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MEDICAL LITERATURE SEARCHING / RETRIEVAL
Chapter 2
Dr. saroj suwal
OBJECTIVES What is medical literature search Why search For whom search Steps in searching Quality searching
WHAT IS MEDICAL LITERATURE SEARCH OR RET RIVAL
an activity that uses professional methods for medical research papers retrieval, report and other data to improve medicine research and practice.
Literature search:Right path to the right reference
WHY SEARCH
For writing thesis,review ,jornals ,reports etc For working as a research assistant For finding funding proposal or grant
application For academic work as a faculty member For working as a professional researcher
WHY MEDICAL LITERATURE RETRIEVAL/SEARCH
Searching the literature is an essential component of the scholarly research process to conduct a quality literature search crucial for
academic study and professional development to create and publish secondary analysis on a
specific topic, for analysis of original research, to be able to locate the best evidence to
answer clinical questions
OVERALL STRUCTURE OF SEARCHING
Broad search question
specificvSearch results
RelevantSearch results
Your specific search resutl
LEVEL OF EVIDENCE PYRAMID
Qualitative Studies
SAMPLE SEARCH STATEMENTS Searchosteoarthritis of the knee.
13,886 articles in PubMed
Search RCTs on arthroscopic surgery for osteoarthritis of the knee that include placebo surgery as a control.
9 articles in PubMed
SearchRCTs on arthroscopic surgery conducted in latino females with type 1 diabetes mellitus.
0 articles in PubMed
7 STEPS IN A COMPREHENSIVE SEARCH
1. Develop a search statement or question2. Select a source 3. Choose search terms4. Run the search5. Apply practical screens (limits)6. Apply methodological screens7. Synthesize the results
MOST RESEARCH QUESTIONS ARE TOO BROAD AT FIRST. THE NARROWER
THE FOCUS, THE EASIER THE QUESTION IS TO RESEARCH
WHY?To guide your reviewTo provide you with keywords for your
searchTo give your research precision
1. Developing search questions
GOOD SEARCH QUESTIONS
CHARACTERISTICS OF A
GOOD STUDY QUESTION“FINER”
F= FeasibleI= InterestingN= NovelE= EthicalR= Relevant
QUESTIONSBroad:
• What is the prevalence of hypertension in patients with diabetes mellitus?
Narrow:
• Does ambulatory BP readings improve detection rates for hypertension in
patients with type 1 diabetes mellitus?
Very Narrow:
• What are the attitudes of general practitioners in south china to the
use of ambulatory BP readings for patients with type 1 diabetes mellitus?
HOW QUESTIONS INFLUENCE SEARCH RESULTS
Relevancy
Retrieval(# of search results)
Broad Questions
Narrow Questions
High = lots of articles
Low = very few articles
High = directly relevant articles
Low = mostly irrelevant articles
HOW TO NARROW SEARCH TOPIC
ASKING “THE QUESTION”The PICO format:
P PopulationI Intervention or Interest areaC Comparison intervention or statusO Outcome
SOURCES OF MEDICAL LITERATURES Internet Websites, search engines, news & alert
services The Library
Look through the list of journals and browse the text books on the shelves to find relevant ones
Digital Libraries Need to use keyword searches to identify relevant
articles
Newspaper and magazines Text books, Guidelines, Factsheets,
Databases, Reports
Primary Source-original journals
Secondary Source –review articles
Tertiary Source-text books
Web Sites can be very good for finding quality information
including primary sources, statistical information and many more
rigorously evaluate each site for quality and responsibility
Because anyone can post a Web page, regardless of their expertise or intentions.
Use keyword searches in Google (which indexes PDF and PostScript academic publications)
Search EnginesGeneral Web search engines :
Google, AllTheWeb and Yahoo,baidu, altavista….
For research covered only in unpublished reports or news items, this might be the best method
of locating that information. Among the most popular search engines are: Google http://www.google.com ,AlltheWeb http://www.alltheweb.com Yahoo http://www.yahoo.com, MSN Search http://search.msn.com Bai du Search www.baidu.com
Professional medical search engine
PubMed GoPubMed Pubget eTBLAST Cochrane Reviews,
The Cochrane Library Healia
Medical search engines
META-SEARCH TOOLS
Trip NLM Gateway Entrez, NLM's cross-database search SUMSearch
CONSUMER HEALTH SEARCH ENGINE
MedlinePlus by the U.S. NLM Healthfinder by the U.S. HHS Mednar Healthline Medstory
SOME PLACES TO SEARCH Bibliographic Databases Medicine
PubMed (or Ovid MEDLINE), EMBASE, Cochrane Library Multidisciplinary
Scopus Web of Science
Nursing and Allied Health CINAHL
Websites Associations, Organizations & Government
WHO, American Diabetes Association, Canadian Diabetes Association, Health Canada, Public Health Agency Canada etc...
Other “Grey Literature”
ProQuest Dissertations & Theses, conference proceedings (i.e., AMA), etc...
News and Alerting Services
Government Sources Press Releases, Fact Sheets,
Newsletters CDC "In the News" -
http://www.cdc.gov/od/oc/media/ NIH News and Events - http://www.nih.gov/news/ FDA New and Generic Drug Approval -
http://www.fda.gov/cder/approval/index.htm FDA Medical Products Reporting
- http://www.fda.gov/medwatch/index.html\
GENERAL HEALTH ALERTING SERVICES
•AMA News - http://www.ama-assn.org/public/journals/amnews/amnews.htm •Yahoo Health News - http://dailynews.yahoo.com/headlines/health/•Reuters Health http://www.reutershealth.com
3. CHOOSING SEARCH TERMS
BREAKING DOWN YOUR QUESTION
1. Select your database2. Break you question into concepts3. Identify subject headings for each
concept4. Identify keywords for each concept
Tips: Use a “target article” to help identify
search termsUse a concept map to keep track of
your terms
Database Password?High quality evidence only!
NHS Evidence www.evidence.nhs.uk(no password)
TRIP database www.tripdatabase.com(no password)
Cochrane Library www.thecochranelibrary.com(no password)
Great General Databases
PubMed (Medline)
www.pubmed.gov(no password)Use this version of PubMed to see reliable links to Cambridge journalsor Available via NHS ATHENS
Embase Available using RAVEN Login or Available using NHS ATHENS
1. Select your databaseDatabases for literature searching
WHY DO I HAVE TO SELECT A DATABASE FIRST? Your database will determine:
1. Your subject headings2. Your operators (i.e., truncation
symbols)
DIFFERENT DATABASES HAVE DIFFERENT SUBJECT HEADINGS
Database Subject Headings
Medline MeSH
EMBASE EMTREE
CINAHL CINAHL Headings
Cochrane Library MeSH
Web of Science N/A
Scopus N/A
3. IDENTIFYING CONCEPTS
Which concepts are contained in the question: Does ambulatory BP readings improve detection rates for hypertension in patients with type 1 diabetes mellitus?
1. Hypertension2. Diabetes Mellitus, Type 13. Ambulatory blood pressure readings
Concept #1
OVID MEDLINE SEARCH TERMS
Concept #2 Concept #3
Subject Headings
Keywords
AND AND AND
OR
Hypertension Diabetes Mellitus, Type 1 Blood Pressure Monitoring, Ambulatory
OR
OR
Hypertensi$.mp. (Diabetes mellitus adj5 (type 1 OR insulin?dependent OR juvenile?onset OR sudden?onset)).mp.
((blood pressure OR BP) adj2 (monitor$ OR test$) adj5 (home OR self OR ambulatory)).mp.
OR
((high OR elevated) adj2 (blood pressure OR BP)).mp.
Iddm.mp.
SOME KEY OPERATORS IN OVID
Operator Command$ Truncation (finds alternate endings)? Wildcard (finds alternate spellings).mp. Mapping Alias (tells Ovid to search for your term
in the Title, Abstract, Subject Headings, Table of Contents and Key Phrase Identifier fields) – useful for lit. reviews because it is broad
() Parentheses control the order of search operations
Adj Adjacency operator (can be followed by a number) tells Ovid terms must appear adjacent to one another
AND all terms must appear in resultsOR any terms will appear in results
Note: These are recommended operators for research lit reviews. There are many, many more operators... Use Ovid‘s Help menu to locate them.
4.RUNNING SEARCH Concept(titles , objectives) Searching using criterias and
parameters Screening Synthesizing the results
RUNNING YOUR SEARCH(ES) Start with your first concept
Search for the subject headings firstThen search keywordsCombine these synonymous searches with OR
using your search history
Repeat for your second, third, and subsequent concepts
Finally, combine large search results set with Boolean operator or others
Search #2 =
Search #3 =
Search #4 =
Search #5 = #1 OR #2 OR #3 OR #4
Search #1 =
Concept 1
Search #6 =
Search #7 =
Search #8 =
Search #9 =
Concept 2
Search #10 = #6 OR #7 OR #8 OR #9
Search #11 = #5 AND #10
Results
APPLYING PRACTICAL & METHODOLOGICAL
SCREENING CRITERIA
SCREENING Two kinds: practical and methodological
1. practical screening criteria Is to identify a broad range of potentially
useful studies
2. methodological screening Criteria
is to identify the best available studies
PRACTICAL SCREENING
1. Date of publication only studies conducted between 2005 and 2010
2. Participants of subjects only children 6 to 12 years of age
3. Publication language only materials written in English
4. Research design and methods The clinical trials, studies
METHODOLOGICAL SCREENING CRITERIAsome questions to ask
Is the study’s research design internally & externally valid?
Are the data sources used in the study reliable & valid? Are the analytical methods appropriate? (p value,
cooreation, regression, hypothesis etc) Are the results meaningful in practical & statistical
terms?*
*Fink, A. (2005). Conducting Research Literature Reviews. London: Sage.
APPLYING SCREENS (OR LIMITS) Apply practical
screens by using “limits” (may also be called “search options”) Eg. Advance option, by
date, by author ,time published etc
APPLY METHODOLOGICAL SCREENS BY READING THROUGH THE ARTICLES
MANUAL SEARCHING AND FINAL STEPS Locate the reference lists for selected
articles* Identify new articles that have cited
your articles* Identify key journals and “hand search”
their issues Test your search strategy by checking to
see if a few “target articles” appear in the results
* Use Web of Science or Scopus or else
WORKING WITH YOUR RESULTS Export search results from each
database or website into a citation manager (i.e., RefWorks)
Remove duplicates Remove inappropriate studies by
applying methodological screens
5. SYNTHESIZING THE RESULTS
LOOK FOR PATTERNS What conclusions did these studies reach? Which studies agreed/disagreed with the
consensus?
Consider using a synthesis matrix:www.ncsu.edu/tutorial_center/writespeak/download/Synthesis.pdf
USE YOUR RESULTS TO...1. Describe current knowledge about your
research topic2. Support the need for and significance of new
research3. Explain research findings4. Describe the quality of a body of research*
*Fink, A. (2005). Conducting Research Literature Reviews. London: Sage.
Thanks