Systematic Review and Meta-Analysis: pearls for interpretation, appraisal and application in clinical practice

Systematic reviews (SR) are a category of literature review that presents a comprehensive synthesis and analysis of all available literature evidence addressing a specific clinical question. Meta-analysis (MA) is a quantitative technique that is applied to data collected through SR that provides an estimate of an effect across a larger population. By synthesizing data from a large number of sources SR and MA often provide insights that cannot be obtained from single studies and can aid in clinical decision-making. However, these techniques are subject to important limitations. Both the validity and the usefulness of the results of an SR/MA depend on the methodological rigor used in preparing the review and the quality of included studies. In applying SR/MA to clinical decision-making the reader should be able to assess these features. Here we present an overview of important concepts in understanding SR and MA. We provide a general approach to interpretation and evaluation of an SR/MA, model the use of a critical appraisal tool for SR, and discuss the applications of SR and MA to clinical practice.