DALLAS, March 3 -- The initial brain damage caused by a stroke is more severe in African Americans than Caucasians, however researchers say this doesn't completely explain the higher toll stroke takes on African Americans compared to Caucasians.
That's according to a new study in this month's Stroke: Journal of the American Heart Association. The study included 984 men -- about 30 percent of whom are African American -- who were hospitalized at one of nine Veterans Affairs hospitals between April 1995 and March 1997. Utilizing a stroke severity scale -- the Canadian Neurological Scale (CNS) -- to retrospectively measure severity from medical record information, researchers found that African-American stroke patients had a greater severity of stroke than Caucasians.
The CNS scale goes from 0 to 11.5, with lower numbers equaling greater severity of stroke. The average CNS score for African Americans was 7.96, compared to 8.32 for Caucasians.
To determine the CNS severity of each patient's stroke, researchers looked at the patient's level of consciousness, orientation, language and motor function. The investigators created stroke scores of mild, moderate and severe impairment based on the scale. Mild was defined as having no motor deficits and severe impairment was classified as comatose or aphasic, which is the inability to communicate either verbally or in written form.
Researchers say that the increased severity of strokes doesn't completely explain the high rate of death and disability from stroke among blacks compared to whites. They suggest that other factors are involved, such as different risk factors, poorer control of risk factors or greater susceptibility to the disease.
"This suggests that we should work with the African-American community to better control risk factors for stroke and provide more education to emphasize the healthy behaviors that might reduce the likelihood of a severe stroke and its devastating consequences," says the study's senior author, Ronnie D. Horner, Ph.D., of The Department of Veterans Affairs and Duke University Medical Center, Durham, N.C.
Prior studies have suggested that lack of access to care may be a reason why African Americans are more adversely affected by stroke. However, researchers say that in this study, African Americans and Caucasians arrived at the hospital at about the same time following a stroke. Researchers say it's difficult to determine exactly why strokes are more severe; they add that African Americans are more susceptible to hemorrhagic strokes caused by bleeding in the brain. High blood pressure, which is more common in African Americans than whites, is a major risk factor contributing to hemorrhagic strokes.
Previous research has shown that even though hemorrhagic strokes only account for about 20 percent of all strokes, the damage -- reflected by death and disability rates -- is significantly worse when compared to people who have ischemic strokes caused by blockages in the blood vessels. Other studies have examined socioeconomic or behavioral factors that may contribute to the increased stroke mortality, however this is the first to look at the severity of the stroke as determined by factors such as symptoms and neurological function.
The average life expectancy for whites is at an all-time high -- 77 years -- compared to 71 years for blacks. Stroke is a major contributor to that difference. African Americans ages 35 to 74 are more likely to have a stroke compared to Caucasians and more likely to die from a stroke.
Co-authors are Michael R. Jones, B.S.; Lloyd J. Edwards, Ph.D.; Jennifer Hoff, M.S.; S. Beth Armstrong, B.A.; Carol A. Smith-Hammond, Ph.D.; David B. Matchar, M.D.; and Eugene Z. Oddone, M.D.
NR00-1125 (Stroke/Horner)
Media advisory: Dr. Horner may be reached by phone at (919) 286-6936, by fax at (919) 416-5836 or by e-mail at horne003@duke.edu. (Please do not publish numbers.)