Key Components of a Daily POEM
Vitamin E not helpful, perhaps harmful
In patients with or without heart disease, does vitamin E supplementation decrease mortality?
» Clinical Question poses the question the study seeks to answer.
Vitamin E supplementation does not decrease all-cause mortality in patients with or without pre-existing heart disease. At higher doses it can actually be harmful, although the deleterious effect is small (number needed to treat to harm = 250). (LOE = 1b)
» Bottom Line summarizes the findings of the research and is designed to help clinicians understand how best to apply the results.
» LOE refers to a rating indicator provided by the Centre for Evidence-Based Medicine, Oxford. This factor allows the reader to discern an overall sense of how well this new information is supported.
Miller ER 3rd, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann Intern Med 2005; 142:37-46.
» Reference displays the article’s citation, which is conveniently linked to PubMed.
Meta-analysis (randomized controlled trials)
» Study Design identifies the procedures of the study (i.e., Meta-Analysis, randomized controlled trial, evidence-based practice guidelines, etc.)
» Funding indicates the financial backing of the study.
» Setting identifies the environment in which the study took place (i.e., outpatient, inpatient, emergency department, etc.)
The antioxidant property of vitamin E has led many to use it to prevent cardiovascular or cancer-related mortality. However, several studies and several previous meta-analyses have shown either no benefit or a slight increase in mortality with its use. The authors of this study performed a literature search in the usual way, searching MEDLINE, the Cochrane Clinical Trials Database, and reference lists and files. They included 19 randomized studies of almost 136,000 patients comparing vitamin E with a control or placebo group for at least 1 year and with at least 10 deaths in the trial. Study subjects varied and included elderly patients, healthy adults, and patient with cardiovascular disease. Study results were analyzed by intention to treat. The method of data extraction was not explained and studies were not graded or selected on the basis of quality. In the studies the baseline death rate was approximately 10%. Overall, there was no difference in all-cause mortality between the control group and placebo group. However, when comparing low-dose versus high-dose vitamin E (less than 400 IU/day vs 400 IU/day or more), differences were found. In the studies of lower doses, there was no benefit or detriment to vitamin E supplementation (relative risk = 0.98; 95% CI, 0.96-1.01). When high dose supplementation was studied separately, the risk was slightly but significantly higher in the supplemented group, with a number needed to treat to harm of 250 (143 - 998). The effect of vitamin E supplementation was not different when the results were evaluated by patient's sex or average age, or by the length of follow-up.
» Synopsis provides a brief overview of the study design and results. Although concise like an abstract, Daily POEMs adhere to our criteria for validity evaluation and only contain the most significant and applicable details.