African American Study of Kidney Disease and Hypertension Study (Clinical Trial)

The African American Study of Kidney Disease and Hypertension study (AASK Trial) was a multi-center, randomized clinical trial that investigated the effects of blood pressure (BP) control and the use of specific antihypertensive regimens on the progression of chronic kidney disease (CKD). The study was designed to address the high incidence of CKD in African Americans with hypertension. A two by three factorial study design, including two levels of BP control as defined by mean arterial pressure (MAP) and three different anti-hypertensive regimens, was used. Participants were randomized into two levels of BP control groups, either a goal MAP < 92 mmHg or a goal MAP between 102-107 mmHg inclusive.. The antihypertensive drugs used for treatment were amlodipine, a calcium channel blocker; ramipril, an angiotensin-converting enzyme inhibitor; and metoprolol, a β-blocker. The trial was double-blind (drug administration only). The change in glomerular filtration rate (GFR) as determined by iothalamate clearance was measured as the primary outcome to test the regimens’ efficacy in slowing the rate of decline of kidney function.

The study showed that the angiotensin-converting enzyme inhibitor ramipril was more effective than the beta blocker metoprolol or the dihydropyridine calcium channel blocker amlodipine in slowing the rate of GFR decline. The results suggest that reduction in blood pressure to levels below those currently advocated for cardiovascular risk reduction does not provide readily identifiable benefits to African Americans with hypertensive nephrosclerosis.