Racial variation in the incidence, care, and outcomes of severe sepsis: analysis of population, patient, and hospital characteristics

Abstract

Rationale: Higher rates of sepsis have been reported in minorities.

Objectives: To explore racial differences in the incidence and associated case fatality of severe sepsis, accounting for clinical, social, health care service delivery, and geographic characteristics.

Methods: Retrospective population-based cohort study using hospital discharge and U.S. Census data for all persons (n = 71,102,655) living in 68 hospital referral regions in six states.

Measurements and main results: Age-, sex- and race-standardized severe sepsis incidence and inpatient case fatality rates, adjusted incidence rate ratios, and adjusted intensive care unit (ICU) admission and case fatality rate differences. Of 8,938,111 nonfederal hospitalizations, 282,292 had severe sepsis. Overall, blacks had the highest age- and sex-standardized population-based incidence (6.08/1,000 vs. 4.06/1,000 for Hispanics and 3.58/1,000 for whites) and ICU case fatality (32.1 vs. 30.4% for Hispanics and 29.3% for whites, P < 0.0001). Adjusting for differences in poverty in their region of residence, blacks still had a higher population-based incidence of severe sepsis (adjusted rate ratio, 1.44 [95% CI, 1.42-1.46]) than whites, but Hispanics had a lower incidence (adjusted rate ratio, 0.91 [0.90-0.92]). Among patients with severe sepsis admitted to the ICU, adjustments for clinical characteristics and the treating hospital fully explained blacks' higher ICU case fatality.

Conclusions: Higher adjusted black incidence and the lower Hispanic incidence may reflect residual confounding, or it could signal biologic differences in susceptibility. Focused interventions to improve processes and outcomes of care at the hospitals that disproportionately treat blacks could narrow disparities in overall mortality from severe sepsis.

Figure 1.

Population-based rates of severe sepsis by age and race in six U.S. states, 2001. Black rates are depicted as diamonds, non-Hispanic white rates as squares, and Hispanic rates as triangles. In addition to higher rates among newborns, blacks' higher incidence rate is evident among adults as young as 20 years. Incidence rates among non-Hispanic whites and Hispanics are comparable throughout the age range. pop = population.

Figure 2.

Adjusted rate ratios of severe sepsis in six U.S. states, 2001. Rate ratios reflect age, race, sex, ZIP code–level poverty, and urbanicity-adjusted estimates of relative risk for severe sepsis. Blacks, men, and persons residing in poor and urban ZIP codes are at higher risk compared with whites residing in affluent, suburban areas; Hispanics and those living in rural regions have lower risk.