Proteinuria and hypertensive nephrosclerosis in African Americans.

Proteinuria is a known risk factor for both renal disease progression and cardiovascular morbidity and mortality in hypertensive populations. African Americans are among the highest risk groups for development of renal disease in the setting of hypertension and suffer a disproportionate burden of end-stage renal disease attributed to hypertension. Population-based studies indicate that African Americans have higher rates of albuminuria compared to non-African Americans in part due to higher rates of hypertension and diabetes in African Americans as compared to non-Hispanic whites for example. The African American Study of Kidney Disease and Hypertension (AASK) Trial was a prospective long-term clinical trial that examined the effect of aggressive blood pressure lowering versus usual blood pressure lowering in three different classes of antihypertensives on renal outcomes in approximately 1200 African Americans with hypertensive nephrosclerosis. Two thirds of trial participants had < 300 mg protein, and one third had > or = 300 mg of protein in a 24-hour urine specimen at baseline. Those with > 300 mg protein excretion compared to those with < 300 mg protein excretion at baseline had more rapid decline in renal function and ESRD events. Moreover, lower levels of proteinuria than previously thought may be important for identifying those at higher risk for kidney disease progression. The AASK cohort study, a follow-up to the trial, is now underway. The longer term follow-up will provide new insights into proteinuria and other risk factors for progression of kidney disease in hypertensive nephrosclerosis.