Race and ethnicity in trials of antihypertensive therapy to prevent cardiovascular outcomes: a systematic review

Abstract

Purpose: We wanted to systematically review (1) the participation of racial and ethnic minorities in clinical trials of antihypertensive drug therapy and (2) racial differences in the efficacy of these therapies for the prevention of cardiovascular outcomes.

Methods: MEDLINE, EMBASE, LILACS, African Index Medicus, and the Cochrane Library were searched from their inception to December 2005 for randomized controlled trials testing the efficacy of antihypertensive drug therapy in preventing myocardial infarction, stroke, revascularization, or cardiovascular death. MEDLINE was also searched from 2005 through 2006. The 2 authors independently assessed studies for inclusion and quality.

Results: Twenty-eight studies met inclusion criteria. Eight trials reported results by racial subgroup. Trials with black and Hispanic participants (ALLHAT, INVEST, VALUE) found similar primary outcomes, but ALLHAT found a greater magnitude of benefit for blacks on diuretic therapy compared with nonblacks. One trial (PROGRESS) compared Asians with non-Asians, reporting that angiotensin-converting enzyme inhibitors (vs placebo) were equally effective for preventing stroke in both groups. In the LIFE trial, post hoc analyses showed different outcomes for blacks and nonblacks, raising questions about the usefulness of angiotensin-receptor blockers as first-line antihypertensive agents in blacks. In 3 studies conducted exclusively in Asians (JMIC-B, FEVER, NICS-EH), calcium channel blockers were effective in preventing cardiovascular outcomes. No trials described cardiovascular outcomes in Native Americans.

Conclusions: Five trials made interethnic group comparisons; 4 had similar primary outcomes for ethnic minorities and whites. Increased minority participation in future studies is needed to determine optimal prevention therapies, especially in outcome-driven trials comparing multidrug antihypertensive treatment regimens.

Figure 1.

Flow diagram of systematic literature search and assessment. BP = blood pressure; CVD = cardiovascular disease; RCT = randomized controlled trial.

Figure 2.

Effect of treatment strategies on cardiovascular outcomes in racial/ethnic subgroups. *Exact 95% CI not provided; range extrapolated from article figure. ACE = antiotensin-converting enzyme; BP = blood pressure; CHD = coronary heart disease; CI = confidence interval; CV = cardiovascular; CVA = cerebrovascular accident; CVD = cardiovascular disease; HCTZ = hydrochlorothiazide; MI = myocardial infarction; RR = relative risk.