Abstract 84: Where Should Interventions be Focused to Reduce the Black-white Disparity in Stroke Mortality? Insights From the Reasons For Geographic And Racial Differences In Stroke (REGARDS) Study

Abstract

Introduction: The study of racial disparities in stroke mortality should guide interventions to reduce these disparities. A higher mortality in blacks than whites could result from a higher incidence of stroke in blacks, a higher case-fatality of stroke in blacks, or both. Interventions focusing on primary prevention are needed if incidence is a major contributor to disparities, while interventions addressing treatment are a priority if case-fatality is a major contributor. Hypothesis: Higher stroke mortality in REGARDS will be attributable to higher incidence, higher case fatality, or both. Methods: 29,681 black and white participants aged 45+ were followed for stroke over 7 years. Fatal stroke (stroke mortality) was defined as a stroke event with death within 30-days, incident stroke included all stroke events (regardless of death), and case-fatality as the proportion of stroke events with death within 30-days. Black-white differences in stroke mortality and stroke incidence were assessed using proportional hazards models, and case-fatality using logistic regression (with adjustment for age and sex). Results: There were 954 incident events with 242 deaths within 30-days. We showed higher stroke mortality in blacks, with a black-white disparity in fatal stroke at young ages (at age 45, HR = 4.35; 95% CI: 1.94-9.76), but a declining magnitude of the disparity at older ages (at age 85, HR = 0.87; 95% CI: 0.56 - 1.35). The pattern was similar for incident stroke, although the magnitude of the black-white disparity was smaller (at age 45: HR = 2.40; 95% CI: 1.72 - 3.33; at age 85: HR = 0.95; 95% CI: 0.76 - 1.19). There was no evidence of a black-white disparity in case-fatality rate (OR = 1.26; 95% CI: 0.93 - 1.71). Conclusion: In a nationwide cohort, we found that the black-white disparity in stroke mortality was primarily attributable to a racial disparity in stroke incidence, not case fatality. Thus, interventions designed to reduce the black-white disparity in stroke mortality require a primary prevention focus aimed at reducing the disparity in stroke incidence. While effective interventions to improve stroke outcomes are needed, these data suggest that improving treatment after the initial event will not reduce black-white disparities in stroke mortality.