Long-term effects of antihypertensive agents on proteinuria and renal function.

BACKGROUND: Although many studies have examined the effects of antihypertensive agents on proteinuria and glomerular filtration rate in patients with kidney disease, many questions remain unresolved. These questions include whether the effects of agents differ, whether their effects are similar in diabetic and nondiabetic patients with renal disease, and whether the effects of any agents are independent of blood pressure reductions.
METHODS: We conducted a meta-analysis of studies obtained with MEDLINE and bibliographies from comprehensive reviews but included only investigations with follow-up times of at least 6 months. We combined data (1) in an analysis of randomized controlled trials, (2) in a separate univariate analysis of controlled and uncontrolled trials, and (3) using weighted multiple linear regression.
RESULTS: In 14 randomized controlled trials, angiotensin-converting enzyme inhibitors caused a greater decrease in proteinuria (pooled mean [95% confidence intervals], -0.51[-0.68 to -0.35], ln [treatment/control]), improvement in glomerular filtration rate (0.13 mL/min per month [0.10 to 0.16 mL/min per month]), and decline in mean arterial pressure (-4.0 mm Hg [-4.9 to -3.0 mm Hg]) compared with controls. In a multivariate analysis of controlled and uncontrolled trials, each 10-mm Hg reduction in blood pressure decreased proteinuria (regression coefficient [95% confidence interval] -0.14 [-0.22 to -0.06] ln [after/before]), but angiotensin-converting enzyme inhibitors (-0.45 [-0.58 to -0.32]) and nondihydropyridine calcium antagonists (-0.38 [-0.70 to -0.06]) were associated with additional declines in proteinuria that were independent of blood pressure changes and diabetes. Each 10-mm Hg reduction in blood pressure caused a relative improvement in glomerular filtration rate (0.18 mL/min per month [0.04 to 0.31 mL/min per month]), but among diabetic patients there was a tendency for dihydropyridine calcium antagonists to cause a relative reduction in glomerular filtration rate (-0.68 mL/min per month [-1.31 to -0.04 mL/min per month]).
CONCLUSIONS: Long-term beneficial effects of antihypertensive agents on proteinuria and glomerular filtration rate are proportional to blood pressure reductions and are similar in diabetic and nondiabetic patients with renal disease. In addition, angiotensin-converting enzyme inhibitors, and possibly nondihydropyridine calcium antagonists, have additional beneficial effects on proteinuria that are independent of blood pressure reductions.