What is the difference between a systematic review and a meta-analysis?

Abstract

Distinguishing between a systematic review and meta-analysis is essential to understand the role each plays in presenting and analysing data and estimates of treatment effects. Often, novice researchers mistakenly use these terms synonymously. A thorough understanding of the similarities and differences between these two research methodologies is needed to appropriately evaluate the quality of conclusions emerging from such studies. The systematic review allows the researcher to synthesize and critically appraise a number of studies in a specific context to provide evidence-based conclusions. Comparatively, atop the hierarchical chain of evidence lies the meta-analysis, in which a systematic review is performed and then statistical methods are employed to quantitatively pool the results of a selected number of studies in a specific context. This design is a robust method of combined analysis and is therefore deemed the highest level of evidence when pooling high-quality randomized controlled trials. Understanding and appreciating the methodological differences in these two designs are elemental in planning, implementing, and evaluating high-quality research.