Basics of meta-analysis.

Meta-analysis is an approach to formally, systematically and quantitatively analyze multiple existing research studies and to synthesize new research findings based upon the existing data. Until the late 1970s, meta-analyses were not regularly reported in the medical literature, but since then there has been an exponential growth of meta-analyses and they are now among the most frequently cited form of research. A properly performed systematic review and meta-analysis is a very important tool in evidence-based medicine and a good understanding of the steps involved in doing a systematic review and meta-analysis is important to yield meaningful results. The purpose of this review article is to provide a brief overview about systematic reviews and meta-analyses and the underlying principles for conducting this type of research. Methodological approaches for conducting a meticulous meta-analysis are described and the important steps involved in the interpretation and presentation of meta-analysis are outlined and discussed. The key objective of this paper is to outline a step-by-step approach that is useful to all researchers, who would like to conduct their first meta-analysis. This paper also provides clinicians and researchers with the information to interpret systematic reviews and meta-analyses.