Background: The racial/ethnic differences in post-stroke blood pressure (BP) trajectory and mortality risk are not fully understood. The current paper investigated differences in average systolic BP (SBP) during the 6 months following stroke and effects of average post-stroke BP on mortality risk among Blacks and Hispanics.
Hypothesis: Greater post-stroke BP levels will increase risk of mortality
Methods: We examined BP measurements in 6,016 stroke survivors within the New York City Health and Hospitals Corporation (NYC HHC) during the 6 months following stroke. Based on the average of all SBP measurements in this period, patients were classified into three groups: (1) SBP =140 mm Hg and =150 mm Hg). We used inverse probability weighting (IPW) to control for group differences in demographic factors, comorbidity, and anti-hypertensive medication use. We examined how 6 month SBP average related to mortality following stroke using Cox regression analysis. The mean duration of follow up after stroke was 2.6±1.5 years.
Results: The mean age was 57.9±13.0 years, 57.4% of patients were female, 49.1% were Black and 37.3% were Hispanic. Blacks were more likely than Hispanics to have an average post-stroke SBP >=150mm Hg (27% versus 17%). Group 1 (SBP <140) and Group 3 (SBP>=150) had higher risks of mortality (Group 1 HR=1.26, 95%CI=1.13-1.41; Group 3 HR=1.29, 95%CI=1.13-1.48) when compared to Group 2 (SBP 140-150). When controlling for ethnicity, these differences are no longer significant. In stratified analyses, the increased hazard in Group 1 was maintained in the sub-sample of Blacks (HR=1.47, 95%CI=1.25-1.72) but not in Hispanics (HR=0.95, 95%CI=0.79-1.15). The difference between Group 2 and Group 3 was not significant in either Black or Hispanic sub-samples.
Conclusion: Our findings demonstrate that having a post-stroke SBP below 140 mm Hg or above 150 mm Hg significantly increased individuals’ mortality risk, adjusting for demographic factors, comorbidity, number of BP readings, and location of healthcare. Post-stroke BP trajectory differed between Blacks and Hispanics, and had different effects on mortality. These findings have important implications for post-stroke hypertension care.