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Systematic Reviews Brenda Thomas Information Specialist Cochrane Stroke Group Effective Literature Searching.

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Presentation on theme: "Systematic Reviews Brenda Thomas Information Specialist Cochrane Stroke Group Effective Literature Searching."— Presentation transcript:

1 Systematic Reviews Brenda Thomas Information Specialist Cochrane Stroke Group Effective Literature Searching

2 Stroke Review Group Prepare, keep up to date and disseminate high quality systematic reviews in all aspects of stroke healthcare Comprehensive and versatile register of randomised controlled trials (RCTs) and controlled clinical trials (CCTs)

3 Role of the Trials Search Co-ordinator (TSC)/ Information Specialist Deliver a comprehensive trials identification strategy Deliver a comprehensive trials identification strategy Assess and code relevant stroke trials Assess and code relevant stroke trials Develop and maintain quality and growth of the register of randomised trials and controlled clinical trials Develop and maintain quality and growth of the register of randomised trials and controlled clinical trials Support review authors Support review authors Contribute to the review editorial process Contribute to the review editorial process Considerable time and resources have been committed to maximising trial identification

4 Specialised Register of Stroke Trials As many potentially relevant Randomised Controlled Trials (RCTs) and Controlled Clinical Trials (CCTs) as possible Published trials in any language from any year Published trials in any language from any year Unpublished trials Unpublished trials Ongoing trials Ongoing trials Planned trials Planned trials All the available evidence

5 The Cochrane Stroke Group Trials Register Stroke Group Trials Register is one of the most advanced in the Collaboration All published trial reports included in the Cochrane Central Register of Controlled Trials in The Cochrane Library How we identified stroke trial reports

6 Methods Identify sources of relevant trials Identify sources of relevant trials Develop appropriate search strategies Develop appropriate search strategies Screen bibliographic details for potential reports of trials Screen bibliographic details for potential reports of trials Obtain full copies and apply selection criteria Obtain full copies and apply selection criteria Arrange translation if required Arrange translation if required

7 A systematic approach to trial identification Multiple overlapping search strategies to minimise bias Supported by the considerable resources of The University of Edinburgh and NHS Scotland e-library Electronic databases Electronic databases Handsearching Handsearching Personal communication Personal communication

8 Electronic resources Major medical bibliographic databases Major medical bibliographic databases Eg MEDLINE and EMBASE Eg MEDLINE and EMBASE Topic specific databases Topic specific databases Non-English language databases Non-English language databases International trials and research registers (ongoing trials) International trials and research registers (ongoing trials) The Internet The Internet Regular searches of 27 bibliographic databases Approx 25,000 references screened annually

9 Topic Specific Databases BIOSIS Previews (Biology and pharmacology) BIOSIS Previews (Biology and pharmacology) AMED (Allied and Complementary Medicine) AMED (Allied and Complementary Medicine) CINAHL (Nursing and Allied Health) CINAHL (Nursing and Allied Health) PsycINFO (Psychology) PsycINFO (Psychology) Digital Dissertations (Theses) Digital Dissertations (Theses) MANTIS (Manual, alternative and natural therapy) MANTIS (Manual, alternative and natural therapy) International Pharmaceutical Abstracts International Pharmaceutical Abstracts Occupational Therapy Journal of Research Index Occupational Therapy Journal of Research Index Applied Social Sciences Index and Abstracts Applied Social Sciences Index and Abstracts

10 Clinical Trials Registers bibliographic bibliographic Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library) Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library) The most comprehensive source of reports of controlled trials The most comprehensive source of reports of controlled trials Chinese Clinical Trials Register Chinese Clinical Trials Register The Physiotherapy Evidence Database (PEDro) The Physiotherapy Evidence Database (PEDro) Database of Randomised Controlled Trials in Hyperbaric Medicine (DORCTHIM) Database of Randomised Controlled Trials in Hyperbaric Medicine (DORCTHIM) ongoing ongoing Stroke Trials Directory / Stroke Trials Directory / Current Controlled Trials / Current Controlled Trials / GlaxoSmithKline Clinical Trials Register GlaxoSmithKline Clinical Trials Register RehabTrials.org RehabTrials.org

11 Electronic journals Contents pages and abstracts on-line Contents pages and abstracts on-line Current awareness alerts Current awareness alerts Selected free articles or issues Selected free articles or issues Full text (free or subscribed) Full text (free or subscribed) Download pdfs Download pdfs

12 Personal Communication and The Internet Trialists and colleagues Trialists and colleagues Drug Companies Drug Companies Equipment manufacturers Equipment manufacturers Websites: e.g. company press releases, research centre bulletins, research funders Websites: e.g. company press releases, research centre bulletins, research funders News alerts eg MEDSCAPE News alerts eg MEDSCAPE News media (current awareness) News media (current awareness) Conference abstracts on-line Conference abstracts on-line Essential sources of unpublished and ongoing trials

13 Reference lists Trial reports from publications not indexed in bibliographic databases Trial reports from publications not indexed in bibliographic databases Early trial reports Early trial reports References from grey literature References from grey literature Conference abstracts Conference abstracts books books theses theses

14 Review-specific searches Electronic searches Electronic searches Geographic, eg Chinese Biomedical Literature Geographic, eg Chinese Biomedical Literature Subject specific, Engineering databases Subject specific, Engineering databases Handsearching Handsearching specialist journals and conference proceedings specialist journals and conference proceedings Unpublished studies Unpublished studies Contacting pharmaceutical companies or equipment manufacturers Contacting pharmaceutical companies or equipment manufacturers

15 Key advantage of searching bibliographic databases Can be searched electronically for: Can be searched electronically for: words in the title and abstract words in the title and abstract Standardized indexing terms or controlled vocabulary assigned to each record based on the full report. Standardized indexing terms or controlled vocabulary assigned to each record based on the full report.

16 Limitations and challenges of electronic searching for published studies Selected journals and journal years indexed Selected journals and journal years indexed Conference proceedings and books in selected databases only Conference proceedings and books in selected databases only A complex tailor-made strategy required for each database A complex tailor-made strategy required for each database Poor indexing often limits retrieval Poor indexing often limits retrieval Titles and abstracts (when available) may be insufficiently detailed for text word searching Titles and abstracts (when available) may be insufficiently detailed for text word searching Free-text searching for full-text electronic journals! Free-text searching for full-text electronic journals! High sensitivity searches result in low precision High sensitivity searches result in low precision

17 Handsearching Advantages Advantages All reports of trials in journal All reports of trials in journal Articles, editorials, letters, abstracts, news items Articles, editorials, letters, abstracts, news items Journals, books and conference proceedings not in electronic databases Journals, books and conference proceedings not in electronic databases Recent issues Recent issues Limitations Limitations Time consuming and expensive Time consuming and expensive Large numbers of healthcare journals Large numbers of healthcare journals Access to journals Access to journals Non-English language journals Non-English language journals Subject to human error Subject to human error

18 Is handsearching worthwhile? Complete retrospective search of 32 years of journal STROKE Complete retrospective search of 32 years of journal STROKE Compared with MEDLINE search of STROKE for same publication years Compared with MEDLINE search of STROKE for same publication years MEDLINE search identified 44% of 803 stroke trial reports identified by handsearching. MEDLINE search identified 44% of 803 stroke trial reports identified by handsearching. Conference abstracts and letters etc not indexed by MEDLINE Conference abstracts and letters etc not indexed by MEDLINE Many of the trials published as conference abstracts will not come to full publication Many of the trials published as conference abstracts will not come to full publication

19 Stroke Group general strategy modified for each database STROKE specific strategy Highly sensitive TRIALS strategy Screened for stroke trials ?

20 Review-specific intervention-based strategy STROKE specific strategy Highly sensitive Cochrane TRIALS strategy Review specific INTERVENTION-based strategy Screened for additional relevant trials ? ? ?

21 New developments that make life easier Increasing availability of electronic journals Increasing availability of electronic journals 77% of relevant MEDLINE trial reports in % of relevant MEDLINE trial reports in 2006 Free open access journals and conference proceedings Free open access journals and conference proceedings More detailed reporting of study methods More detailed reporting of study methods Increasing numbers of ongoing trial registers Increasing numbers of ongoing trial registers Including drug company (eg GlaxoSmithKline, Novartis, Roche) Including drug company (eg GlaxoSmithKline, Novartis, Roche) International trial registration International trial registration WHO International Clinical Trials Registry Platform WHO International Clinical Trials Registry Platform Multiple Registers (ISRCTN, NCT, ANZCTR) Multiple Registers (ISRCTN, NCT, ANZCTR) Universal Trial Reference Number Universal Trial Reference Number Easier to track trial reports and link to studies Easier to track trial reports and link to studies

22 Looking for Research Studies? How to search like a professional!

23 Increasing numbers of resources available Need a focused approach using high quality information resources Need a focused approach using high quality information resources Increased use of electronic sources Increased use of electronic sources Efficient search strategies Efficient search strategies

24 Where do we start? Search question? Search question? Purpose of search? Purpose of search? How much information do we need? How much information do we need? Where do we look? Where do we look? How much time do we have? How much time do we have? How much money do we have (if any!)? How much money do we have (if any!)?

25 Sources of Bias Publication bias Publication bias negative results are often not published negative results are often not published “Level of publication” bias “Level of publication” bias abstracts and letters may more often report negative results abstracts and letters may more often report negative results Reference/citation bias Reference/citation bias Cited work is more likely to be positive Cited work is more likely to be positive Electronic database bias? Electronic database bias? Need to search multiple databases Need to search multiple databases Language bias Language bias Aim to minimize bias

26 Bibliographic Databases MEDLINE Major general medical database Major general medical database Indexes articles from >5000 journals (2100 not EMBASE) Indexes articles from >5000 journals (2100 not EMBASE) 37 languages 37 languages >16 million citations from 1950 >16 million citations from 1950 All articles indexed using Medical Subject Headings (MeSH) to describe each article All articles indexed using Medical Subject Headings (MeSH) to describe each article Available on Ovid SP through University or NHS e-Library

27 Bibliographic Databases EMBASE Major general medical database Major general medical database Indexes articles from 4800 journals (1700 not MEDLINE) Indexes articles from 4800 journals (1700 not MEDLINE) 30 languages 30 languages >11 million citations from 1974 >11 million citations from 1974 All articles indexed using Emtree Headings to describe each article (Different from MeSH) All articles indexed using Emtree Headings to describe each article (Different from MeSH) Pharmacological studies indexed in greater depth than MEDLINE Pharmacological studies indexed in greater depth than MEDLINE Available on Ovid SP through University or NHS e-Library Both databases required for a comprehensive search

28 MEDLINE Record searchable fields Authors Authors Title Title Journal title Journal title MeSH Subject Headings MeSH Subject Headings Abstract Abstract Publication Type Publication Type Language Language

29 MEDLINE Developing a Search Strategy Use a combination of MeSH terms and free text for: Use a combination of MeSH terms and free text for: Disease under investigation Disease under investigation Intervention Intervention Study design (methodological filters) Study design (methodological filters) Use “Publication Type” field to focus the type of research (eg randomised controlled trial) Use “Publication Type” field to focus the type of research (eg randomised controlled trial) Apply other logical limiters (eg age group, human, time period) Apply other logical limiters (eg age group, human, time period) Ask your local medical librarian for help!

30 1. cerebrovascular disorders/ or basal ganglia cerebrovascular disease/ or exp brain ischemia/ or carotid artery diseases/ or carotid artery thrombosis/ or intracranial arterial diseases/ or cerebral arterial diseases/ or exp "intracranial embolism and thrombosis"/ or exp stroke/ 2. (isch?emi$ adj6 (stroke$ or apoplex$ or cerebral vasc$ or cerebrovasc$ or cva or attack$)).tw. 3. ((brain or cerebr$ or cerebell$ or vertebrobasil$ or hemispher$ or intracran$ or intracerebral or infratentorial or supratentorial or middle cerebr$ or mca$ or anterior circulation) adj5 (isch?emi$ or infarct$ or thrombo$ or emboli$ or occlus$ or hypoxi$)).tw or 2 or 3 5. cell transplantation/ or stem cell transplantation/ or cord blood stem cell transplantation/ or hematopoietic stem cell transplantation/ or mesenchymal stem cell transplantation/ or peripheral blood stem cell transplantation/ 6. stem cells/ or adult stem cells/ or embryonic stem cells/ or fetal stem cells/ or fibroblasts/ or hematopoietic stem cells/ or myeloid progenitor cells/ or erythroid progenitor cells/ or mesenchymal stem cells/ or multipotent stem cells/ or exp myoblasts/ or pluripotent stem cells/ or totipotent stem cells/ or tumor stem cells/ 7. exp cells/tr 8. ((stem or progenitor or embryo$ or fetal or foetal or umbilical or bone marrow or cord blood) adj5 (cell or cells)).tw. 9. (cell adj5 (transplant$ or graft$)).tw. 10. (fibroblast$ or myoblast$).tw. 11. cell transplantation.jn or 6 or 7 or 8 or 9 or 10 or and limit 13 to humans Stem Cell Transplantation for ischemic stroke MEDLINE (Ovid)

31 Search results Review retrieved citations Review retrieved citations Modify search strategy Modify search strategy New text word terms New text word terms Synonyms, related terms, variant spellings Synonyms, related terms, variant spellings Check MeSH headings Check MeSH headings Check that search strategy identified known references Check that search strategy identified known references Gradually build a comprehensive strategy

32 Features of reference management software Personal reference database Personal reference database organise references organise references create bibliographies create bibliographies Imports references from various databases Imports references from various databases Automatic formatting of papers and bibliographies Automatic formatting of papers and bibliographies Reference Manager, EndNote Reference Manager, EndNote Locally installed or networked Locally installed or networked EUCS provides half-day courses on Reference Manager and EndNote in almost every month of the year EUCS provides half-day courses on Reference Manager and EndNote in almost every month of the year

33 Conclusions Be systematic but realistic! Clearly define search question Clearly define search question Identify relevant available sources Identify relevant available sources Prepare search strategy(ies) Prepare search strategy(ies) Conduct and modify search Conduct and modify search Consider reference management software Consider reference management software Translation? Translation? Correctly document and report the search methods Correctly document and report the search methods

34 Cochrane Handbook for Systematic Reviews of Interventions Chapter 6 Searching for studies Essential Reading Main sources of potential studiesMain sources of potential studies Planning the search processPlanning the search process Designing and carrying out the search strategiesDesigning and carrying out the search strategies Managing referencesManaging references Correctly documenting and reporting the search processCorrectly documenting and reporting the search process


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