Nocturnal blood pressure in treated hypertensive African Americans Compared to treated hypertensive European Americans.

Previous studies have shown that African Americans (blacks) tend to have higher nocturnal blood pressure than European Americans (whites). The study presented here was undertaken to determine whether treatment of hypertension influences nocturnal blood pressure differently in blacks than in whites. To answer this question, this study measured nocturnal blood pressure by ambulatory blood pressure monitoring (ABPM) in treated hypertensive blacks and whites whose daytime blood pressures were comparable. Inclusion criteria for this study were: diagnosis of essential hypertension, absence of renal failure, and documentation of antihypertensive therapy, diabetic status, proteinuria status, and body weight. All of the black patients in our programs who underwent ABPM and met the above criteria were included in this study. White patients were included on the basis of having the same inclusion criteria as blacks and showing, by ABPM, daytime mean arterial pressure (MAP) in the same range as that of the blacks selected for this study. The results of nocturnal blood pressure were unknown to the investigators when the patients were selected for this study. In the blacks (N = 62) and whites (N = 72) selected for study, the mean daytime (0600 to 2200 h) MAP was 107 +/- 1 SE mm Hg for both the black and white cohorts. To assess nocturnal blood pressure, the period from 0100 to 0500 h was chosen because it likely encompassed an interval of sleep, which is associated with the nadir of nocturnal blood pressure. This interval was termed 0100 to 0500 h, "middle night." Mean middle night MAP was 97 +/- 12 mm Hg in blacks versus 90 +/- 14 mm Hg in whites (P