Identifying and Removing Duplicate Records Resultant from Systematic Review Searches: a Comparative Investigation

Background: Strategies for deduplicating records returned from systematic review searches remain mostly an informal skill discussed on search expert listservs. The purpose of this study was to formally compare the effectiveness of different options for deduplicating records returned from systematic review searches. Methods: Five deduplication options were compared in this study using the records from a published systematic review: deduplication in Ovid across Embase and MEDLINE records (Ovid multifile search), deduplication of MEDLINE records in Ebsco CINAHL, and deduplication of MEDLINE, Embase, and CINAHL records in RefWorks, EndNote, and Mendeley. The time taken to deduplicate in each option and the number of false positives (duplicate citations that were deleted but should not have been) and false negatives (duplicate citations that should have been deleted but were not) resultant from each option were recorded. Results: Except for deduplication of records in RefWorks, which took 10 min, each deduplication option took less than three minutes to execute. The number of false positive and negatives for each option varied, with only the OVID multifile search resulting in zero false positives. Discussion: Based on the results of this study, we recommend different deduplication options based on the skill level of the searcher and the purpose of deduplication efforts.