RESUMO
Systematic review had become one of the important research area in medicine. Systematic review can be demonstrating benefit or harm of an intervention when results of individual studies are inconclusive. While narrative reviews can often include an element of selection bias, systematic reviews typically involve a comprehensive plan and search strategy with the goal of reducing bias by identifying, appraising, and synthesizing all relevant studies on a particular topic and investigation of heterogeneity among included studies. Systematic reviews typically include a meta-analysis component which involves using statistical techniques to synthesize the data from several studies into a single quantitative estimate or summary effect size. Systematic review overcomes the limitation of small sample sizes by pooling results from a number of individual studies to generate a single best estimate. Although systematic reviews are published in academic forums, the Cochrane Collaboration is a widely recognized international and not-for-profit organization that promotes, supports, and disseminates systematic reviews and meta-analyses on the efficacy of interventions in the health care field. Systematic review has become a popular and powerful tool. If rigorously conducted, it is essential for evidence-based decision making in clinical practice as well as on the health policy level.