The effect of a lower target blood pressure on the progression of kidney disease: Long-term follow-up of the modification of diet in renal disease study

Background: Hypertension is a risk factor for progression of chronic kidney disease. The optimal blood pressure to slow progression is unknown. Objective: To evaluate the effects of a low target blood pressure on kidney failure and all-cause mortality. Design: Long-term follow-up of the Modification of Diet in Renal Disease Study, a randomized, controlled trial conducted from 1989 to 1993. Setting: 15 outpatient nephrology practices. Participants: 840 persons with predominantly nondiabetic kidney disease and a glomerular filtration rate of 13 to 55 mL/min per 1.73 m(2). Intervention: A low target blood pressure (mean arterial pressure < 92 mm Hg) or a usual target blood pressure (mean arterial pressure < 107 mm Hg). Measurements: After the randomized trial was completed, kidney failure (defined as initiation of dialysis or kidney transplantation) and a composite outcome of kidney failure or all-cause mortality were ascertained through 31 December 2000. Results: Kidney failure occurred in 554 participants (66%), and the composite outcome occurred in 624 participants (74%). After Cox proportional hazards modeling and intention-to-treat analysis, the adjusted hazard ratios were 0.68 (95% Cl, 0.57 to 0.82; P < 0.001) for kidney failure and 0.77 (Cl, 0.65 to 0.91; P = 0.0024) for the composite outcome in the low target blood pressure group compared with the usual target blood pressure group. Evidence was insufficient to conclude that the benefit of a low target blood pressure differed according to the cause of kidney disease, baseline glomerular filtration rate, or degree of proteinuria. Limitations: The exact mechanism underlying the benefit of a low target blood pressure is unknown. Conclusions: Assignment to a low target blood pressure slowed the progression of nondiabetic kidney disease in patients with a moderately to severely decreased glomerular filtration rate.