Interpretation of meta-analyses.

Our article provides guidance on how to interpret a meta-analysis and introduces the reader to the basics of the underlying statistical analysis. The multiple steps of a meta-analysis including systematic literature search, risk of bias assessment, data extraction and data aggregation are addressed. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach allows to score the quality of the evidence of the results revealed by a meta-analysis. Trial sequential analysis has been suggested in recent years as a method to assess the power of a meta-analysis and the risks of false positive or false negative conclusions. We also provide information on other more complex meta-analytical approaches including network meta-analysis for the comparison of several treatments as well as recent developments such as individual patient data meta-analysis and living meta-analysis.