FRIDAY, May 5, 2006 (HealthDay News) -- Nonwhite patients are more likely than white patients to have troublesome side effects from two common types of drugs used to fight high blood pressure, stroke and heart attack, British researchers report.
But the finding has to be viewed with caution, because experts say it's not clear whether race or other factors, such as more limited access to health care, may be to blame.
"It is impossible to know how much of the observed differences could be accounted for by factors such as these vs. underlying genetics," said Carlotta M. Arthur, a psychologist and an Andrew J. Mellon fellow at Smith College in Northampton, Mass.
Smith, a spokeswoman for the nonprofit Council for the Advancement of Health, was not involved in the study, which appears in the May 6 issue of the British Medical Journal.
The whole notion of race-based differences in drug efficacy and safety is a controversial one. The issue gained a higher profile last June when the U.S. Food and Drug Administration approved a drug for use only in black patients with heart failure, a condition where the heart progressively loses its ability to pump blood.
The approval came after a carefully controlled trial showed beneficial results for BiDil, a medication that combines two agents, hydralazine and isosorbide dinitrate, in that population.
In this latest review, researchers at the West Midlands Center for Adverse Drug Reaction Reporting in Birmingham first looked at 564 studies, then selected 24 that gave information on adverse side effects for at least two ethnic groups.
They found a higher risk for side effects in nonwhite patients for two cardiovascular drugs: ACE inhibitors, often prescribed for high blood pressure; and clot-preventing medications.
The studies found that black patients were three times more likely to experience the swelling called angio-edema than whites when taking ACE inhibitors. The risk of persistent cough for East Asian patients taking the drugs was almost three times higher than that of whites.
For clot-preventing therapy, the risk of excess bleeding was 50 percent higher in blacks than in non-blacks.
However, the researchers stressed the findings should be taken with a pinch of caution. First of all, studies that find ethnic differences in drug side effects may be more likely to be published than those finding no difference, skewing the data. And the report might not include unpublished trials, which might also have useful data, they said.
In addition, the report covered only drugs used for cardiovascular conditions. "For a much larger group of drugs, the data do not exist to confirm or refute the existence of ethnic differences in susceptibility to adverse drug reactions," the researchers wrote.
Nevertheless, the information that "the risk of harm may vary with ethnic group ... may help the clinician present more accurate and relevant data to their patients when prescribing therapy," the researchers said.
"I agree with the authors' assessment that the results of their meta-analysis should be interpreted cautiously," said Arthur.
"First, the terms 'race' and 'ethnicity' are used interchangeably, and neither is defined," she said. "Many, if not most, scholars agree that 'races' are socially and politically defined categories, with little if any genetic basis."
Many factors other than genetics could explain the differences found in the study, Arthur said -- most notably the fact that blacks tend to be poorer than whites and "frequently receive less preventive care and often are sicker when presenting for treatment."
"I think the best practice, rather than using race or ethnicity as a short cut or proxy, is for clinicians to practice good medicine with all of their patients, white or nonwhite, and assess all the factors that may actually account for the patients presenting condition," Arthur said.
Find out about efforts to eliminate racial disparities in health care at the U.S. Centers for Disease Control and Prevention.