Key Point

Even after adjustment for socioeconomic factors, rates of severe sepsis incidence and sepsis case fatality are significantly higher among black ICU patients than among white and Hispanic ICU patients. Hispanic patients have the lowest adjusted rates.

In a population-based study that included data for more than 71 million residents and nine million hospitalizations, black patients had the highest incidence rates of severe sepsis, compared with white or Hispanic patients—and higher ICU case fatality rates. Furthermore, incidence among Hispanic patients was lower than that among white patients after adjustment for regional urbanicity and poverty, said Amber E. Barnato, MD, MPH, of the Center for Research on Health Care, Pittsburgh, and colleagues in the February 1 American Journal of Respiratory and Critical Care Medicine. “It is possible that the overall mortality disparity among blacks could be partially ameliorated by focused interventions to improve processes and outcomes of care at the hospitals that disproportionately treat blacks,” the study authors suggested.

“One such intervention would be to examine administrative data for hospitals that treat a disproportionately high number of black patients, to assess quality of care based on the current guidelines for treating sepsis,” Dr. Barnato told Pulmonary Reviews. “The overall effect of quality improvement would be to reduce mortality nationally, not only among black patients but among patients of any race admitted to urban hospitals.”

Another potential intervention is early goal-directed therapy (ie, administered before admission to the ICU) proposed by Rivers et al, Dr. Barnato suggested, although she acknowledged that much more research is needed in that area.

POVERTY NOT A FACTOR

In the current study, Dr. Barnato and colleagues used data from the 2000 US census and corresponding hospital discharge datasets to identify severe sepsis cases in Florida, Massachusetts, New Jersey, New York, Virginia, and Texas. “These six states were chosen because they were large and diverse, had a significant proportion [27%] of the US population, and maintained high-quality hospital discharge data,” the study authors explained. Patients were categorized as non-Hispanic black, non-Hispanic white, and Hispanic; patients of other races or those whose race was not provided were not included in the analysis.

Severe sepsis was defined as the co-occurrence of International Classification of Disease, Ninth Revision, Clinical Modification codes for bacterial or fungal infectious process and acute organ dysfunction. Veteran’s Administration, military, and HIV hospitalizations were not included in the analysis. For each zip code, urbanicity was determined based on US Census assignment (ie, urban, suburban, rural), and poverty was determined based on the proportion of white residents living below the poverty line.

The mean age of the populace was 36.1; 54.4% were women. About 66% were white, 20% were Hispanic, and 14% were black. Nearly 73% lived in urban zip codes, and 59% lived in nonimpoverished zip codes (ie, those where less than 10% of white residents are below the poverty line).

Of the nine million hospitalizations, more than 282,000 met the criteria for severe sepsis (3.97 cases per 1,000 persons). Overall, severe sepsis incidence rose with age and male sex. According to data for age- and sex-standardized incidence by race, black patients had the highest rates (6.08 per 1,000 persons; rate ratio [RR], 1.7), followed by Hispanic patients (4.06 per 1,000 persons; RR, 1.1) and white patients (3.58 per 1,000 persons; RR, 1.0). However, after adjustment for differences in poverty in the region of residence, RR for sepsis incidence was 1.44 for black patients and 0.91 for Hispanic patients. Age- and sex-standardized case fatality rates for black, Hispanic, and white patients were 26.1%, 24.6%, and 24.2%, respectively.

POSSIBLE EXPLANATIONS

Black patients and, to a lesser degree, Hispanic patients were more likely than white patients to be treated in large, urban teaching hospitals. In turn, compared with the set of hospitals that disproportionately treat white patients, these hospitals had slightly higher rates of severe sepsis among those with infection (which could be a result of more conscientious coding of organ failure, the researchers remarked), higher ICU admission rates, and slightly higher ICU case fatality rates among all patients, regardless of race.

“Unmeasured severity of illness may account for some of the difference—that all of the patients who are admitted to large, urban teaching hospitals, regardless of race, are sicker than those admitted to suburban and rural hospitals,” Dr. Barnato commented. “Also, it could be that urban hospitals provide lower quality care.”

As an example, Dr. Barnato cited a previous study involving 139,000 hospitalized patients treated for acute myocardial infarction (AMI). The investigators found that, on average, blacks went to hospitals that had lower rates of evidence-based medical treatments, higher rates of cardiac procedures, and worse risk-adjusted mortality after AMI.

“Black patients’ treatment in hospitals with the lowest rate of compliance with evidence-based medical treatments, such as aspirin and β-blockers, explained their lower rates of evidence-based treatment nationally and certainly contributes to racial disparities in AMI mortality,” remarked Dr. Barnato. “A focal point for future research would be to see if you could find a similar type of story for sepsis.”

In the current study, the investigators suggested other possible reasons for the disparity, including a “socioeconomic health gradient among Hispanics [that] is less steep than among whites or blacks” and differences in genetic susceptibility—specifically, a tendency toward a more “exuberant” inflammatory response in black patients than in patients of other races.            

—Adriene Marshall

Suggested Reading
Barnato AE, Alexander SL, Linde-Zwirble WT, Angus DC. Racial variation in the incidence, care, and outcomes of severe sepsis: analysis of population, patient, and hospital characteristics. Am J Respir Crit Care Med. 2008;177(3):279-284.
Barnato AE, Lucas FL, Staiger D, et al. Hospital-level racial disparities in acute myocardial infarction treatment and outcomes. Med Care. 2005;43(4):308-319.
Rivers E, Nguyen B, Havstad S, et al; Early Goal-Directed Therapy Collaborative Group. Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med. 2001;345(19):1368-1377.

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