Studies Examine Racial Disparities In Response to Heart Disease Drugs

Today's New England Journal of Medicine features two studies analyzing racial differences in patient response to specific ACE inhibitors and beta blockers, drugs given to patients with heart conditions. The studies "provide an intriguing window on a confounding problem" -- why blacks suffer from heart disease at a higher rate and are twice as likely as whites to suffer from heart failure, the Wall Street Journal reports (Winslow, Wall Street Journal, 5/3). The first study examined responses of black and white patients with left ventricular dysfunction to enalapril, an ACE inhibitor. The study analyzed 1,196 white patients and 800 black patients who participated in prevention and treatment trials comparing enalapril to a placebo. Researchers matched four white patients to each black patient based on age, sex and treatment assignment. Even though matched patients had "similar demographic and clinical characteristics," in white patients, enalapril therapy resulted in a 44% reduction in the risk of hospitalization because of heart failure, while the drug "no significant reduction" among black patients, researchers found. In addition, the drug was linked with "significant reductions" in systolic and diastolic blood pressure among whites but not among blacks. Researchers said that diet, compliance and access to care could contribute to the discrepancies, adding that "racial categorization is only a surrogate marker for genetic or other factors responsible for individual responses to therapy." Additional research addressing the "efficacy of therapies for heart failure in black patients" is necessary, the researchers determined (Exner et al., New England Journal of Medicine, 5/3).

Better with Beta Blocker
In the second study, researchers analyzed racial differences in patient response to the beta blocker, carvedilol. In the study, 217 black and 877 non-black participants with heart failure received either carvedilol or a placebo twice per day for up to 15 months. Researchers found that carvedilol lowered the risk of death "from any cause" or hospitalization "for any reason" by 48% in black patients and 30% in non-black patients. In addition, carvedilol reduced the risk of "worsening heart failure" -- heart failure that leads to death, hospitalization or a "sustained increase" in medication -- by 54% in black patients and 51% in non-black patients. The drug also improved "functional class, ejection fraction and the patients' and physicians' global assessments" in patients from both groups, leading the researchers to conclude that the benefits of the drug were "apparent and of similar magnitude in both black and non-black patients with heart failure" (Yancy et al., New England Journal of Medicine, 5/3).

Should Race Be a Factor in Research?
NEJM also features two editorials on the subject of race and research. The first, by Dr. Robert Schwartz, an NEJM editor, states that although scientists in both studies divided participants into groups by race, they have "no plausible biologic justification for making such distinctions." Schwartz writes, "Race is a social construct, not a scientific classification. ... A racial designation in the context of medical management not only defies everything we have learned from biology, genetics and history, but also opens the door to inequities in medical care" (Schwartz, New England Journal of Medicine, 5/3). The second editorial, by Dr. Alastair Wood of the Vanderbilt University School of Medicine, states, "The logical extension of the studies ... will be the genetic determinants of the reported racial differences, rather than attention to the external phenotypic manifestations of race. The identification of such genetic determinants will make possible better definition of the targets of current and future therapies and will lead to therapies that are more specific" (Wood, New England Journal of Medicine, 5/3).

No Change in Treatment Needed
Speaking to the Wall Street Journal, Dr. Clyde Yancy, a cardiologist at the University of Texas Southwestern Medical Center and lead author of the carvedilol study, said, "There is virtually an epidemic of heart failure among African Americans. We need better ways to treat it." Yancy said he was "encouraged" by his study's results, because previous research had found that beta blockers were "less effective" in African-American patients (Wall Street Journal, 5/3). "There was a concern that black patients did not respond to beta blockers but we are showing that these drugs are a very good option for African Americans," he said (Ricks, Newsday, 5/3). Although the enalapril study found disparities in the responses of black and white patients, lead study author Dr. Derek Exner of the University of Calgary said that the drug should "still be used as standard treatment for heart failure (Nano, AP/Philadelphia Inquirer, 5/3). Daniel Dries, a heart failure expert at the University of Texas Southwestern Medical Center and co-author of the enalapril study, added that the results "don't mean African-American patients should be taken off an ACE inhibitor," but rather that doctors should increase the dose "gradually" to "see if response improves" (Wall Street Journal, 5/3).