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How to practice EBM

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How to practice EBM

• Ask an answerable clinical question • Search for evidence• Appraise the evidence• Translate into actions • Evaluate the performance

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Ask an answerable clinical question

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Elements of questions for therapeutics

• participants

• interventions

• comparison

• outcomes

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Search for evidence

• All evidence are not equal• Where and what to search• How to search

6Expert opinion, physiology, bench research

5[D]Case series4[C]Case-control study3b

Systemic review of case-control studies

3a‘Outcomes’ research2cCohort study or poor RCT2b

Systemic review of cohort studies

2a[B]‘All-or-none’1cSingle RCT1bSystemic review of RCTs1a[A]

TherapyLevel of Evidence

Grade of Recommendation

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Where and what to searchElectronic resources• PubMed• Textbooks• Journals• Official websites of academic organizations

or government agencies• Specialized databases for evidence-based

medicine• Filtered databases for evidence-based

medicine

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Example Specialized databases• Drug databases

– Micromedex• Travel advise

– CDC travel: http://wwwn.cdc.gov/travel/• Clinical guidelines

– National Guideline Clearinghouse™ (NGC) http://www.guideline.gov/

• Electronic textbooks– UpToDate

http://www.uptodate.com/home/index.html

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EBM ResourcesSystematic Literature Searches

• Cochrane Library (OVID)• Database of abstract of review of

effectiveness (DARE)

• Clinical Evidence

Systematic Literature Surveillance• ACP Journal Club (OVID)• National Guidelines Clearinghouse (AHRQ)• ClinicalTrials.gov

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The Cochrane library

• Cochrane Database of Systematic Reviews

• Database of Abstracts of Reviews of Effectiveness

• Cochrane Controlled Trials Register

• Cochrane Review Methodology Database

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ACP Journal Club• About 100 journals systematically

surveyed• Clinically relevant, highest-validity

articles abstracted• Structured abstracts to guide

critical appraisal• Clinical commentary

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ACP Journal Club• Limitations

– individual article summaries not systematic reviews

– cost ?

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Guidelines• Clinical Practice Guidelines may

be– Explicit evidence-based– Evidence-based– Opinion-based– “expert consensus”– National Guideline Clearinghouse™ (NGC)

http://www.guideline.gov/

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ClinicalTrials.gov• NIH, NLM, FDA sponsored• Database of clinical trials in progress• February 2000• Clinical trials need to be registered in

a public database order to get published in major journals

• US and CA – 80 countries

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PubMed• Freely available online since 1997at http://www.pubmed.gov

• Including MEDLINE and out of scope papers from MEDLINE journals

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Medline

• Acronym for Medical Literature Analysis and Retrieval System On-Line

• Computerized database of medical, dental, nursing and basic life science journals.

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Organization and Features of PubMed

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Organization of PubMed Record

• Field tags– PMID– Title– Authors– Source– Abstract– Medical subject headings– Publication date– Language– Publication type

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Field Tags

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PubMed Services

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Features of PubMed Services• Search box

– Limits– Preview/Index– History– clipboard– Details

• Display format and options– Summary– Abstract plus– Medline

• Related articles• Links• Clinical queries• My NCBI

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Search Box Features

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Features of PubMed Services• Search box

• Boolean operations of search terms ---capitalized words

– AND, OR, NOT– Works from left to right unless parentheses are used

– Limits– Preview/Index– History– clipboard– Details

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Features of PubMed Services• Display format and options

– Summary– Abstract plus– Medline

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Features of PubMed Services

• Related articles• Links• Clinical queries

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How MEDLINE Search works• Automatic term mapping

1. MeSH translation table2. Journal translation table3. Phrase list4. Author Index

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Medline Searching Strategies1. Free text and automatic term

mapping2. Title search3. Clinical queries4. Related articles5. Medical subject headings

• No strategy is perfect

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Search Strategy 1• To limit your search to useful evidence

first

• Add AND (“Cochrane Database SystRev”[journal] OR “ACP J Club” ”[journal])to the end of your search

• Boolean operations work from left to right unless parentheses are added

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Search Strategy 2• One very efficient searching

strategy is to use title search or clinical queries to quickly find one relevant article

• Use the Related articles and MeSHmethods for more exhaustive search

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My NCBI and Search Strategies

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