBP) – the higher value in a blood pressure reading – is the determining factor. The higher the SBP, the higher the risk of stroke. HTN is defined as a blood pressure higher than 140/90 mmHg. It is staged based on severity: stage 1 HTN is defined by the range of 140-159 over 90-99 mmHg.

Studies have shown that the prevalence of HTN is increased among black, compared to white, Americans. In addition, black Americans more frequently have poorly controlled HTN. Taken together, these findings suggest that there may be racial differences in the incidence of stroke among ethnic groups. The present study questioned this hypothesis. 

This study included 27,748 black and white Americans, recruited between 2003-2007, age 45 and older. Each person was interviewed and and followed for 4.5 years; blood pressure and risk factors were documented. During that time, 715 strokes happened among the study population. For each 10 mmHg increase in SBP, the stroke risk for black Americans was triple that of the risk for white Americans (24% increase versus 8% increase). In the age range of 45-65 years, having stage 1 hypertension, black Americans had more than twice (2.38) the rate of stroke compared to white Americans with the same blood pressure. This seems to indicate that HTN is more dangerous for black Americans than for white Americans in regards to stroke risk.

Black Americans are at increased risk of stroke, compared to the white population, due to hypertension. The risk becomes substantially higher among patients 45-65 years old with stage 1 HTN. 

If you are aware of having high blood pressure, discuss with your doctor your treatment options, and self-monitor the blood pressure to make sure that it is under control.