Where to Focus Efforts to Reduce the Black–White Disparity in Stroke Mortality

An excess stroke mortality among blacks was documented as long ago as 1949 to 1951, with the black-to-white mortality ratios over 3× greater between the ages of 45 to 54 years and a declining black-to-white mortality ratio at older ages. These differences persist; Figure 1 shows the age-specific black-to-white stroke mortality ratio for the non-Hispanic US population between 2003 and 2007 (recruitment period for the Reasons for Geographic and Racial Differences in Stroke [REGARDS] study). There are numerous factors contributing to the temporal decline in stroke mortality, including prevention and improved control of stroke risk factors, including hypertension and diabetes mellitus, smoking cessation programs, and advances in poststroke care, such as telemedicine and health system designs to enhance stroke care. However, improvements in these factors seem to benefit both the white and black population and hence may not have contributed to changes in the magnitude of the black-to-white disparity for stroke mortality (in fact, the disparity seems to be increasing). To reduce the black–white disparity in stroke, we need to understand what factors contribute to the higher mortality in blacks and target interventions at these factors. Disease-specific mortality is a product of the incidence rate (number of people developing the disease) and the case fatality (proportion of those developing the disease die). Understanding whether higher stroke mortality in blacks is attributable to a higher incidence or case fatality is central to the effort to target interventions to reduce the disparity. Specifically, if higher incidence is the primary contributor, then efforts to reduce the disparity must focus on primary Background and Purpose—At age 45 years, blacks have a stroke mortality ≈3× greater than their white counterparts, with a declining disparity at older ages. We assess whether this black–white disparity in stroke mortality is attributable to a black–white disparity in stroke incidence versus a disparity in case fatality. Methods—We first assess if black–white differences in stroke mortality within 29 681 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort reflect national black–white differences in stroke mortality and then assess the degree to which black–white differences in stroke incidence or 30-day case fatality after stroke contribute to the disparities in stroke mortality. Results—The pattern of stroke mortality within the study mirrors the national pattern, with the black-to-white hazard ratio of ≈4.0 at age 45 years decreasing to ≈1.0 at age 85 years. The pattern of black-to-white disparities in stroke incidence shows a similar pattern but no evidence of a corresponding disparity in stroke case fatality. Conclusions—These findings show that the black–white differences in stroke mortality are largely driven by differences in stroke incidence, with case fatality playing at most a minor role. Therefore, to reduce the black–white disparity in stroke mortality, interventions need to focus on prevention of stroke in blacks. (Stroke. 2016;47:1893-1898. DOI: 10.1161/ STROKEAHA.115.012631.)