Literature Searching

Pawin Numthavaj M.D.

Section for Clinical Epidemiology and Biostatistics

Faculty of Medicine, Ramathibodi Hospital, Mahidol University

Bangkok, Thailand

www.ceb-rama.org

Literature searching

•Needed for every study before study conduction

•Provide the knowledge of “Gap of information”

•Why should you do your research

•Conducting a systematic review recommended

Study Identification Process

Select Database(s) to Use

Develop Search Strategy

Searching

Explore Results from Searching

Export into Reference Manager

ModifySearch Strategy

DatabaseJournal Articles Databases

• MEDLINE

• EMBASE

• SCOPUS

• Cochrane databases

• DARE (Database of Abstracts of Reviews of Effects)

• Web of Science

• CINAHL

• PsycINFO

• Etc.

Grey Literature

• Organization reports

• Governmental reports

• Conference Proceedings

• Dissertation & Theses

• Web

Multiple Databases

MEDLINE

EMBASECINAHL

Research Question

•P Patient

• I Intervention

•C Comparison

•O Outcome

PBell Palsy

Idiopathic Facial Palsy

I

Antiviral

Acyclovir

Valacyclovir

Steroid

Prednisolone

Methylprednisolone

C Steroid

Prednisolone

Methylprednisolone

O

Recovery Rate

House-Brackmann Scale

Sunnybrook Scale

AND

AND

AND

Group Your Question into Terms

•Terms #1 Antiviral• Subject Headings “Antiviral agents”• Text words “Antivirus”, “Antiviral drug”, …

•Terms #2 Steroid• Subject Headings “Steroids”• Text words “Steroid”, “Prednisolone”, …

•Terms #3 Bell Palsy• Subject Headings “Bell Palsy”

• Text words “Bell Palsy”, “Idiopathic facialparalysis”, …

Combination of Search Terms

•Use “AND” between domains (P/I/C/O)

•Use “OR” inside domains for similar terms or terms that have several synonyms

•Try to use “keyword searching”

Subject Headings

Database Subject Headings

MEDLINE MeSH

EMBASE EMTREE

CINAHL CINAHL Headings

Cochrane Library MESH

PsycINFO Thesaurus of Psychological Index Terms

SCOPUS N/A

Web of Science N/A

Search Engine and Database

Search Engine Database(s)

PubMed MEDLINE

Ovid MEDLINE, EMBASE, …

Scopus SCOPUS

PubMed Searching

PubMed

•Free search engine

•Comprises of MEDLINE database

•Maintain by US National Library of Medicine, National Institutes of Health

•First released in 1996

•Accessed from “http://www.pubmed.gov”

MEDLINE

•1946 to present material

•5,600 journals in 39 languages

•2,000 - 4,000 references added each day

•Biomedicine and health

Frequently Used Functions in PubMed

1. MESH

2. Search Operators

3. Limits

4. Clipboard

5. Save searches

6. Advanced search

7. Citation matcher

8. Clinical Queries

9. Retrieval of full text paper

MESH

•Medical Subject Heading

•Keyword system in Medline

Search Operators

•Truncated search term (wildcards)• flavor* = flavoring + flavored + flavors• synerchi* = synerchiae + synerchia

•Combining search terms• AND• OR• NOT• ( )

Limits

•Filter unwanted results• Age: infants, adults, …• Article types: original

studies, RCTs, Meta-analysis, …

• Article language

• Human/animal• Recently published

Clipboard

•Stored items for later review

•Max 500 items

•8 hours before deleted

•Send to ‘collection’ instead if you want to permanently stored

• (Need My NCBI account)

Saved search

•Save for later updates

•Useful when you’re doing systematic review

•Can also automatically e-mail updates

Advanced Search

•Search in command line-based

•Useful for complex searches

•Use # for referring to previous searches

•Operators: AND, OR, NOT, and ()

Download History

•CSV File

•Open in Spreadsheet programs (Excel)

•For use in report of search strategy supplementary table

Export to EndNote

Export to EndNote

•Send To command

•File• Choose MEDLINE• In EndNote choose

PubMed (NLM)

•Citation manager• .nbib EndNote• Limit 200 article

maximum

Citation Matcher

• Locate an article when you know the author name / title / journal name / volume / pages

•http://www.ncbi.nlm.nih.gov/pubmed/citmatchor visit pubmed.gov and look for Single Citation Matcher

Example

•Try to find this article from PubMed

•REFERENCE: "Itch Relief by Mirror Scratching. A Psychophysical Study," Christoph Helmchen, Carina Palzer, Thomas F. Münte, Silke Anders, Andreas Sprenger, PLoS ONE, vol. 8, no 12, December 26, 2013, e82756.

Clinical Queries

• “Filter” for specific area of question

•Etiology•Diagnosis•Therapy•Prognosis•Clinical Prediction

Guides•Systematic Review

Category Optimized ForSensitive/

SpecificPubMed Equivalent

therapysensitive/broad 99%/70%

((clinical[Title/Abstract] AND trial[Title/Abstract]) OR clinical trials[MeSH Terms] OR clinical trial[Publication Type] OR random*[Title/Abstract] OR random

allocation[MeSH Terms] OR therapeutic use[MeSH Subheading])

specific/narrow 93%/97% (randomized controlled trial[Publication Type] OR (randomized[Title/Abstract] AND controlled[Title/Abstract] AND trial[Title/Abstract]))

diagnosissensitive/broad 98%/74%

(sensitiv*[Title/Abstract] OR sensitivity and specificity[MeSH Terms] OR diagnos*[Title/Abstract] OR diagnosis[MeSH:noexp] OR diagnostic *

[MeSH:noexp] OR diagnosis,differential[MeSH:noexp] OR diagnosis[Subheading:noexp])

specific/narrow 64%/98% (specificity[Title/Abstract])

etiology

sensitive/broad 93%/63% (risk*[Title/Abstract] OR risk*[MeSH:noexp] OR risk *[MeSH:noexp] OR cohort studies[MeSH Terms] OR group*[Text Word])

specific/narrow 51%/95%((relative[Title/Abstract] AND risk*[Title/Abstract]) OR (relative risk[Text Word]) OR risks[Text Word] OR cohort studies[MeSH:noexp] OR (cohort[Title/Abstract]

AND stud*[Title/Abstract]))

prognosissensitive/broad 90%/80%

(incidence[MeSH:noexp] OR mortality[MeSH Terms] OR follow up studies[MeSH:noexp] OR prognos*[Text Word] OR predict*[Text Word] OR

course*[Text Word])

specific/narrow 52%/94% (prognos*[Title/Abstract] OR (first[Title/Abstract] AND episode[Title/Abstract]) OR cohort[Title/Abstract])

clinical prediction

guides

sensitive/broad 96%/79% (predict*[tiab] OR predictive value of tests[mh] OR scor*[tiab] OR observ*[tiab] OR observer variation[mh])

specific/narrow 54%/99% (validation[tiab] OR validate[tiab]