Optimizing search strategies to identify randomized controlled trials in MEDLINE (original) (raw)
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How to identify randomized controlled trials in MEDLINE: ten years on
Journal of the Medical Library Association Jmla, 2006
OBJECTIVE: The researchers sought to assess whether the widely used 1994 Cochrane Highly Sensitive Search Strategy (HSSS) for randomized controlled trials (RCTs) in MEDLINE could be improved in terms of sensitivity, precision, or parsimony.METHODS: A gold standard of 1,347 RCT records and a comparison group of 2,400 non-trials were randomly selected from MEDLINE. Terms occurring in at least 1% of RCT records were identified. Fifty percent of the RCT and comparison group records were randomly selected, and the ability of the terms to discriminate RCTs from non-trial records was determined using logistic regression. The best performing combinations of terms were tested on the remaining records and in MEDLINE.RESULTS: The best discriminating term was "Clinical Trial" (Publication Type). In years where the Cochrane assessment of MEDLINE records had taken place, the strategies identified few additional unindexed records of trials. In years where Cochrane assessment has yet to take place, "Randomized Controlled Trial" (Publication Type) proved highly sensitive and precise. Adding six more search terms identified further, unindexed trials at reasonable levels of precision and with sensitivity almost equal to the Cochrane HSSS.CONCLUSIONS: Most reports of RCTs in MEDLINE can now be identified easily using "Randomized Controlled Trial" (Publication Type). More sensitive searches can be achieved by a brief strategy, the Centre for Reviews and Dissemination/Cochrane Highly Sensitive Search Strategy (2005 revision).
Journal of Clinical Epidemiology, 2020
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Systematic Reviews, 2016
Background: Previously, we reported on the low recall of Google Scholar (GS) for systematic review (SR) searching. Here, we test our conclusions further in a prospective study by comparing the coverage, recall, and precision of SR search strategies previously performed in Embase, MEDLINE, and GS. Methods: The original search results from Embase and MEDLINE and the first 1000 results of GS for librarianmediated SR searches were recorded. Once the inclusion-exclusion process for the resulting SR was complete, search results from all three databases were screened for the SR's included references. All three databases were then searched post hoc for included references not found in the original search results. Results: We checked 4795 included references from 120 SRs against the original search results. Coverage of GS was high (97.2 %) but marginally lower than Embase and MEDLINE combined (97.5 %). MEDLINE on its own achieved 92.3 % coverage. Total recall of Embase/MEDLINE combined was 81.6 % for all included references, compared to GS at 72.8 % and MEDLINE alone at 72.6 %. However, only 46.4 % of the included references were among the downloadable first 1000 references in GS. When examining data for each SR, the traditional databases' recall was better than GS, even when taking into account included references listed beyond the first 1000 search results. Finally, precision of the first 1000 references of GS is comparable to searches in Embase and MEDLINE combined. Conclusions: Although overall coverage and recall of GS are high for many searches, the database does not achieve full coverage as some researchers found in previous research. Further, being able to view only the first 1000 records in GS severely reduces its recall percentages. If GS would enable the browsing of records beyond the first 1000, its recall would increase but not sufficiently to be used alone in SR searching. Time needed to screen results would also increase considerably. These results support our assertion that neither GS nor one of the other databases investigated, is on its own, an acceptable database to support systematic review searching.
Systematic Reviews, 2013
The Cochrane Collaboration was established in 1993, following the opening of the UK Cochrane Centre in 1992, at a time when searching for studies for inclusion in systematic reviews was not well-developed. Review authors largely conducted their own searches or depended on medical librarians, who often possessed limited awareness and experience of systematic reviews. Guidance on the conduct and reporting of searches was limited. When work began to identify reports of randomized controlled trials (RCTs) for inclusion in Cochrane Reviews in 1992, there were only approximately 20,000 reports indexed as RCTs in MEDLINE and none indexed as RCTs in Embase. No search filters had been developed with the aim of identifying all RCTs in MEDLINE or other major databases. This presented The Cochrane Collaboration with a considerable challenge in identifying relevant studies. Over time, the number of studies indexed as RCTs in the major databases has grown considerably and the Cochrane Central Register of Controlled Trials (CENTRAL) has become the best single source of published controlled trials, with approximately 700,000 records, including records identified by the Collaboration from Embase and MEDLINE. Search filters for various study types, including systematic reviews and the Cochrane Highly Sensitive Search Strategies for RCTs, have been developed. There have been considerable advances in the evidence base for methodological aspects of information retrieval. The Cochrane Handbook for Systematic Reviews of Interventions now provides detailed guidance on the conduct and reporting of searches. Initiatives across The Cochrane Collaboration to improve the quality inter alia of information retrieval include: the recently introduced Methodological Expectations for Cochrane Intervention Reviews (MECIR) programme, which stipulates 'mandatory' and 'highly desirable' standards for various aspects of review conduct and reporting including searching, the development of Standard Training Materials for Cochrane Reviews and work on peer review of electronic search strategies. Almost all Cochrane Review Groups and some Cochrane Centres and Fields now have a Trials Search Coordinator responsible for study identification and medical librarians and other information specialists are increasingly experienced in searching for studies for systematic reviews. Prospective registration of clinical trials is increasing and searching trials registers is now mandatory for Cochrane Reviews, where relevant. Portals such as the WHO International Clinical Trials Registry Platform (ICTRP) are likely to become increasingly attractive, given concerns about the number of trials which may not be registered and/or published. The importance of access to information from regulatory and reimbursement agencies is likely to increase. Cross-database searching, gateways or portals and improved access to full-text databases will impact on how searches are conducted and reported, as will services such as Google Scholar, Scopus and Web of Science. Technologies such as textual analysis, semantic analysis, text mining and data linkage will have a major impact on the search process but efficient and effective updating of reviews may remain a challenge.
Journal of the Medical Library Association, 2022
Objective: The National Library of Medicine (NLM) inaugurated a “publication type” concept to facilitate searches for systematic reviews (SRs). On the other hand, clinical queries (CQs) are validated search strategies designed to retrieve scientifically sound, clinically relevant original and review articles from biomedical literature databases. We compared the retrieval performance of the SR publication type (SR[pt]) against the most sensitive CQ for systematic review articles (CQrs) in PubMed. Methods: We ran date-limited searches of SR[pt] and CQrs to compare the relative yield of articles and SRs, focusing on the differences in retrieval of SRs by SR[pt] but not CQrs (SR[pt] NOT CQrs) and CQrs NOT SR[pt]. Random samples of articles retrieved in each of these comparisons were examined for SRs until a consistent pattern became evident. Results: For SR[pt] NOT CQrs, the yield was relatively low in quantity but rich in quality, with 79% of the articles being SRs. For CQrs NOT SR[pt]...
Analysis of the reporting of search strategies in Cochrane systematic reviews
Journal of the Medical Library Association : JMLA, 2009
Background: The Cochrane Handbook for Systematic Reviews of Interventions provides instructions for documenting a systematic review's electronic database search strategy, listing elements that should be in the description. Complete documentation of the search strategy allows readers to evaluate the search when critically appraising a review's quality. Objective: The research analyzed recently published Cochrane reviews to determine whether instructions for describing electronic database search strategies were being followed. Methods: Eighty-three new reviews added to the Cochrane Database of Systematic Reviews in the first quarter of 2006 were selected for analysis. Eighteen were subsequently excluded because their searches were conducted only in the specialized registers of Cochrane review groups. The remaining sixty-five reviews were analyzed for the seven elements of an electronic database search strategy description listed in the Cochrane Handbook, using dual review with consensus. Results: Of the 65 reviews analyzed, none included all 7 recommended elements. Four reviews (6%) included 6 elements. Thirty-two percent (21/65) included 5 or more elements, with 68% (44/65) including 4 or fewer. Three included only 2 elements. The 65 reviews represented 41 different Cochrane review groups. Conclusion: The instructions from the Cochrane Handbook for reporting search strategies are not being consistently employed by groups producing Cochrane reviews.
International Journal of Epidemiology, 2002
Failure to identify all possibly relevant reports of controlled trials for systematic review could result in bias. As part of the effort to identify all such reports, the Cochrane Collaboration has been using a 'highly sensitive search strategy' developed in 1993 for the retrieval of reports of controlled trials from MEDLINE. Many reviewers do not have access to fee-based versions of MEDLINE and will increasingly turn to the free web-based searching provided by PubMed as a means of identifying reports of controlled trials. Therefore, we set out to revise the original Cochrane strategy to develop a highly sensitive search strategy for the retrieval of reports of controlled trials from MEDLINE using PubMed.
Journal of the Medical Library Association
Objective: The aim of this study was to investigate if the included references in a set of completed systematic reviews are indexed in Ovid MEDLINE and Ovid Embase, and how many references would be missed if we were to constrict our literature searches to one of these sources, or the two databases in combination. Methods: We conducted a cross-sectional study where we searched for each included reference (n = 4,709) in 274 reviews produced by the Norwegian Institute of Public Health to find out if the references were indexed in the respective databases. The data was recorded in an Excel spreadsheet where we calculated the indexing rate. The reviews were sorted into eight categories to see if the indexing rate differs from subject to subject. Results: The indexing rate in MEDLINE (86.6%) was slightly lower than in Embase (88.2%). Without the MEDLINE records in Embase, the indexing rate in Embase was 71.8%. The highest indexing rate was achieved by combining both databases (90.2%). Th...