George Howard, Claudia S Moy, Virginia J Howard, Leslie A McClure, Dawn O Kleindorfer, Brett M Kissela, Suzanne E Judd, Fredrick W Unverzagt, Elsayed Z Soliman, Monika M Safford, Mary Cushman, Matthew L Flaherty, Virginia G Wadley

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. 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. 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. 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.