Getting started in research: systematic reviews and meta-analyses

Objectives: Systematic reviews are one of the major building blocks of evidence-based medicine. This overview is an introduction to conducting systematic reviews and meta-analyses. Conclusions: Systematic reviews and meta-analyses of randomised controlled trials (RCTs) represent the most robust form of design in the hierarchy of research evidence. In addition, primary data do not have to be collected by the researcher him/herself, and there is no need for approval from an ethics committee. Systematic reviews and meta-analyses are not as daunting as they may appear to be, provided the scope is sufficiently narrow and an appropriate supervisor available

Effect of Supplemental Vitamin E for the Prevention and Treatment of Cardiovascular Disease

OBJECTIVE: To evaluate and synthesize the evidence on the effect of supplements of vitamin E on the prevention and treatment of cardiovascular disease. DESIGN: Systematic review of placebo-controlled randomized controlled trials; meta-analysis where justified. MEASUREMENTS AND MAIN RESULTS: Eighty-four eligible trials were identified. For the outcomes of all-cause mortality, cardiovascular mortality, fatal or nonfatal myocardial infarction, and blood lipids, neither supplements of vitamin E alone nor vitamin E given with other agents yielded a statistically significant beneficial or adverse pooled relative risk (for example, pooled relative risk of vitamin E alone = 0.96 [95% confidence interval (CI), 0.84 to 1.10]; 0.97 [95% CI, 0.80 to 1.90]; and 0.72 [95% CI, 0.51 to 1.02] for all-cause mortality, cardiovascular mortality, and nonfatal myocardial infarction, respectively. CONCLUSIONS: There is good evidence that vitamin E supplementation does not beneficially or adversely affect cardiovascular outcomes