We have read with great interest the critical care review by Kreider and Lipson (July 2003)1–
concerning bronchoscopy for atelectasis in the ICU. However, the authors used a single method of locating review articles, including only MEDLINE, and excluded other electronic databases. Currently, such a restricted search is generally not considered adequate. Studies2–
have shown that only 30 to 80% of all known published randomized, controlled trials were identifiable using MEDLINE (depending on the area or specific question). A comprehensive search is important not only for ensuring that as many studies as possible are identified, but also to minimize any selection bias for those that are found. Relying exclusively on a MEDLINE search may retrieve a set of reports unrepresentative of all reports that would have been identified through a comprehensive search of several sources.3
To prevent bias and to ensure that all relevant data are included in a review, it is fundamental to use multiple sources such as EMBASE, Best Evidence, and the Cochrane Library to identify studies and then to use a systematic approach5
to select those that will be included.