Examining the evidence in anesthesia literature: a critical appraisal of systematic reviews.

Systematic reviews are structured reviews that use scientific strategies to reduce bias in the collection, appraisal, and interpretation of relevant studies. We undertook a systematic review of published systematic reviews in perioperative medicine to summarize the areas currently covered by this type of literature, to evaluate the quality of systematic reviews in this field, and to assess some of the methodologic and reporting issues that are unique to systematic reviews. Computerized bibliographic databases, citation review, and hand searches were performed to identify eligible articles. Quality was assessed using the Overview Quality Assessment Questionnaire. Eight-two systematic reviews were found. Reviews in perioperative medicine tended to evaluate prophylactic or therapeutic interventions. No differences were seen in quality between reviews published in anesthesia and nonanesthesia journals. Nearly half of all systematic reviews had only minor or minimal flaws; however, methods can be improved with expanded search strategies, use of least two reviewers to assess each study, use of validated methods to evaluate quality, and assessment of potential sources of bias.