Monday, May 31, 2010

Effect of B-Vitamin Therapy on Progression of Diabetic Nephropathy

Penderita nefropati diabetik sering disertai dengan hiperhomosisteinemia, sehingga diberikan terapi vitamin B untuk menurunkan kadar homosistein.
Tapi ternyata pemberian terapi vitamin B menyebabkan penurunan GFR lebih besar, dan meningkatkan risiko vascular events (myocardial infarction, stroke, revascularization, and all-cause mortality)
 
Effect of B-Vitamin Therapy on Progression of Diabetic Nephropathy
A Randomized Controlled Trial
Andrew A. House, MD; Misha Eliasziw, PhD; Daniel C. Cattran, MD; David N. Churchill, MD; Matthew J. Oliver, MD;Adrian Fine, MD; George K. Dresser, MD; J. David Spence, MD

JAMA. 2010;303(16):1603-1609.
Context  Hyperhomocysteinemia is frequently observed in patients with diabetic nephropathy. B-vitamin therapy (folicacid, vitamin B6, and vitamin B12) has been shown to lower the plasma concentration of homocysteine.
Objective  To determine whether B-vitamin therapy can slow progression of diabetic nephropathy and prevent vascular complications.
Design, Setting, and Participants  A multicenter, randomized, double-blind, placebo-controlled trial (Diabetic Intervention with Vitamins to Improve Nephropathy [DIVINe]) at 5 university medical centers in Canada conducted between May 2001 and July 2007 of 238 participants who had type 1 or 2 diabetes and a clinical diagnosis of diabetic nephropathy.
Intervention  Single tablet of B vitamins containing folic acid (2.5 mg/d), vitamin B6 (25 mg/d), and vitamin B12 (1 mg/d), or matching placebo.
Main Outcome Measures  Change in radionuclide glomerular filtration rate (GFR) between baseline and 36 months. Secondary outcomes were dialysis and a composite of myocardial infarction, stroke, revascularization, and all-cause mortality. Plasma total homocysteine was also measured.
Results  The mean (SD) follow-up during the trial was 31.9 (14.4) months. At 36 months, radionuclide GFR decreased by a mean (SE) of 16.5 (1.7) mL/min/1.73 m2 in the B-vitamin group compared with 10.7 (1.7) mL/min/1.73 m2 in the placebo group (mean difference, –5.8; 95% confidence interval [CI], –10.6 to –1.1; P = .02). There was no difference in requirement of dialysis (hazard ratio [HR], 1.1; 95% CI, 0.4-2.6; P = .88). The composite outcome occurred more often in the B-vitamin group (HR, 2.0; 95% CI, 1.0-4.0; P = .04). Plasma total homocysteine decreased by a mean (SE) of 2.2 (0.4) µmol/L at 36 months in the B-vitamin group compared with a mean (SE) increase of 2.6 (0.4) µmol/L in the placebo group (mean difference, –4.8; 95% CI, –6.1 to –3.7; P < .001, in favor of B vitamins).
Conclusion  Among patients with diabetic nephropathy, high doses of B vitamins compared with placebo resulted in a greater decrease in GFR and an increase in vascular events.

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