The use of systematic reviews and meta-analyses in infection control and hospital epidemiology

Systematic review is a type of research that attempts to identify and summarize all of the evidence related to a specific research question. It can be thought of as a "pause" in the process of conducting research in a particular area, in which the following questions are asked: Based on all of the available evidence, what do we know about this specific question so far, and what future studies should be conducted to clarify areas of uncertainty? The systematic review arose as an alternative to the traditional narrative review-which allows authors to pick and choose the studies they discuss and the depth at which they discuss them-a process prone to bias. By adhering to a prospectively defined protocol that specifies how studies should be identified, evaluated, and statistically combined (the statistical process is a component of systematic review and is called "meta-analysis"), systematic reviews reduce the bias inherent to traditional narrative reviews. Systematic reviews are an increasingly common form of published research, and several of the approximately 1000 such studies that are published annually focus on topics important to infection control professionals. Consequently, it is essential that infection control professionals and hospital epidemiologists be able to understand and evaluate the quality of this useful research design. This article discusses the essential elements of a systematic review, provides a framework for evaluating the quality of such an article, and will help the infection control professional and hospital epidemiologist in determining whether the results of such reviews should change clinical practice.