Quality of care determines heart attack outcomes

Ninety days after acute myocardial infarction (AMI) - or heart attack - death rates for African Americans and white patients were found to be significantly higher in hospitals that disproportionately serve African-American patients than in hospitals that serve mainly white patients, according to a major new study led by researchers at Dartmouth Medical School.

The researchers suggest that quality of care, more than racial differences per se, determines AMI outcomes.

Based on the study findings, the investigators assert that targeted quality improvements at hospitals serving large shares of African Americans could enhance AMI care for all patients in those hospitals as well as potentially reduce black-white differences in AMI outcomes overall.

The analysis, published in the October 25, 2005, edition of Circulation: Journal of the American Heart Association, is one of the first to look at the association between the racial composition of a hospital's patients and health outcomes. The study was funded in part by the National Institute on Aging (NIA), a component of the National Institutes of Health, U.S. Department of Health and Human Services. Additional funding was provided by the Robert Wood Johnson Foundation.

"We know that disparities exist in the health and health care of African Americans and whites," explains Richard Suzman, Ph.D., Associate Director of the NIA for Behavioral and Social Research. "Some researchers focus on doctor-patient interactions as the major factor, while others give more weight to hospital quality. Potential remedies are quite different, depending on which set of factors predominates. This study sheds light on the mechanisms that may be at work in the case of hospital care and heart attacks."

Led by Jonathan Skinner, Ph.D., of Dartmouth Medical School, the research team analyzed the records of nearly all fee-for-service Medicare patients who were treated for AMI at U.S. hospitals between January 1, 1997, and September 30, 2001. More than 1.13 million older adults treated at 4,289 non-Federal hospitals were included in the study.

"Our research is consistent with the view that African Americans tend to go to hospitals where everyone gets lower quality care," Dr. Skinner says. "Targeting quality improvements for all patients at hospitals that disproportionately serve African Americans can improve overall survival, but also deliver an extra dividend by helping to shrink health disparities at the national level."

Skinner and colleagues classified hospitals that treated Medicare beneficiaries with AMI into 10 groups, depending on the extent to which they served African Americans. The 10 hospital groups ranged from those that admitted no African-American AMI patients to those where more than one-third (33.6%) of AMI patients were African American.

After adjusting for age, race, sex, and concurrent health problems such as diabetes, the risk-adjusted 90-day mortality after AMI was 20.1 percent in hospitals serving no African Americans and 23.7 percent in hospitals with the greatest share of black AMI patients -- a 19 percent higher rate. Heart attack patients treated at largely minority-serving hospitals were not sicker and did not have more severe heart attacks than patients at other hospitals, the study showed. In fact, the data show that AMI patients treated in hospitals with no African-American AMI patients were the sickest, as measured by an index of comorbidities, but had the lowest risk-adjusted mortality rates.

The differences in risk-adjusted hospital mortality outcomes also were not explained by patients' income, type of hospital ownership, the hospitals' annual AMI patient volume, region of the country, or urban status.

"We suspected that these differences could have been caused by the higher rates of poverty among the elderly African-American population, but this was not the case," Skinner notes. Moreover, he notes, the differences could not be attributed to the likelihood of the hospital providing certain post-AMI surgical interventions, such as coronary artery bypass grafting.

The researchers point out that in this study, 21 percent of the hospitals treated 69 percent of the elderly African-American AMI patients. The average Medicare AMI patient was treated in a hospital where 6.9 percent of AMI patients were African American. Relative to the hospital where the average AMI patient was treated, hospitals that disproportionately treated African Americans were more likely to be teaching facilities, more likely to be government-run (non-Federal), and less likely to be not-for-profit.

The researchers further suggest that, because many African-American Medicare beneficiaries live in urban areas with more than one hospital, disparities might be reduced by directing patients toward hospitals known to provide high-quality care.