title: Design and implementation of Metta, a metasearch engine for biomedical literature retrieval intended for systematic reviewers.
abstract: BACKGROUND
  Individuals and groups who write systematic reviews and meta-analyses in evidence-based medicine regularly carry out literature searches across multiple search engines linked to different bibliographic databases, and thus have an urgent need for a suitable metasearch engine to save time spent on repeated searches and to remove duplicate publications from initial consideration. Unlike general users who generally carry out searches to find a few highly relevant (or highly recent) articles, systematic reviewers seek to obtain a comprehensive set of articles on a given topic, satisfying specific criteria. This creates special requirements and challenges for metasearch engine design and implementation.
  
  
  METHODS
  We created a federated search tool that is connected to five databases: PubMed, EMBASE, CINAHL, PsycINFO, and the Cochrane Central Register of Controlled Trials. Retrieved bibliographic records were shown online; optionally, results could be de-duplicated and exported in both BibTex and XML format.
  
  
  RESULTS
  The query interface was extensively modified in response to feedback from users within our team. Besides a general search track and one focused on human-related articles, we also added search tracks optimized to identify case reports and systematic reviews. Although users could modify preset search options, they were rarely if ever altered in practice. Up to several thousand retrieved records could be exported within a few minutes. De-duplication of records returned from multiple databases was carried out in a prioritized fashion that favored retaining citations returned from PubMed.
  
  
  CONCLUSIONS
  Systematic reviewers are used to formulating complex queries using strategies and search tags that are specific for individual databases. Metta offers a different approach that may save substantial time but which requires modification of current search strategies and better indexing of randomized controlled trial articles. We envision Metta as one piece of a multi-tool pipeline that will assist systematic reviewers in retrieving, filtering and assessing publications. As such, Metta may find wide utility for anyone who is carrying out a comprehensive search of the biomedical literature.
authors.affiliation: Department of Psychiatry and Psychiatric Institute, University of Illinois at Chicago, Chicago, IL 60612 USA.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Smalheiser
authors.affiliation: Department of Computer Science, Binghamton University, Binghamton, NY USA.
authors.forename: Can
authors.initials: C
authors.lastname: Lin
authors.affiliation: Department of Computer Science, University of Illinois at Chicago, Chicago, IL 60612 USA.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Jia
authors.affiliation: Department of Computer Science, Binghamton University, Binghamton, NY USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University, Portland, OR USA.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Cohen
authors.affiliation: Department of Computer Science, University of Illinois at Chicago, Chicago, IL 60612 USA.
authors.forename: Clement
authors.initials: C
authors.lastname: Yu
authors.affiliation: Department of Psychiatry and Psychiatric Institute, University of Illinois at Chicago, Chicago, IL 60612 USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Davis
authors.affiliation: Division of Psychiatry, University of Nottingham, Nottingham, UK.
authors.forename: Clive E
authors.initials: CE
authors.lastname: Adams
authors.affiliation: Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University, Portland, OR USA.
authors.forename: Marian S
authors.initials: MS
authors.lastname: McDonagh
authors.affiliation: Department of Computer Science, Binghamton University, Binghamton, NY USA.
authors.forename: Weiyi
authors.initials: W
authors.lastname: Meng
keywords: Bibliometrics; Evidence-based medicine; Information retrieval; Medical informatics; Meta-analysis; Metasearch engine; Systematic reviews
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