Study Finds Blacks Have Higher Rate Of Mortality Than Whites Following Bypass Surgery

PHILADELPHIA, PA — November 16, 2000 — A new study showing that blacks have a higher mortality rate than whites as a result of coronary artery bypass surgery (CABG) suggests that blacks would benefit from earlier diagnosis of risk factors for heart disease and earlier treatment of heart disease.

The study also finds that hypertension is a particularly significant factor in mortality among blacks, who tend to suffer more from hypertension than do whites.

“As a whole, blacks have higher mortality rates following bypass surgery than whites, but these differences are most pronounced for hypertensive blacks and for black males,” explains study author Charles R. Bridges, MD, ScD, and assistant professor of surgery at the University of Pennsylvania School of Medicine and clinical director of cardiac surgery at Pennsylvania Hospital, one of the four hospitals of the University of Pennsylvania Health System. “There are subtle differences in the biology of hypertension in blacks and whites that need to be explored, including more severe, and frequent, ventricular hypertrophy, an enlargement of the heart’s chambers.”

Dr. Bridges and colleagues studied 25,850 black and 555,939 white patients who underwent CABG from 1994 through 1997 to determine whether race could serve as a predictor for mortality after surgery. The study, titled “The Effect of Race on Coronary Bypass Operative Mortality,” appears in today’s issue of the Journal of the American College of Cardiology.

The incidence of mortality as a result of CABG was less than four percent in both the black and white patient groups. When you compare the two groups, however, there is a 29 percent difference between blacks and whites in surgical mortality – even after taking in account the known risk factors among patients, such as re-operation, age, renal failure, and heart failure.

“This study suggests that race may be a surrogate marker for certain health risks,” Dr. Bridges explains. “If risk is higher in a particular ethnic group, we need to continue to investigate why. We need to look for subtle differences in biological variables or treatment. Once we discover what those are, we may be able to intervene in those situations with all patients – black or white – who have that particular type of biology. This kind of study can help all people.”

Above all, Dr. Bridges says, “it is important to emphasize that the mortality rate as a result of coronary bypass surgery is relatively low. Therefore, patients should continue to be referred for the surgery based on established clinical criteria, independent of race.”

Although previous research has found that the mortality rate is higher among women relative to men, the mortality rate among black females and white females is about the same. “This difference in the mortality rate, and its relationship between genders and races, is another opportunity to help us to better understand the biological nuances of heart disease,” Dr. Bridges says.

Aside from hypertension, he says, other findings in the study signal the need for more research into additional risk factors for CABG operative mortality.

First, researchers found that black patients were generally younger and sicker for their age than white patients. This suggests that race may be a marker for patients with a more rapid rate of progression of coronary artery disease specifically, and vascular disease in general.

Second, the finding in black patients of potentially more aggressive atherosclerosis, a hardening of the arteries that is often a precursor to heart attack and stoke, is also consistent with observed higher rates of cerebrovascular disease, hypertension, and renal disease in blacks relative to whites.

Third, as other studies have shown, race is often an indication of underlying differences in socio-economic, educational, behavioral, and cultural differences. Although these factors were not examined in this study, researchers stress that their potential influence on the outcomes of CABG should be the focus of further investigation.

“We should intensify efforts to ensure that blacks have better access to all interventional therapies in addition to preventative therapies,” Dr. Bridges says. “Other studies have shown that black patients are less likely to be referred for cardiac catheterization and coronary angioplasty, as well as CABG. Their relative lack of access to these procedures has been associated with lower long-term survival among blacks with heart disease and needs to be addressed.”

As Co-Founder and President of the Association of Black Cardiovascular and Thoracic Surgeons, Bridges is part of a growing number of African-American physicians who work to improve cardiovascular care for underserved populations in the U.S. and abroad. Bridges also serves as the chair for the Cardiac Surgery Committee of the Association of Black Cardiologists.

Dr. Bridges collaborated on this study with colleagues at the University of Florida Health Sciences Center in Jacksonville; Duke University Medical Center in Durham, North Carolina; and the Duke Clinical Research Institute in Durham.