Blood Pressure and the Kidney: How Low Should It Be?

Observational epidemiology has identified the presence of a strong, positive, continuous, dose response relationship between level of blood pressure (BP) and risk of a variety of renal disease outcomes, including proteinuria, hypercreatinemia and end stage renal disease. This association has been noted throughout the entire range of systolic and diastolic BP but the risk of renal disease has been higher for systolic compared to corresponding levels of diastolic BP. In general, BP lowering has reduced the risk of renal disease. It is unclear, however, whether this applies equally to all population subgroups. There is also uncertainty regarding the optimal choice of antihypertensive drug therapy for preservation of renal function and the extent to which blood pressure should be lowered during antihypertensive therapy. Ongoing studies, including the African American Study of Kidney Disease and Hypertension (AASK) and Appropriate Blood Pressure Control in Diabetes (ABCD) trials may provide a more definitive basis for clinical decision making. AASK is a nationwide, multicenter clinical trial designed to compare the value of two levels of BP control and three antihypertensive drug regimens in reducing the rate of decline in renal function among African Americans with hypertension related renal insufficiency. The ABCD trial is a large, single center, randomized, controlled trial designed to compare the effects of moderate versus intensive BP lowering using two different antihypertensive drug regimens (calcium channel blocker and converting enzyme inhibitor) on several outcomes, including renal function, in normotensive and hypertensive type II diabetics. For the present, treatment should be consistent with the National High Blood Pressure Education Program recommendations.