South Dubbed "Stroke Belt"

More people who live in the southeastern U.S. die following a stroke than those living in any other region of the country, a statistic that’s resulted in this area being branded the “stroke belt”. The higher mortality rate, almost 50% greater in the southeast, has long been attributed to race and geographical differences; however, after factoring in variables such as race, age, and sex, researchers at UAB and the University of Vermont found that these aspects were insufficient to account for the entire discrepancy and actually represent only a minor part of the problem. So-called “non-traditional” factors may very well be responsible for this issue.

According to George Howard, Dr.PH. and Chairman of the Department of Biostatistics in the UAB School of Public Health, there may be numerous non-traditional factors that contribute to the increased number of deaths in the stroke belt, and sorting out their role will require additional studies.

“Inflammation and infection are the most important non-traditional factors,” he said. “Other potential causes are the micronutrients in our drinking water such as potassium and selenium. The outside temperature may affect the large difference in stroke mortality rate, as well as alcohol use, coagulation factors, and drugs such as aspirin, which thirty-five percent of the population takes as a prophylactic. And, although we are becoming aware of the effects of smoking, passive cigarette smoke has not been studied as thoroughly and could also contribute.”

While analyzing their data, the researchers also found that two traditional stroke risk factors, namely high blood pressure and diabetes, occur more frequently in the southeastern U.S. than in any other part of the country and contribute to the disparity in stroke mortality rate, both racially and geographically.

“… [the results] suggest that stroke risk factors, such as hypertension and diabetes, are more common in African Americans than whites, and thus might explain some of the racial disparities in stroke,” said Mary Cushman, M.D. at the University of Vermont College of Medicine and lead investigator on the study. “This suggests that efforts to better understand these differences, and improve treatments, might help reduce these disparities.”

Howard believes that these findings provide important clues that will help identify why the stroke belt exists in the first place and, furthermore, the reasons why African Americans are more susceptible to having a stroke.

“With this information, as a society we can begin to target the pathways that contribute to these immense disparities, each of which carries an additional cost to society in the neighborhood of three billion dollars annually. Individually, it provides information that as southerners and African Americans, at least a substantial portion of the increased risk of stroke seems to be going through hypertension and diabetes, which are controllable risk factors.”

According to Howard, since high blood pressure and diabetes are linked to stroke risk, preventative measures such as weight control and reduction of dietary sodium may decrease the incidence of stroke. On the other hand, if either condition should arise, continuous monitoring of blood pressure and blood glucose levels could also reduce the risk of having a stroke.

The stroke belt refers to Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee.

The work on this project stems from a large collaborative effort between various departments within UAB and from other universities around the country. This study is the Reasons for Geographic and Racial Differences in Stroke (REGARDS).

Published in the UAB Kaleidoscope newspaper, 01/27/2009