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Disc laimer: The contents of this presentation are the views of the author and do not necessarily represent an offic ial position of the European C ommission. © European Union, 2013
Search of the literature
Theodora Mouratidou and Carlos Martin Saborido
Public Health Policy Support Unit
Institute for Health and Consumer Protection
(JRC-IHCP)
2 GRADE Workshop – Ispra– 11-12 December 2013
GRADE Workshop: Agenda
9:00 - 10:15 Introduction. Guideline development process and the GRADE approach
10:15-11:00 Types of questions. Framing a question: PICO question. Exercise
11:00-11:15 Coffee
11:15-12:00 Choosing outcomes. Relative importance of outcomes. Exercise
12:00-12:45 Study designs. Exercise
12:45-13:30 Lunch
13:30-14:30 Search of the literature. Exercise
14:30-15:00 Determinants of quality of evidence: What can lower the evidence? (I)
15:00-15:15 Coffee
15:15-17:00 Determinants of quality of evidence: What can lower the evidence? (II) Exercise
9:00-11:15 Determinants of quality of evidence: What can lower the evidence? (III)Determinants of quality of evidence: What can upgrade evidence?
11:15-11:30 Coffee
11:30-13:00 Going from the evidence to the recommendation. Exercise
13:00-13:45 Lunch
13:45-16:00 Using the Guideline Development Tool (GDT) software. ExerciseFeedback and conclusions
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a. Introduction
b. Search evidence in Medline
c. Search evidence beyond Medline
d. Other sources of evidence
e. Practical exercise
Outline
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• Databases used will depend on a number of factors including the
research question, the study design of studies to be included as well as
on your resources!
– RCTs: Medline, Central, EMBASE
– Systematic Reviews: Medline, CDSR, EMBASE, DARE
– Health Technology Assessment: HTA database + websites
– Guidelines: Medline, NGC, GIN, websites
– Diagnostic tests: Medion
– Nursing aspects: Cinahl
Searching where?
5 GRADE Workshop – Ispra– 11-12 December 2013
• PubMed Central (PMC) is the National Library of Medicine's digital
archive of full-text journal literature
– > 6000 journals, 20 millions articles
– Free of charge
– 65% RCTs
– US-based, biased towards english (91%)
• http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed
Medline
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– How is the the MeSH used
– Search strategy
– Managing results
– Saving search strategies
– Getting the articles
Searching MEDLINE
……….a specific set of terms used to describe each article……………
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• Balance between sensitivity (attempts to retrieve all relevant documents
by using a broad search) and specificity (attempts to retrieve only
relevant documents in a small precise search). A happy medium is
desirable!
• Boolean logic (allow you to broaden or focus your search results)
x AND (y OR z) will retrieve records that contain the term x, as well as one
or both of the terms y OR z
Search strategy
AND OR NOT
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• Articles are indexed using a powerful vocabulary called MeSH
• The MeSH Database provides the option of identifying appropriate MeSH
terms for searches
• Represent concepts found in the biomedical literature arranged in a
hierarchical manner called the MeSH Tree Structure (16 main branches)
• > 25000 MeSH descriptors
• > 172000 ‘entry terms’
• MeSH terms are "exploded" automatically to retrieve citations that carry
the specified MeSH (sub) heading and also retrieve citations that carry
any of the more specific MeSH (sub) headings indented beneath it in the
Tree structure.
Medical Subject Headings (MeSH)
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• Medline indexers assign the most specific MeSH heading(s) appropriate
to describe the main concepts discussed (or the closest one)
• Generally 5 to 15 MeSH
• MeSH terms reflecting the major points of the article are marked with an
asterisk (*)
• Information the indexer provides includes:
� topic of article
� age group of population studied
� human vs. animal studies
� type of article (e.g., review article)
MeSH
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• The MeSH Database allows you to:
� Locate and select MeSH terms, (Headings, Subheadings, &
Publication Types); Supplementary Concept terms (Substance
Names) and Pharmacological Action terms
� See the definition and other helpful information for a MeSH term
� Build a PubMed search strategy
� Display MeSH terms in the hierarchy
� Limit MeSH terms to a major concept for a search
� Attach subheadings for a search
� Link to the NLM MeSH Section's MeSH Browser
• Not all databases allow MeSH searches! And searching with MeSHheadings will exclude in process and publisher-supplied citations, as theyare not indexed with MeSH
MeSH database
http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_490.html
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• PubMed automatically searches for phrases during Automatic TermMapping (ATM)-process to find a match to unqualified terms that areentered into the query box
• If you want to force a phrase search, you can do so by:
• Enclosing the phrase in double quotes:"fecal transplant"
Note: The absence of a search tag indicates the search should be conductedin All Fields
• Entering the phrase with a search tag:robotic surgery[tw]
• Hyphenating:first-line
• Truncating:citizen jur*
Phrase Searching
http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_440.html
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• Using quotes, search tags, hyphenation or truncation instructs PubMed to
bypass ATM. Instead PubMed looks for the phrase in its Index of
searchable terms. If the phrase is in the Index, PubMed will retrieve
citations that contain the phrase
• PubMed may fail to find a phrase because it is not in the Index
• Your phrase may actually appear in citation and abstract data, but may
not be in the Index. If this is the case, the double quotes are ignored and
the phrase is processed using Automatic Term Mapping
http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_440.html
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• Truncation: search method in which symbols are used in place of letters
or words to broaden search
- Asterisk (*)
e.g. Medic*: “medical” or “medicine”
- Question mark (?)
e.g. Analys?s: retrieve “Analysis” y “Analyses”
e.g. Meta?analysis: retrieve “metaanalysis” AND “ meta-
analysis”
• Truncation turns off mapping on both unqualified or qualified terms.
Truncation terms (*,?)
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• Is available on the Advanced Search page showing your searchstrategies and number of items found for each search
• Can hold a maximum of 100 search statements
– The History screen displays:
• Your search query
• Most recent 5 searches are displayed
• The time of the search
• The number of citations in your search results
• Search statement numbers menu for combining searches
– The search history is deleted after 8 hours of inactivity
– If a search is repeated, its original number is moved to the top
PubMed Search History
http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_400.html
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• My NCBI (personal account ; password required)
– Searches: save search strategies to get updates,including automatic e-mail updates
– Collections: save search results
– My Bibliography: collect citations for your publications
Managing results
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• Links to full text resources from PubMed are available through a service
called LinkOut
Getting the articles
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• Europe-based
• > 24 million references
• +/- 7500 journals (>2000 non-Medline)
• Pharmacological journals!
• http://www.info.embase.com/
• EMTREE contains all MeSH terms as used in Medline (many as
synonyms)
– > 56000 ‘controlled descriptors’ (preferred terms)
– > 230000 synonyms (i.e. guides to preferred terms)
EMBASE
20 GRADE Workshop – Ispra– 11-12 December 2013
• Cochrane Database of Systematic Reviews, CDSR
• Database of Abstracts of Reviews of Effects, DARE
• Cochrane Central Register of Controlled Trials
=CENTRAL
• Cochrane Methodology Register, CMR
• Health Technology Assessment Database
• NHS Economic Evaluation Database
• http://www.thecochranelibrary.com/view/0/index.html
Cochrane Library
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• Centre for Reviews and Dissemination, University of
York:http://www.crd.york.ac.uk/crdweb/
• PEDro: http://www.pedro.org.au/
• Cinahl: http://www.ebscohost.com/cinahl/
• Medion: http://www.mediondatabase.nl/
• PsycInfo: http://www.apa.org/pubs/databases/psycinfo/index.aspx
• National Guideline Clearinghouse: www.guidelines.gov
• Guidelines International Network: www.g-i-n.net
• SUMSearch: http://sumsearch.uthscsa.edu/
• TRIP Database: http://www.tripdatabase.com/
• Citation Indexes (e.g. ISI Web of Knowledge)
Other databases
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• Public Health Interventions Cost Effectiveness Database (PHICED):
http://www.yhpho.org.uk/nphl/nphlresults.asp
• Database of Promoting Health Effectiveness Reviews (DoPHER):
http://eppi.ioe.ac.uk/webdatabases/Intro.aspx?ID=2
• Canadian Institutes of Health Research (CIHR): http://health-
evidence.ca/articles/search
• Public Health + (National Collaborating Centre for Methods and Tools,
NCCMT): http://www.nccmt.ca/tools/public_health_plus-eng.html
• And others………
Specific public health sources
23 GRADE Workshop – Ispra– 11-12 December 2013
• http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_490.html
• http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_440.html
• http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_400.html
Links
Any questions?
Next:Exercise
JRC xxxxx – © European Union, 2013Disc laimer: The contents of this presentation are the views of the author and do not necessarily represent an offic ial position of the European C ommission.
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Take home example
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