Searching for medical information biostats
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Transcript of Searching for medical information biostats
Searching the LiteratureBiostats
Susan Fowler, MLIS
Medical Librarian
314‐362‐8092
pg: 314‐360‐1069
Outline• Search Strategy• Pulling Keywords from Your PICO Question• Boolean, Truncation, and Wild Cards• Hierarchy of Evidence and Study Design• Google Scholar• Cochrane Database of Systematic Reviews• PubMed (MEDLINE)• EMBASE
Choosing Appropriate EvidenceHigher Quality
Percentage of the Literature Meta‐
analysesSystematic reviews
Randomized controlled trialsProspective blind comparisons
Cohort studies
Case‐control studies
Case series and case reports
Animal and laboratory research
Will Olmstadt, MS, MPH
PICO
• Patient or problem ‐ How would I describe a group of patients similar to mine?
• Intervention ‐Which main intervention, prognostic factor, or exposure am I considering?
• Comparison ‐What is the main alternative to compare with the intervention?
• Outcome ‐What can I hope to accomplish, measure, improve or affect?
Will Olmstadt, MS, MPH
The Search Strategy
• Develop PICO question
• Identify keywords and terms from PICO
• Identify standardized subject headings
• Combine subject headings and keywords to narrow or broaden your search
• Evaluate your search results
• Revise the search in light of your results
Pulling Keywords from Your PICO Question
• What are the main topics of your PICO?
• Brainstorm – what other words could you use to describe your topic?
• What are some synonyms for the words you’ve come up with?
Evaluate the Search Results
Don’t be afraid if you have zero (0) or thousands of results, play around with search strategies – you wont break anything!
– Read the titles and abstracts of “hits” in your search to get a feel for their relevance
– Identify relevant MeSH and Keywords used to index particularly relevant “hits”
– If your search yields too many or too few hits, modify it and try again
Revise the Search in Light of your Results
• Narrow the search by combining search terms and applying limits
• Broaden the search if the results are too limited by removing keywords and limits
Boolean
• AND
• OR
• NOT
Boolean
strawberry AND AND chocolate
Strickland, Jennifer and Henderson, John R. (October 10, 2005). Boolean Logic. Retrieved September 22, 2007, from http://www.ithaca.edu/library/course/expert.html.
Booleanstrawberry OR OR chocolate
Strickland, Jennifer and Henderson, John R. (October 10, 2005). Boolean Logic. Retrieved September 22, 2007, from http://www.ithaca.edu/library/course/expert.html.
Boolean and Nesting(strawberry OR NOT chocolate
Strickland, Jennifer and Henderson, John R. (October 10, 2005). Boolean Logic. Retrieved September 22, 2007, from http://www.ithaca.edu/library/course/expert.html.
Truncation and Wild Cards• Truncation is a searchable shortened form of a word.
– adolescen* will include• adolescence• adolescent• adolescents, etc…
• Wild card characters are useful because of alternate spellings and other quirks in the English language. – behavio?r, will include
• behaviour • behavior
– Wom*n, will include• women • woman
Quotation Marks
Using quotation marks for a phrase forces the database to return results where those words appear together.
Without Quotations = 57,360 results With Quotations = 13,180 results
Google Scholar
• http://scholar.google.com/• Freely accessible database of a vast array of materials
and media archived in the web• Customizable to point to your full text available through
your library• Customizable to send citations to your citation manager• Set up auto search alerts to track materials that match a
specific search query
Go to“Advanced
Scholar Search”
Advanced Scholar SearchUse truncation
Search exact phrases
Use limits to narrow results by specific author, publication, and
date range.
Narrow by subject area
Set Up AlertClick the envelope
to access the alert service.
Set Up Alert, cont…
Alerts will automatically be sent to your email.
Scholar Preferences
Scholar Preferences, cont…
Cochrane Database of Systematic Reviews
• http://www.cochrane.org/
• “Gold Standard” for systematic reviews
• Free database, but requires paid subscription to access most content
Cochrane
Cochrane Search Example
Question: Does the use of Echinacea really prevent the common cold?
You are only interested in
Cochrane Reviews
Cochrane Search Example cont…You are only interested in
Cochrane Reviews
Click “Record” to view details of review and access full text if
available.
Cochrane Systematic Reviews
Pros– Compiled through rigorous standards
– Review process has already been done so you don’t have to
Cons– Limited content
– Limited search capabilities
– Access to most full‐text content requires paid subscription
PubMed (MEDLINE)
• www.pubmed.gov
• Created and maintained by the National Institute of Health (NIH) and the National Library of Medicine (NLM)
• 17 million citations back to 1950s
• Free database of citations with some content available for free
MeSH = Medical Subject Headings
Choose MeSH from Pull Down Menu
MeSH in PubMed
Enter your search terms one at a time…
PubMed - MeSH cont…
Choose the most applicable MeSH terms
PubMed - MeSH cont…
Send to Search Box
PubMed ‐MeSH cont…
Click “Search PubMed”
PubMed – Advanced Search
PubMed – Advanced Search
Enter search numbers and combine using Boolean operators.
PubMed - Limits
PubMed - Limits cont…For the most clinically applicable articles, limit to “Humans,” “English,” and “Type of Article”
PubMed – Limit to Type of Article
Tier 1• Meta‐Analysis
• Practice Guideline
• Randomized Controlled Trial
• Review
• Guideline
• Multicenter Study
Tier 2• Clinical Trial
• Clinical Trial, Phase I
• Clinical Trial, Phase II
• Clinical Trial, Phase III
• Clinical Trial, Phase IV
• Comparative Study
• Controlled Clinical Trial
• Research Support, N.I.H., Extramural
• Research Support, N.I.H., Intramural
• Research Support, Non‐U.S. Gov't
• Research Support, U.S. Gov't, Non‐P.H.S.
• Research Support, U.S. Gov't, P.H.S.
Accessing Full‐Text Articles
Avoid clicking on publisher icons unless they explicitly state that they are free or unless you are willing to pay $ 35.00 ‐65.00 dollars per article.
Accessing Full‐Text Articles cont…
It is likely that your institution’s library has facilitated link‐out in PubMed to link you directly to articles from journals to which they subscribe to.
It is also likely that your institution’s library has an Inter‐Library Loan service that will “borrow” the article you want from another library for you for a small charge (certainly less then $35.00!) or for free.
Contact your librarian and find out what services are available and how to use them.
PubMed - Send To
You can email your results to yourself and your colleagues.
From “Send to” drop down menu, choose
“E‐mail”
PubMed - Search History
Don’t forget to save your search history!
PubMed (MEDLINE)
PubMed advantages– Free to search
– No username/password
– Searches same content as Ovid MEDLINE
– Links to free full‐text sometimes available
PubMed disadvantages– Still have to appraise articles
once located
EMBASE• Over 56,000 preferred terms (of which more than 27,000
are drugs and chemicals) – more than twice as large as MeSH
• More than 230,000 synonyms (with over 144,000 drugs and chemical synonyms)
• Requires a paid subscription to access
• over 20 million indexed records from more than 7,000 active, peer‐reviewed journals
• over 2,000 biomedical titles not offered by Medline
• Index conference abstracts
EMBASE - Emtree
Click Emtree to access database of standardized terms
EMBASE – Emtree, cont…
EMBASE – Emtree, cont…
EMBASE – Advanced Search
Good Database Searching Rules
Following these rules will improve your results…
1. Think out your query, pull out individual concepts2. Search individual concepts alone and combine them later from search
history3. Apply Limits to narrow your search and make it more specific to your needs4. Keep a copy of your search history. 5. If it takes you longer then 20 minutes – ask your librarian for help.
Library Locations
• 660 S. Euclid314‐362‐7085
Susan Fowler, 314‐362‐8092
Pg: 314‐360‐1069
• BJ North, Rothschild Medical LibraryReka Kozak, 314‐454‐7208
• St. Louis Children’s HospitalLauren Yaeger, 314‐454‐2768