Applications of Meta‐Analysis in Transfusion Medicine

SUMMARy Meta‐analysis, or statistical overview, is the structured and systematic integration of information from different studies of a given problem. When the results are discrepant, the purpose of an overview is to investigate reasons for disagreements among studies. When the results are concordant, the goal of meta‐analysis is to derive, through the application of a number of quantitative techniques, a measure of the effect of an intervention or exposure across the combined investigations. Metaanalysis has been used and misused widely in the medical literature. Readers must develop the skills necessary to comprehend and evaluate published reports of metaanalyses, because health policy guidelines‐and perhaps also recommendations for patient management‐are likely to be increasingly based in the future on input from statistical overviews.