Traditional Risk Factors as the Underlying Cause of Racial Disparities in Stroke

Abstract

Background and Purpose Black/white disparities in stroke incidence are well-documented, but few studies have assessed the contributions to the disparity. Here we assess the contribution of “traditional” risk factors. Methods 25,714 black and white men and women, aged 45+ and stroke-free at baseline were followed for an average of 4.4 years to detect stroke. Mediation analysis employing proportional hazards analysis assessed the contribution of “traditional” risk factors to racial disparities. Results At age 45, incident stroke risk was 2.90 (95% CI: 1.72 – 4.89) times more likely in blacks than whites, and 1.66 (95% CI: 1.34 – 2.07) times at age 65. Adjustment for risk factors attenuated these excesses by 40% and 45%, respectively, resulting in relative risks of 2.14 (95% CI: 1.25 – 3.67) and 1.35 (95% CI: 1.08 – 1.71). Approximately one-half of this mediation is attributable to systolic blood pressure. Further adjustment for socioeconomic factors resulted in total mediation of 47% and 53% to relative risks of 2.01 (95% CI: 1.16 – 3.47) and 1.30 (1.03 – 1.65) respectively. Conclusions Between ages 45 to 65 years, approximately half of the racial disparity in stroke risk is attributable to traditional risk factors (primarily systolic blood pressure) and socioeconomic factors, suggesting a critical need to understand the disparity in the development of these traditional risk factors. Because half of the excess stroke risk in blacks is not attributable to traditional risk factors and socioeconomic factors, differential racial susceptibility to risk factors, residual confounding or non-traditional risk factors may also play a role.

Racial differences in albuminuria, kidney function, and risk of stroke

“…These factors, in turn, may partially explain racial differences in the association between albuminuria and stroke in this study. [32][33][34][35] When these results are coupled with previous findings from the REGARDS Study group showing that systolic blood pressure accounted for a substantial proportion of racial differences in stroke incidence, 20 the data collectively support the notion that black individuals have greater susceptibility to key risk factors for vascular injury like elevated systolic blood pressure and diabetes, contributing to the higher stroke risk long observed in this racial group.…”

Blood transcriptome changes after stroke in an African American population

“…The higher risk of stroke in the African American population has been well documented, and accordingly our area for investigation 11. While not part of this study, the expansion of these data to include Caucasians, may reveal additional gene expression profiles which are unique for racial susceptibility to stroke.…”

“…Traditional risk factors for stroke, such as obesity, hypertension (uncontrolled), and lifestyle only partially account for the higher risk 11. Furthermore, race‐associated differences in response to rt‐PA have been recently described 12, 13.…”

Associations Between Blood Pressure and Outcomes Among Blacks in the Jackson Heart Study

“…The Association of Black Cardiologists and the Working Group on Women's Cardiovascular Health published a statement of concern regarding these new guidelines, citing the disproportionate burden of hypertension among black patients15 and its role as a risk factor for mortality and incident cardiovascular disease with differential effects on black patients, such as stroke,16 HF,17 and CKD 18. These groups also expressed concern that the liberalized guidelines will have a differential effect on women, as older women are also disproportionately affected by hypertension and its downstream sequelae 19…”