Adverse reactions to medications result in significant mortality and other health and economic problems. In Britain, approximately 7 percent of hospital admissions are attributed to drug reactions. Ethnicity is one of many factors implicated in adverse drug reactions. Some drugs have been shown to have different metabolic and therapeutic effects in certain ethnic groups, and cultural practices may increase the risk of adverse drug reactions. Nevertheless, the extent to which ethnicity affects susceptibility to adverse reactions to common medications remains unclear. McDowell and colleagues reviewed the evidence for increased susceptibility to adverse reactions to cardiovascular drugs in certain ethnic groups.

The authors searched electronic databases to identify studies that compared adverse drug reactions associated with cardiovascular drugs in at least two ethnic groups. In addition, they attempted to include unpublished data referenced in these papers. Each study was assessed for bias in selection, performance, attrition, and detection. Review articles, case reports, and case series were excluded from the study. Of more than 3,000 studies identified, only 24 met criteria for inclusion in the analysis.

Six studies of angiotensin-converting enzyme (ACE) inhibitors concerned angioedema, and two concerned cough. Analysis of the pooled data showed the relative risk (RR) of angioedema for black patients compared with white patients to be 3.0. For ACE inhibitor–associated cough, the risk was enhanced for patients from East Asia (i.e., China, Korea, or Japan), with a RR of 2.7, compared with white patients.

In black patients, thrombolytic therapy was associated with increased risk of moderate or severe bleeding (odds ratio [OR] = 1.9) and with intracranial hemorrhage (RR = 1.5). Nonwhite patients also were more likely to be admitted to the hospital because of bleeding after oral anticoagulation therapy for deep venous thrombosis (hazard ratio = 1.6).

Individual studies of hypertensive therapy reported an increased risk of depression with hydrochlorothiazide (Esidrex) and with all hypertensive therapy in blacks compared with whites. Another study found a significantly increased rate of headache in black patients treated for hypertension (17 percent compared with 2 percent for nonblack patients). A retrospective study of East Asian patients found a 26 percent rate of reported adverse drug reactions during treatment for hypertension compared with 13 percent for whites.

Digitalis therapy also was associated with an increased risk of hospital admission for adverse drug reactions in black patients compared with white patients (OR = 1.37).

The authors conclude that some evidence supports ethnic variations in susceptibility to adverse drug reactions during therapy with common cardiovascular medications. They note the many difficulties in studying this topic, including varying definitions and documentation of ethnicity, confounding factors, potential for study or reporting bias, and incomplete recognition or reporting of adverse drug reactions. Nevertheless, they propose that individual patients may be at increased risk of adverse reactions to medications because of ethnicity, and they call for more research on the role of ethnicity in the effectiveness and safety of medications.