A systematic review (SR) aims to retrieve, synthesize, and appraise existing knowledge on a particular subject. Meta-analysis is the statistical method used to combine results from the relevant studies, and the resultant larger sample size provides greater reliability (precision) of the estimates of any treatment effect. Clinical decisions should be based on the totality of the best evidence and not the results of individual studies. The value and credibility of an SR depends on the importance of the question, the quality of the original studies, the efforts undertaken to minimize bias, and the clinical applicability.