Abstract WMP50: Decomposition of Ethnic Differences in Stroke Recurrence--The Role of Education and Biological Stroke Risk Factors

Abstract

Background: Race/ethnic disparities in stroke recurrence have persisted in the last decade in the USA. These disparities are often attributed to ethnic differences in risk factor prevalence and socioeconomic status. Methods: Incident ischemic stroke (IS) cases were ascertained in the Brain Attack Surveillance in Corpus Christi (BASIC) study, in Texas, USA in 2000-2011. Cases validated by stroke physicians were followed until death or a maximum of 5 years to determine 5-year cumulative stroke recurrence risk. Multivariable regression analyses and effect decomposition analyses (EDA) were used to examine the degree to which ethnic disparities are explained by education and biological risk factors. Results: There were 3,184 incident IS cases and 340 recurrent strokes (see Table). The ethnic difference in 5-year recurrence rate was 4.4% (p=0.004) greater in Mexican Americans (MA) than non-Hispanic whites (NHW). The age- and sex-adjusted hazard ratio (HR) of 1.43 (95%CI: 1.13, 1.79) comparing MA to NHW was attenuated after adjustment for education (HR=1.35, 95%CI: 0.91, 2.00), and further adjustment for biological factors (HR=1.28, 95%CI: 0.85, 1.92). EDA revealed that 57% of the recurrence risk disparity was due to differential associations (HR) between observed risk factors and recurrence (see Table). The remaining 43% was due to ethnic differences in risk factor prevalence. Conclusions: Ethnic differences in the strength of the associations between risk factors and recurrence, most notably education, diabetes, atrial fibrillation and hypertension explained 57% of the recurrence risk disparity. Further investigation of why some risk factors are more strongly associated with stroke recurrence in one ethnic group compared with others could yield valuable information on ethnic-specific stroke pathogenesis and secondary prevention strategies.