DURHAM, N.C. -- African-American patients with coronary artery disease die at a significantly higher rate than white patients with the same degree of disease, according to an analysis of more than 20,000 patients by cardiologists at the Duke Clinical Research Institute.
Among patients diagnosed with serious coronary disease who were followed for an average nine years, the researchers found that blacks have had a 36 percent survival rate while whites have had a 46 percent survival rate.
The researchers said the disparity can be partially by the findings that blacks tend to have higher rates of other medical conditions, which can complicate or contribute to heart problems, and that blacks do not receive coronary artery bypass surgery as often. But the researchers stressed that other unproven factors almost certainly are involved and that further research is needed to identify them and quantify their contributions.
"As prevention becomes a key point of emphasis in treating heart disease, it is vitally important to identify risk factors and to act on them," said cardiology fellow Kevin Thomas, M.D., who reported the results of the analysis on Sunday, Nov. 12, at the annual scientific sessions of the American Heart Association, in Chicago.
The study was supported by a young investigator award from the Association of Black Cardiologists and the Duke Clinical Research Institute.
"Past studies from which risk factors have been derived provide great information about heart disease in white men, but the studies have included few minorities and women," Thomas said. "Cardiovascular disease is the leading cause of death for blacks and whites in the United States, and yet there is a paucity of information on the long-term prognosis for blacks."
For the analysis, Thomas and colleagues consulted the Duke Database for Cardiovascular Disease, a compilation of data on heart patients who come to Duke University Medical Center for diagnosis and treatment. The team analyzed the outcomes of 21,054 patients seen between 1986 and 2004 and found to have serious coronary artery disease. Of those patients, 3,177 were black.
In general, the black patients tended to be younger and more often female, and they had higher rates of hypertension, diabetes, heart failure or previous heart attacks, Thomas said. After the team statistically accounted for those patient characteristics, the disparity in death rates persisted, Thomas said, meaning that other factors must be contributing to the disparity.
"When we looked at the extent of coronary disease, we found there was little difference between blacks and whites," Thomas said. "However, when we looked at the incidence of procedures received by patients within 30 days of cardiac catheterization, we found that whites were 12 percent more likely to receive coronary bypass surgery."
According to Thomas, it is not clear why blacks did not receive coronary bypass surgery as often as whites. One possible explanation, he suggested, is that some physicians may have been biased against blacks, whether intentionally or not, as has been shown in past Duke studies. He also said that many blacks have a historical mistrust of the medical system, and so black patients might not have been as willing to undergo coronary bypass surgery, an invasive procedure.
"A big part of that mistrust is communication," Thomas said. "If black patients don't have a complete understanding of the procedure, or if it is not explained well, they may decline the procedure. If a physician or health care provider explains the procedure and what it entails, more black patients might agree to the surgery -- especially if the person doing the explaining were black or trained to be culturally sensitive."
Aside from less use of bypass surgery, other factors also likely contributed to the observed disparities and need to be investigated in future studies, Thomas said.
For example, he noted that heart patients typically receive optimal care while they remain in the hospital.
"However, when patients return to their home environment, they face many challenges and barriers to following their doctor's advice and maintaining a healthy lifestyle," he said. "Patients may not fill their prescriptions, or if they do, they may not take the medication over the long term. Often, patients may revert to bad habits in terms of diet and smoking. They may not return for follow-up doctor visits or they may not have doctors that they see regularly. These obstacles may disproportionately affect minority populations."
To learn more about what treatments work best for individual patients, Thomas said, the medical community should mount concerted efforts to attract more blacks into participating in clinical trials.
"There has been a history in the black community of mistrust of the health care system, which has often been seen as using blacks in medical experiments," Thomas said. "To overcome this mistrust, we must learn how to communicate in a culturally sensitive manner. Not all people are the same, so you have to tailor your communication to your patient if you want to improve outcomes."
He said the Association of Black Cardiologists, which is respected and trusted in the black community, is working in various ways to improve the levels of minority enrollment in clinical trials of heart therapies.
Also, he said he expects that results from the current Jackson Heart Study, a National Institute of Health supported study which is focusing on cardiovascular disease among the black residents in and around Jackson, Miss., will yield important data. This study, he said, may provide advances in the manner of the classic Framingham Heart Study, which began in 1948 and still continues, though it focuses primarily on white men.
Other researchers who participated in the Duke analysis were Emily Honeycutt, Linda Shaw and Eric Peterson.