Characteristics and recovery methods of studies falsely excluded during literature screening-a systematic review

Due to the growing need to provide evidence syntheses under time constraints, researchers have begun focusing on the exploration of rapid review methods, which often employ single-reviewer literature screening. However, single-reviewer screening misses, on average, 13% of relevant studies, compared to 3% with dual-reviewer screening. Little guidance exists regarding methods to recover studies falsely excluded during literature screening. Likewise, it is unclear whether specific study characteristics can predict an increased risk of false exclusion. This systematic review aimed to identify supplementary search methods that can be used to recover studies falsely excluded during literature screening. Moreover, it strove to identify study-level predictors that indicate an elevated risk of false exclusions of studies during literature screening.

We performed literature searches for eligible studies in MEDLINE, Science Citation Index Expanded, Social Sciences Citation Index, Current Contents Connect, Embase, Epistemonikos.org, and Information Science & Technology Abstracts from 1999 to June 23, 2020. We searched for gray literature, checked reference lists, and conducted hand searches in two relevant journals and similar article searches current to January 28, 2021. Two investigators independently screened the literature; one investigator performed the data extraction, and a second investigator checked for correctness and completeness. Two reviewers assessed the risk of bias of eligible studies. We synthesized the results narratively.

Three method studies, two with a case-study design and one with a case-series design, met the inclusion criteria. One study reported that all falsely excluded publications (8%) could be recovered through reference list checking compared to other supplementary search methods. No included methods study analyzed the impact of recovered studies on conclusions or meta-analyses. Two studies reported that up to 8% of studies were falsely excluded due to uninformative titles and abstracts, and one study showed that 11% of non-English studies were falsely excluded.

Due to the limited evidence based on two case studies and one case series, we can draw no firm conclusion about the most reliable and most valid method to recover studies falsely excluded during literature screening or about the characteristics that might predict a higher risk of false exclusion.

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