Comparison of information sources used in Cochrane and non-Cochrane systematic reviews: A case study in the field of anesthesiology and pain.

Abstract

It has been reported that information sources searched in systematic reviews (SRs) are insufficiently comprehensive. We analyzed information sources used in SRs, as well as how up-to-date were the searches. We searched PubMed and the Cochrane Database of Systematic Reviews (CDSR) through Wiley from 2012 to 2016 to find SRs of randomized controlled trials (RCTs) in the field of anesthesiology and pain. We analyzed information sources used and search dates. We analyzed 674 SRs, including 374 non-Cochrane SRs (NCSRs) and 300 Cochrane reviews. The most commonly searched electronic databases reported in all included SRs were Embase (88.6%), MEDLINE (78.3%), CENTRAL (76.1%), CINAHL (29.1%), and PubMed (30.9%). In 303 (45%) SRs, authors reported that they searched clinical trial registries; 57 (8.5%) reported that they searched for unpublished data, 184 (27.3%) searched grey literature, 51 (7.6%) searched citations, and 546 (81%) searched references of included studies. A substantial amount of Cochrane reviews searched clinical trial registries (75.7%), compared with NCSRs (20.3%). Search date was reported in 647 SRs (96.1%). The median time between the last search date and publication for the SRs that reported search date was 10 months. For the NCSRs, median time between the last search and publication date was significantly higher compared with Cochrane reviews. Nonreporting of search date was more prevalent in NCSRs. SRs in the field of anesthesiology and pain often neglect to search all possible information sources, particularly in NCSRs. Cochrane reviews had more comprehensive searching and shorter search to publication time.