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High-dose vitamin B therapy associated with declines in renal function, increased rates of vascular events in patients with diabetic nephropathy, DIVINe trial data indicate

Friday, May 07 2010 | Comments

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What's This? Among patients with diabetic nephropathy, high doses of B vitamins are associated with more rapid decline in renal function and an increased risk of vascular events as compared with placebo, in spite of an apparent homocysteine-lowering effect, according to findings from the DIVINe study.

The double-blind study, which was conducted in Canada, included 238 patients with type 1 or type 2 diabetes and a clinical diagnosis of diabetic nephropathy in the modified intent-to-treat population. The participants were randomized to receive once-daily treatment with a single tablet that contained folic acid 2.5 mg, vitamin B6 25 mg, and vitamin B12 1 mg, or matching placebo. The median follow-up period was 32.2 months.

The main outcome measure was the change in radionuclide glomerular filtration rate (GFR) from baseline to month 36. Additional outcome measures included the need for dialysis; a composite endpoint of myocardial infarction, stroke, revascularization, and all-cause mortality; and changes in plasma total homocysteine levels.

The study authors noted that, as expected, plasma homocysteine levels decreased significantly with active treatment as compared with placebo (a mean decrease of 2.2 mcmol/L vs a mean increase of 2.6 mcmol/L, respectively) at 36 months.

However, contrary to what the researchers expected, radionuclide GFR declined significantly more with vitamin B therapy (-16.5 mL/min/1.73 m2) than with placebo (-10.7 mL/min/1.73 m2).

In addition, the 36-month risk of the composite secondary endpoint was 2-fold greater in the active treatment group as compared with the placebo group, reflecting a statistically significant increase in risk.

"Given the recent large-scale clinical trials showing no treatment benefit, and our trial demonstrating harm, it would be prudent to discourage the use of high-dose B vitamins as a homocysteine-lowering strategy outside the framework of properly conducted clinical research," the researchers concluded. (House AA, et al. JAMA 2010;303:1603-1609.)

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