Notes
Slide Show
Outline
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Step 2:
  • Locating the Evidence
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Table of Contents
  • Evidence Pyramid
    • Filtered Information
      • Systematic Reviews/Meta-Analyses
      • Critically-Appraised Topics (Synthesis)
      • Critically-Appraised Articles (Synopsis)
    • Unfiltered Information
      • Randomized Controlled Trials
      • Cohort Studies
      • Case-Controlled Studies/ Case Series and Reports
      • Background Info/ Expert Opinion
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Evidence Pyramid
  • The best evidence is located at the top of the pyramid.


  • Click on one of the sources of evidence to learn more.
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Filtered Information
  • Appraise and/or synthesize information from previous studies
  • Organize it into a single coherent analysis
  • Provide recommendations for future practice.
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Systematic Reviews/ Meta-Analyses
  • Systematic reviews
    • Comprehensively synthesize and critically appraise information from various articles that meet specific selection criteria
    • Provide recommendations based on the best evidence available
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Systematic Reviews/ Meta-Analyses
  • Meta-analyses
    • Are systematic reviews using statistical methods to quantitatively combine and summarize several studies’ results
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Critically-Appraised Topics (Synthesis)
  • Briefly evaluate and synthesize results from several studies on a particular topic that provide the best available evidence relevant to answering a specific clinical question
  • Less rigorous than systematic reviews/meta-analyses
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Critically-Appraised Articles (Synopsis)
  • Provide a brief synopsis and appraisal of a single study that provides evidence relevant to answering a specific clinical question
  • Less rigorous than systematic reviews/meta-analyses
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Unfiltered Information
  • The evidence sources from which the above ones acquire their information (i.e. the primary sources)
  • Useful when filtered information is not available
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Randomized Controlled Trials
  • Randomly assigns subjects into a treatment group or a control group in order to compare the efficacy of a particular treatment, diagnosis, etc. against the current standard, a placebo, or no intervention at all.
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Cohort Studies
  • Compare two groups of subjects over time, one having a particular condition or receiving a particular treatment, the other not
  • Often used when a randomized controlled trial would be unreasonable or unethical.
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Case-Controlled Studies/ Case Series and Reports
  • Retrospective observational studies of a particular diagnosis or exposure
  •  Determine commonalities in medical history or other associations amongst the affected
  • Can establish correlations, but cannot prove causation
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Background Info/ Expert Opinion
  • Based on clinical experience and case studies
  • Varies in level of scientific rigor and usefulness.
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Try it Yourself:
  • Search Basics & Using PubMed
  • More Advanced Searches & Using the Cochrane Library
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Additional Resources for
Systematic Reviews\ Meta-Analyses
  • Online Resources:
  • PubMed
  • Cochrane Library
  • Selected Readings:
  • Systematic Reviews: Synthesis of Best Evidence for Clinical Decisions by Cook, D. J., et al.
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Links to Other Websites
and Hands-On Activities
  • From Duke University Medical Center Library and Health Sciences Library, UNC-Chapel Hill
    • Types of Studies
  • From Yale University School of Medicine
    • Evidence Pyramid from a Slightly Different Perspective


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Congratulations!
You have successfully completed Step 2 –
Evidence Pyramid.
The End