Background: A controlled trial reported cardiovascular benefits of vitamin E in terminal renal insufficiency. There are no data for renal insufficiency before the stage of terminal renal failure. We evaluated effects of vitamin E supplementation on cardiovascular and renal outcomes in 993 people with a serum creatinine > or =1.4 to 2.3 mg/dL.
Methods: Post-hoc analysis of a randomized trial that compared treatment with natural source vitamin E (400 IU/day) to placebo in 9541 people, 993 of which had renal insufficiency. Participants had either known cardiovascular disease or diabetes and at least one additional coronary risk factor. Exclusion criteria included a serum creatinine > 2.3 mg/dL and dipstick-positive proteinuria. The primary study outcome after an average of 4.5 years was the composite of myocardial infarction, stroke, or cardiovascular death. Secondary outcomes included revascularizations, total mortality, and clinical proteinuria.
Results: In renal insufficiency, vitamin E supplementation had a neutral effect on the primary study outcome, on each component of the composite primary outcome, and on all secondary outcomes. Two hundred twenty-four primary outcomes, 23% of the vitamin E group and 22.1% of the placebo group, relative risk 1.03 (95% CI, 0.79-1.34; P= 0.82), were observed, and 585 secondary outcomes, including death in 17% and 18.8% of the vitamin E and placebo groups, respectively (RR 0.88, 95% CI, 0.66-1.18; P= 0.40). There was no effect of vitamin E on progression of proteinuria.
Conclusion: In people with mild-to-moderate renal insufficiency at high cardiovascular risk, vitamin E at a dose of 400 IU/day had no apparent effect on cardiovascular outcomes.