Role of systematic reviews and meta-analysis in evidence-based medicine

The overwhelming increase in the quantity of clinical evidence has led to detachment of the evidence and practice because new evidence can be integrated into clinical practice only after it has been critically appraised and synthesized on the basis of the existing evidence. Because many clinicians lack the skills and the time for such information processing, systematic reviews and meta-analyses, their quantitative counterparts, play an important role in health care. Well performed systematic reviews provide clinically relevant information for surgeons, abrogating the need to identify, read, and evaluate many individual studies. This article reviews the basic principles of meta-analysis, discusses its potential weaknesses such as heterogeneity and publication bias, and highlights special situations when dealing with surgical trials.