How to use a systematic literature review and meta-analysis

Bhandari M, Devereaux PJ, Montori V et al. Users’ guide to the surgical literature: how to use a systematic literature review and meta-analysis. Can J Surg. 2004;47(1):60-7. PMID:14997929.

Abstract

An evidence-based approach to surgery incorporates patients’ circumstances or predicaments, identifies knowledge gaps and frames questions to fill those gaps, conducts efficient literature searches, critically appraises the research evidence and applies that evidence to patient care. The practice of evidence-based medicine, therefore, is a process of lifelong self-directed learning in which caring for patients creates a need for clinically important information about diagnoses, prognoses, treatments and other health care issues.

Readers are able to utilize several types of summarized information from expert opinion and textbook reviews to systematic reviews. Traditional, or narrative, reviews, by definition, do not use a systematic approach to identifying information on a particular topic. Moreover, narrative reviews often pose background-type questions and provide a general overview of a topic such as those found in book chapters and instructional course lectures. A background question is, for example, “What is the epidemiology, clinical presentation, treatment options and prognosis following femoral shaft fractures in adults?” We use the term systematic review for any summary of the medical literature that attempts to address a focused clinical question with explicit strategies for the identification and appraisal of the available literature; meta-analysis is a term used for systematic reviews that use quantitative methods (i.e., statistical techniques) to summarize the results. Systematic reviews typically pose a foreground-type question. Foreground questions are more specific and provide insight into a particular aspect of management. For instance, investigators may provide a systematic review of plating versus nailing of humeral shaft fractures on nonunion rates (foreground question) rather than a general review of how bone heals after all treatments of humeral shaft fractures (background question).

Whereas systematic reviews (and meta-analyses) have become popular in surgery, they are not without limitations. The quality of the systematic review is influenced by the quality of the primary studies being reviewed. However, in the absence of large, definitive clinical trials, meta-analyses can provide important information to guide patient care as well as future clinical research.

In applying the suggested guidelines you will gain a clear understanding of the process of conducting a systematic review.

The conduct and interpretation of systematic reviews in surgery is often challenging given the paucity of clinical trial available on any given topic. However, if investigators adhere to proper methodology, they can provide conclusions drawn from a comprehensive study with limited bias.

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