January 9th, 2014

Hospital Quality Helps Explain Some Racial Disparities in CABG Outcomes

It has long been known that racial disparities exist in health care. A large body of research has found that nonwhite patients have worse outcomes than whites. But it has been difficult to understand the underlying reasons for these disparities.  Now a new study offers evidence that, at least in the case of bypass surgery, a significant but by no means complete portion of this disparity is due to decreased access among nonwhites to high-quality hospitals.

In a paper published in JAMA Surgery, Govind Rangrass and colleagues analyzed Medicare data from 173,925 patients undergoing CABG. Of these patients, 8.6% were nonwhite. The mortality rate was 3.6% for the entire population. Nonwhite patients had a 34% increased risk of dying.

A key finding was that the third of hospitals that had the highest proportion of nonwhite patients (more than 17.7% nonwhite) also had the highest risk-adjusted mortality for both white and nonwhite patients (3.8% and 4.8%). In sharp contrast, the third of hospitals treating the fewest number of nonwhite patients (less than 2%) had the lowest risk-adjusted mortality for both white and nonwhite patients (3.2% and 3.7%). So at the best hospitals nonwhite patients did about as well as the white patients at the worst hospitals.

The investigators then adjusted for other patient factors and found that nonwhite patients were still at increased risk, with a 33% higher risk of death (odds ratio 1.33, CI 1.23-1.45). When patient factors were considered along with socioeconomic status and hospital quality, the investigators reported that they could then account for 53% of the racial disparity.

The authors speculated that the remaining unexplained disparity might be due to differences in disease severity: nonwhites may seek care at later or more severe stages of disease. Other possible factors mentioned are regional variations in the quality of hospitals, proximity to good hospitals, and segregated referral patterns.

They propose that “more should be done at a systems level to bring higher-quality care to disadvantaged populations,” but acknowledge that evidence-based policy solutions are lacking. “With a better understanding of the barriers to high-quality care, we will be able to design more effective programs to decrease health disparities,” they conclude.


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