Adventures (and Misadventures) on the Road to Understand (and Reduce) Disparities in Stroke Mortality

Racial and geographic disparities in stroke mortality have existed for over a half-century, and between ages of 45 to 65 are among the largest for any disease. For much of this period, the causes of the disparities have been mysterious; however, investments by NINDS and NHLBI are now providing insights regarding the causes of these disparities. Diverse and complementary study designs provide information on different aspects of the disparities in stroke. Vital statistics data track temporal patterns in stroke mortality, perhaps the ultimate index of the success in overcoming the disparities. Surveillance studies allow assessment of the contributions of incidence versus case fatality to the disparities in vital statistics mortality data, a distinction critical to effort to reduce the disparities. Finally, cohort studies give insights to the contribution of specific risk factors to disparities in either incidence or case fatality, allowing targeted interventions to be effective. While deaths from stroke mortality declined by a third over the most recent nine year period, there has been a 35% increase in the black-white disparity and little change in geographic disparities. Surveillance studies suggest that the black-white disparity is primarily attributable to differences in incidence, and also have unmasked Hispanic-white differences in incidence that are not apparent in mortality trends. Longitudinal cohort studies are suggesting multiple targets for intervention such as a multi-dimensional impact of blood pressure on the black-white differences, and indications that diet may be contributing to geographic disparities. The vital statistics mortality data currently provide a mixed message, with falling stroke mortality for all groups, but a more rapid fall for whites contributing to an increase in the magnitude of racial disparities in stroke. After suffering these disparities over a half-century, information is now emerging to allow us to better understand the underpinnings of the disparities and potentially enter a new era of targeted interventions to reduce these disparities.