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Evidence Based Literature Searching

Thinking about the type of study will help you build a good clinical question.

Looking the image of the pyramid the quality of the references goes up  but the amount of references you might find goes down.

This list goes from the bottom of the pyramid to the top.

  • Background/Expert Opinion
    Evidence in these resources may vary from expert opinion to high levels of evidence
  • Case Series/ Case Reports
    Consist of collections of reports on the treatment of individual patients or a report on a single patient. Because they are reports of cases and use no control groups with which to compare outcomes, they have little statistical validity.
  • Case Controlled Studies
    A case control study starts with patients who already have the outcome and looks backwards to possible exposures.
  • Cohort Studies
    A cohort study starts with the exposure and follows patients forward to an outcome.
  • Randomized Controlled Trials (RCTs)
    Randomly assigns the exposures and then follows patients forward to an outcome.
  • Critically Appraised Individual Articles [Article Synopsis]
    Authors of critically-appraised individual articles evaluate and synopsize individual research studies.
  • Critically Appraised Topics [Evidence Synthesis]
    Authors of critically-appraised topics evaluate and synthesize multiple research studies.
  • Systematic Reviews
    Authors of a systematic review ask a specific clinical question, perform a comprehensive literature search, eliminate the poorly done studies and attempt to make practice recommendations based on the well-done studies.

Based on the EBM Pyramid. Copyright © 2006–2011. Trustees of Dartmouth College and Yale University. All Rights Reserved. Produced by Jan Glover, David Izzo, Karen Odato and Lei Wang.

CCHMC Evidence Collaboration: James M. Anderson Center for Health Systems Excellence | Center for Professional Excellence
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