Blood pressure control, drug therapy, and kidney disease

The African American Study of Kidney Disease and Hypertension examined the effect on renal function decline of 2 blood pressure ( BP) goals ( low mean arterial pressure [ MAP] <= 92 versus usual MAP 102 to 107 mm Hg) and 3 antihypertensives ( ramipril versus amlodipine versus metoprolol). We previously reported that in all drug groups combined the BP intervention had similar effects on the primary outcome of glomerular filtration rate ( GFR) slope or the main secondary clinical composite outcome of end-stage renal disease ( ESRD), death, or GFR decline by 50% or 25 mL/min per 1.73 m(2). This report examines the effect of the BP intervention separately in the 3 drug groups. The BP effect was similar among the drug groups for either GFR slope or the main clinical composite. However, the BP effect differed significantly among the drug groups for the composite of ESRD or death ( P = 0.035) and ESRD alone ( P = 0.021). Higher event rates for amlodipine patients assigned to the usual BP goal ( 0.087 per patient-year for ESRD or death and 0.064 per patient-year for ESRD) were seen compared with the remaining groups of the factorial design ( range, 0.041 to 0.050 for ESRD or death; and range, 0.027 to 0.036 for ESRD). The low BP goal was associated with reduced risk of ESRD or death ( risk reduction 51%; 95% confidence interval, 13% to 73%) and ESRD ( 54%; 8% to 77%) for amlodipine patients, but not for patients assigned to the other drug groups. These secondary analyses suggest a benefit of the low BP goal among patients assigned to amlodipine, but they must be interpreted cautiously.