Systematic reviews in emergency medicine: Part II. Critical appraisal of review quality, data synthesis and result interpretation.

Reviews of the medical literature have always been an important resource for physicians. Increasingly, qualitative and quantitative systematic reviews (SRs) have replaced the traditional "narrative review" as a means of capturing and summarizing current evidence on a topic or, when possible, answering a specific clinical question. This paper is Part II of a 2-part series designed to provide emergency physicians with the background necessary to locate, critically evaluate and interpret SRs. The paper expands on the critical appraisal principles discussed in Part I by focusing on quality assessment, data synthesis and interpretation of results. To illustrate key points and facilitate readability, examples from the emergency medicine literature have been included and technical details have been kept to a minimum. The references, however, are comprehensive and provide a resource for readers seeking further information.