Background: It is unknown whether systematic reviews published in the emergency medicine (EM) literature routinely search gray literature, utilize a hand search for additional studies, address publication bias, and whether they adhere to standardized reporting guidelines. Search strategies, addressing publication bias, and the standardized reporting of systematic review findings can substantially compromise the validity of systematic reviews. We sought to determine whether systematic reviews published in the EM literature frequently include the above comprehensive search strategies and reporting methodologies.
Methods: We searched PubMed to identify all systematic reviews published between January 1st 2017 and December 30th 2018 among the top 5 EM journals according to the Hirsch's h-index, including publications published online ahead of print. All reviews were examined by two authors to confirm that the included studies were systematic reviews. For each included review, the authors extracted the following data points: whether the review searched gray literature, whether a hand search of additional potential studies was employed, whether publication bias was mentioned, whether a clinical trial registry was searched, and whether a systematic review reporting guideline was used.
Results: We identified 132 studies for inclusion. 24 studies were excluded because they were either duplicate publications, clinical policies, or not systematic reviews. Among the 108 systematic reviews included, 53 (49%) searched gray literature, 63 (58%) reported utilizing a hand search for additional references, 36 (33%) searched clinical trial registries, 75 (69%) mentioned publication bias in some way, and 88 (81%) reported an adherence to a systematic review reporting guideline.
Conclusions: Systematic reviews recently published in EM journals do not routinely search gray literature or search clinical trial registries. However, more than half of systematic reviews recently published in the EM literature utilize a hand search for additional references, address publication bias, and adhere to systematic review reporting guidelines. Identification of unpublished clinical trial or gray literature data may improve the validity of EM systematic reviews.