Abstract P084: Racial Variation in Stroke Risk by Stroke Risk Factors

Abstract

Background: Black American adults exhibit a greater risk of stroke and disproportionate burden of stroke risk factors; however, it is unclear whether these stroke risk factors differentially impact stroke risk by race. Methods: In total, 126,018participants of the Women’s Health Initiative (11,389 black women and 114,629 white women), free of stroke and coronary heart disease at baseline (1993-1998), were followed for up to 17 years through 2010. Participants completed baseline clinical exams with standardized measurements of blood pressure and anthropometrics, medication inventory and self-reported questionnaires on socio-demographic, lifestyle/behaviors, diet and medical history. Incident total strokes were updated annually by questionnaire and confirmed by medical records. Multivariable Cox models estimated racial disparities in stroke overall and by across stroke risk factors. Results: We observed 4,344 stroke events over 1,496,314 person-years (py). In age-adjusted analyses, black women exhibited a 47% greater risk of total stroke compared to white women (hazard ratio [HR]=1.47, 95% CI: 1.33-1.63), which was attenuated toward the null (HR=1.05, 95% CI: 0.94-1.17) by further adjustment for stroke risk factors, which may be considered to be on the biological causal pathway. Disparities in stroke were two-fold higher for younger black (50-<60 years) compared to white women, with an incidence rate difference (RD) of 119/100,000 py. These disparities remained statistically significant after adjustment for stroke risk factors. For those 60-<70 years, the risk of stroke was 34% higher among black compared to white women, with a RD of 81/100,000 py No significant variation by other stroke risk factors was observed. Conclusions: Black women exhibited a significantly greater risk of total stroke compared to white women. Importantly, racial disparities were greatest among younger women aged 50-<60 years. Interventions targeted at younger black women may provide the greatest benefit in reducing disparities.