Black-white differences in stroke frequency: challenges for research

Studies of ethnic differences in frequency of disease can sometimes provide insights into etiologic mechanisms and, hopefully, lead to interventions that decrease risk and frequency of the disease. This principle can be applied to studies of stroke among blacks and whites. Blacks carry a disproportionate burden of strokes relative to the number of blacks in the population. In this paper, possible explanations for the differences are reviewed. It has been reported that certain risk factors for stroke, notably hypertension, are more common in blacks. However, it is unclear whether less access to medical care, difficulty with compliance in treatment programs, genetic differences in responsiveness to certain drugs or other genetic differences related to susceptibility are responsible for the consistently higher stroke frequency in blacks compared to whites. The frequency of stroke type also differs in these ethnic groups; whites are more prone to large vessel and embolic strokes whereas blacks suffer a higher frequency of small vessel and hemorrhagic stroke. When closely examining evidence, it is also unclear whether life-style, socioeconomic, or other factors can be implicated and even whether race plays any important role at all. All of these ethnic issues must carefully be considered in stroke data base research.