Response to "Calcium Channel Blocker Therapy in Black Hypertensive Patients"

To the Editor: We thank Brewster and van Montfrans for their interest in our recent article.1 We meta-analyzed US studies of black and white hypertensive patients in order to assess evidence for differential treatment response to calcium-channel blockers (CCBs).2 Our results suggest that there is no rational basis for privileging racial identity of patients as a basis for treatment decisions regarding CCB monotherapy. We included only studies that recruited black and white patients with a uniform set of inclusion and exclusion characteristics in order to protect internal validity, since studies involving only one racial group may be idiosyncratic with respect to many factors, and therefore would threaten a valid black–white contrast. Brewster and van Montfrans assert that “excluding trials in black people only might create biased review results,” but this concern is rooted in the mistaken notion that the parameter of interest must be the black treatment effect. When the parameter of interest is the treatment effect disparity, inclusion of trials with only one or the other group is clearly the greater threat to validity. Brewster and van Montfrans privilege racial identity as a primary basis for treatment decisions, insisting that the black–white treatment differential is not important, but rather that one needs to know the best treatment option for black patients. In their own cited review article, they justify this focus by asserting that blacks are “a distinct biological entity” (ref. 3, p. 614). Needless to say, this is a nineteenth century perspective on human biologic variability that can no longer be considered the modern consensus. Likewise, these authors assert that hypertension in blacks is not only more severe, but also more resistant and more virulent. This, too, was a common conception in the past that has largely been relegated to the status of a myth.4 In conducting our systematic review, we did not limit ourselves to studies treating a particular range of blood pressures. Trials of CCB monotherapy generally restricted patients to diastolic blood pressures (DBP) between 95 and 115 mm Hg. Patients with DBP >110 mm Hg would often receive combination therapy. Brewster and van Montfrans express concern that these extreme blood pressures were not included in our review, but once again our eligibility criteria were designed to preserve internal validity. The previously published review article by Brewster and van Montfrans pools black subjects from the United States, the Caribbean, West Africa, and South Africa.3 Many of these populations have no discernable cultural, socioeconomic, genetic, or historical connection. Their only unifying characteristic is dark skin, a characteristic with no direct relationship to blood pressure. The position taken by these authors, that race must be the primary categorization in medical research and practice, is purely ideological. Our paper was a modest attempt to investigate the basis for this ideology, and we did not find any empirical support for such a position with respect to CCB monotherapy. The letter from Brewster and van Montfrans merely demands allegiance to this ideological position. It does not provide evidence in favor of such a view.