Acute infection contributes to racial disparities in stroke mortality.

OBJECTIVE: It is unknown whether racial differences in exposure to acute precipitants of stroke, specifically infection, contribute to racial disparities in stroke mortality.

METHODS: Among participants in the nationally representative Health and Retirement Study with linked Medicare data (1991-2007), we conducted a case-crossover study employing within-person comparisons to study racial/ethnic differences in the risks of death and hospitalization from ischemic stroke following acute infection.

RESULTS: There were 964 adults hospitalized for ischemic stroke. Acute infection increased the 30-day risks of ischemic stroke death (5.82-fold) and ischemic stroke hospitalization (1.87-fold). Acute infection was a more potent trigger of acute ischemic stroke death in non-Hispanic blacks (odds ratio [OR] 39.21; 95% confidence interval [CI] 9.26-166.00) than in non-Hispanic whites (OR 4.50; 95% CI 3.14-6.44) or Hispanics (OR 5.18; 95% CI 1.34-19.95) (race-by-stroke interaction, p = 0.005). When adjusted for atrial fibrillation, infection remained more strongly associated with stroke mortality in blacks (OR 34.85) than in whites (OR 3.58) and Hispanics (OR 3.53). Acute infection increased the short-term risk of incident stroke similarly across racial/ethnic groups. Infection occurred often before stroke death in non-Hispanic blacks, with 70% experiencing an infection in the 30 days before stroke death compared to a background frequency of 15%.

CONCLUSIONS: Acute infection disproportionately increases the risk of stroke death for non-Hispanic blacks, independently of atrial fibrillation. Stroke incidence did not explain this finding. Acute infection appears to be one factor that contributes to the black-white disparity in stroke mortality.