Racial differences in mortality among patients with acute ischemic stroke: an observational study

Abstract

Background: Black patients are commonly believed to have higher stroke mortality. However, several recent studies have reported better survival in black patients with stroke.

Objective: To examine racial differences in stroke mortality and explore potential reasons for these differences.

Design: Observational cohort study.

Setting: 164 hospitals in New York.

Participants: 5319 black and 18 340 white patients aged 18 years or older who were hospitalized with acute ischemic stroke between January 2005 and December 2006.

Measurements: Influence of race on mortality, examined by using propensity score analysis. Secondary outcomes were selected aspects of end-of-life treatment, use of tissue plasminogen activator, hospital spending, and length of stay. Patients were followed for mortality for 1 year after admission.

Results: Overall in-hospital mortality was lower for black patients than for white patients (5.0% vs. 7.4%; P < 0.001), as was all-cause mortality at 30 days (6.1% vs. 11.4%; P < 0.001) and 1 year (16.5% vs. 24.4%; P < 0.001). After propensity score adjustment, black race was independently associated with lower in-hospital mortality (odds ratio [OR], 0.77 [95% CI, 0.61 to 0.98]) and all-cause mortality up to 1 year (OR, 0.86 [CI, 0.77 to 0.96]). The adjusted hazard ratio was 0.87 (CI, 0.79 to 0.96). After adjustment for the probability of dying in the hospital, black patients with stroke were more likely to receive life-sustaining interventions (OR, 1.22 [CI, 1.09 to 1.38]) but less likely to be discharged to hospice (OR, 0.25 [CI, 0.14 to 0.46]).

Limitations: The study used hospital administrative data that lacked a stroke severity measure. The study design precluded determination of causality.

Conclusion: Among patients with acute ischemic stroke, black patients had lower mortality than white patients. This could be the result of differences in receipt of life-sustaining interventions and end-of-life care.

Figure 1

Cumulative Hazards Plot of Death over Time

Figure 2. Hazard Ratio for Death by Race (Black vs. White)

*Age, gender, health insurance status, family income, principal diagnosis, 13 Charlson comorbidities, atrial fibrillation, hospital teaching status, hospital bed size, distance to the hospital, hospital site indicator and interactions were used to calculate the propensity score. ^†Including all of the covariates for direct risk adjustment in the entire study population. ^‡Elixhauser Index was used to calculate the propensity score.

Appendix Figure 1

Distribution of Propensity Score for Black and White Patients.

Appendix Figure 2

Kaplan-Meier Curves to Assess the Proportional Hazards Assumption

Appendix Figure 3

Schoenfeld Residual Plots to Assess the Proportional Hazards Assumption