Searching the medical literature aug 2010Presentation Transcript
Searching the Medical Literature Robin Featherstone Clinical Medicine Librarian UWO [email_address] http://www.slideshare.net/featherr Selinda Berg Clinical Medicine Librarian Windsor [email_address]
List four categories of information resources
Apply selection criteria to identify appropriate information resource
List five databases to find primary studies
Strategize and execute a systematic, explicit and reproducible search of the biomedical literature
Level of Evidence Pyramid Qualitative Studies
Systems, Synopses & Summaries Systems Synopses Summaries Few exist Number in the thousands Fewer than 50,000 Textbook-like; integrate clinical evidence with other types of info; directed at clinical practice decisions Summaries of studies and systematic reviews; includes guides or advice from expert clinicians Systematic reviews of articles and guidelines; you assess and make decisions Very easy to use Easy to use May require searching
Criteria for Selecting a Resource
Soundness of evidence-based approach
Comprehensiveness and specificity
Ease of use
Questions to Ask
Bias? Conflict of interest?
Evidence grading or ranking applied?
Consistent and quick to search?
Available in my location?
Number in the millions
No processing of evidence – must individually assess
Require searching large databases
Available from Western Libraries (or for free) Find at: www.lib.uwo.ca/programs/undergraduatemedicaleducation/ Systems Synopses Syntheses Studies
ACP Journal Club
InfoPOEMS ( Essential Evidence Plus)
DARE (Database of Reviews of Effects)
Centre for Reviews and Dissemination
Cochrane Database of Systematic Reviews
US National Guidelines Clearinghouse
Cochrane Controlled Trials Registry (CCTR)
Web of Science
HOW TO SEARCH STUDIES
A Comprehensive Search is...
7 tasks in a comprehensive search
Develop a search statement or question
Select a source
Choose search terms
Run the search
Apply practical screens (limits)
Apply methodological screens
Synthesize the results
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
Sample Search Statements
I am looking for articles about osteoarthritis of the knee.
13,886 articles in PubMed
I am looking for RCTs on arthroscopic surgery for osteoarthritis of the knee that include placebo surgery as a control.
9 articles in PubMed
I am looking for RCTs on arthroscopic surgery conducted in latino females with type 1 diabetes mellitus.
0 articles in PubMed
Turn your statement into a strategy
Break you question into concepts
Identify subject headings for each concept
Identify keywords for each concept
Use a “target article” to help identify search terms
Use a strategy worksheet to keep track of your terms:
Does hand washing prevent MRSA? in the ICU? Hand washing MRSA ICU Prevention Handwashing [MeSH] Methicillin-Resistant Staphylococcus aureus [MeSH] Intensive care units [MeSH] + Handwash$.mp. Methicillin resistant staphylococcus aureus.mp. Intensive care unit$.mp. Prevent$.mp. Hand wash$.mp. MRSA.mp. ICU.mp. Hand disinfect$.mp. Critical care unit$.mp. Surgical scrub$.mp. Hand clean$.mp.
Different databases have different subject headings
Complete a concept map for each database that you search
Select subject headings that are the closest match for your concept (remember: systematic, explicit and reproducible)
Pay attention to “explode” commands – some databases will search related headings by default, others will not
Database Subject Headings Medline MeSH EMBASE EMTREE CINAHL CINAHL Headings Cochrane Library MeSH Web of Science N/A Scopus N/A
Some key operators in Ovid Note: These are recommended operators for research lit reviews. There are many, many more operators... Use Ovid‘s Help menu to locate them. Or see: http://content.library.utoronto.ca/gerstein/subjectguides/ovidmedline_shortcuts.pdf 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 results OR any terms will appear in results
How does patient adherence to medication regimens influence outcomes following surgery for myocardial infarction? Source: Practical Screens:
Running your search
Running your search(es)
Start with your first concept
Search for the subject headings first
Then search keywords
Combine these synonymous searches with OR using your search history
Repeat for your second, third, and subsequent concepts
Finally, combine large search results set with AND
Running your search(es) 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