Can database-level medline exclusion filters in embase and cinahl be used to remove duplicate records without loss of relevant studies in systematic reviews? An exploratory study

Abstract

Objective: To investigate whether using database filters to remove MEDLINE results within Embase (OVID) and CINAHL (EBSCO) would result in fewer duplicate records, without leading to any loss of studies included in the final review.Methods: We reviewed the included studies from a sample set of 20 Cochrane Reviews published in 2015-2018, and replicated the search strategies from those reviews in MEDLINE, EMBASE (both on the OVID platform) and CINAHL (EBSCO). Results were exported to EndNote; then relevant MEDLINE filters were applied within CINAHL and Embase, and results were exported again. Filtered results were analysed to determine whether the filtered EMBASE and CINAHL results excluded studies that were not identified in the original MEDLINE search. Results: Using the “Records from: Embase” filter resulted in no loss of included studies; however, the “Exclude MEDLINE journals” filter in Embase resulted in a failure to retrieve a large number of relevant studies. CINAHL’s filter for MEDLINE records resulted in a small number of studies being lost. Conclusions: The “Records from: Embase” filter may be safely used for deduplication, though as it removes conferences, searchers may also want to review Conference abstracts separately using the Conferences filter. CINAHL’s MEDLINE filter comes with a small risk of filtering out relevant studies, but may be appropriate to use. Although we did not set out to address this issue, our results demonstrate that searches of MEDLINE are still necessary, as not all relevant results were found in Embase alone in order to identify all relevant studies.