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.