Level 2: Mid-level evidence
Vitamin E (α-tocopherol) supplementation 400 units daily for prevention of MI was evaluated in a randomized, placebo-controlled trial of 1,434 patients older than 55 years with type 2 diabetes mellitus and the haptoglobin 2-2 (Hp 2-2) genotype (Arterioscler Thromb Vasc Biol. 2008;28:341-347). The Hp 2-2 genotype is reported to occur in 36% of the general population and was present in 49% of patients screened for study entry. The study was terminated after 18 months due to significant results in an interim analysis. As a result of early termination, patients were followed for varying lengths of time; 450 patients did not receive the allocated intervention and 136 patients did not complete the trial.
Outcomes were analyzed for all patients by intention-to-treat analysis. Based on interim analysis, vitamin E was associated with a reduction in the combined outcome of MI, stroke, or cardiovascular death (2.2% vs. 4.7%, P=0.01, NNT 40) and MI (1% vs. 2.4%, P=0.04, NNT 72). There were no significant differences in the rates of stroke, cardiovascular mortality, or all-cause mortality.