Short-term effects of level of blood pressure control and antihypertensive drug regimen on glomerular filtration rate: the African American study of kidney disease and hypertension (AASK) pilot study.

The short-term (3-6 months) effects of interventions to prevent the progression of chronic renal disease, including a lower than usual level of blood pressure control, on renal function have been increasingly recognized. Ninety four non-diabetic African Americans with presumed hypertensive nephrosclerosis (diastolic blood pressure ≥ 95 mmHg) and moderately reduced renal function defined by a glomerular filtration rate (GFR) of 25-70 ml/min/1.73m2 were randomized, in a 2 by 3 factorial design, to a low mean arterial blood pressure (MAP) goal of ≤ 92 mmHg or a usual MAP goal of 102-107 mmHg and to an antihypertensive drug regimen with either a calcium channel blocker (CCB; amlodipine), angiotensin converting enzyme inhibitor (ACEi; enalapril), or beta blocker (BB; atenolol). At 3 months post-randomization, mean GFR was similar (53.0 vs 53.7) to baseline levels in participants randomized to the low MAP goal (n=44) whereas the mean GFR increased by 3.9 ml/min/1.73m2 (p=.02) in participants randomized to the usual MAP goal (n=46). During the same period of time, mean GFR increased significantly in participants randomized to the CCB regimen (n=28) (5.7 ml/min/1.73m2; P=.01) but not the BB regimen (n=31) (1.7 ml/min/1.73m2; P=.10). In contrast, a non-significant decrease in mean GFR of 1.1 ml/min/1.73m2 was observed in participants randomized to the ACEi regimen (n=31) (p=.52). Changes in GFR at 3 months were significantly different among the three drug regimens (p=.04). We conclude that the magnitude of short-term effects of blood pressure control and antihypertensive drug regimens on GFR should be considered when estimating sample size for clinical trials designed to evaluate the effects of these interventions on long-term changes in GFR slope.