African American men who live in the south are at significantly higher risk of dying from stroke

Feb 3 2005

African American men who live in southern states are at significantly higher risk of dying from stroke than African American men living elsewhere, researchers reported at the American Stroke Association's International Stroke Conference 2005.

Scientists already know that blacks' risk of death from stroke is greater than whites'. Studies also have shown that people who live in the southeastern states that comprise the "stroke belt" are more likely to die from stroke.

This study found that the combination of being an African American and living in the South could have even more deadly consequences than expected, said lead author George Howard, Dr.P.H., professor and chair, Department of Biostatistics, University of Alabama at Birmingham School of Public Health.

"When it comes to your risk of stroke, you get a penalty for being African American, you get a penalty for living in the South, and you get an 'extra' penalty for being an African American living in the South," said Howard.

Howard and colleagues looked at stroke death data from 1997 through 2001 and calculated stroke mortality rates by race, age and state. They compared the findings in southern states (defined in this study as the "stroke belt" states: Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee plus Florida and Virginia), to non-southern states with large black populations: California, Illinois, Indiana, Maryland, Michigan, New Jersey, New York, Ohio and Pennsylvania.

"Knowing that African Americans die more of stroke than their white counterparts, we wanted to know if the difference was consistent across the nation, or if the magnitude of the African American excess mortality changes between regions," Howard said.

The researchers also compared the data by age group and found that the racial differences in stroke death were most pronounced between ages 45 and 64. With increasing age, the differences diminished and no racial differences were found after age 85.

The average stroke death rate for white men age 55 - 64, living in the South was .49 per 1,000, compared to .38 per 1,000 for white men living elsewhere – representing a 29 percent higher death rate for white men living in the South than white men not living in the South, Howard said.

Researchers found that the stroke death rate for black men age 55-64 living in the South was 1.59 per 1,000 while the rate was 1.05 for black men not living in the South. "So the stroke risk for African Americans living in the South is 51 percent higher, nearly twice as big as the 29 percent increase for whites living in the South," he said.

The numbers range considerably from state to state. For example, in New York, the risk of death from stroke among whites age 55-64 was 0.32 per 1,000 versus 0.68 per 1,000 for blacks in the same group. So in New York, blacks were 2.1 times more likely to die from stroke than whites. However, in South Carolina, the death rate from stroke for whites ages 55 - 64 is 0.50 per 1,000 versus 1.95 per 1,000 for same-aged African Americans. Thus, in South Carolina, African Americans are 3.8 times more likely to die from stroke than whites.

"These are whopping differences. The increase in risk of stroke for African Americans living in South Carolina is nearly twice as large as the increase for African Americans living in New York," Howard said.

The reasons for these racial differences between regions in the risk of dying from a stroke are not clear. However, Howard and colleagues have formed the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study group, which has a six-year government grant from the National Institute for Neurological Disorders and Stroke to examine what is causing these racial, age and geographic differences in stroke mortality. In the third year of the study, REGARDS will develop a study group of 30,000 people to better understand the stroke mortality risk factors for those who are both African American and southerners.

"Once we understand the causes for these differences, steps can be taken to correct them and save lives," Howard said.

Co-authors are Darwin R. Labarthe, M.D., Ph.D.; Jianfang Hu, M.S.; Deborah A. Levine, Ph.D. and Virginia J. Howard.