Blood Pressure Lowering and Renal Function-An Overview.

Large clinical trials for the treatment of hypertension have focused on stroke and cardiac end points with little attention paid to renal disease. There is substantial evidence suggesting that the treatment of hypertension may not adequately affect the progression to end stage renal disease (ESRD). The pathophysiology of hypertensivenephrosclerosis and its ultimate sequela, hypertensive ESRD constitutes a greater disease burden in African Americans when compared to any other racial group in the United States. The US Renal Data System has provided a population based confirmation of the frequently reported observation that African Americans between the ages of 20 and 45 years have a 17-fold higher incidence of hypertensive ESRD when compared to their white counter-parts. Paradoxically, this alarmingly high trend persists despite improvement in the clinical management of hypertension over the past two decades. Therefore, it is not clear if the presumed lack of effectiveness of anti-hypertensive therapy and observed racial differences in renal outcomes are due to inadequate blood pressure control, the use of antihypertensive agents without reno-protective properties, or whether they reflect other factors. The use of serum creatinine as an index of renal function has limitations as there is inter-correlation between systolic blood pressure, body mass index and creatinine which differ in black vs. white subjects and are not independently modified with the blood pressure intervention. Recent clinical trials have measured glomerular filtration as an index of renal function and find that control of BP may posses moderate benefit for the prevention of ESRD. There are two important clinical trials yet to be completed that will provide important information: 1) the Hypertension Optimal Treatment Substudy On Renal Function In Black And White Americans, will provide information on what is the optimal level to lower BP without compromising renal function, while 2) The African American Study of Kidney Disease and Hypertension will determine if ether the level of BP achieved or agents with putative renal protective properties will halt the progression to ESRD. The data from these trials may permit the formulation of accurate primary and secondary prevention strategies for the management of hypertensive renal disease.