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Evidence-Based Medicine: Finding the Evidence

A guide to evidence-based medicine resources in UVic Libraries.

The Hierarchy of EBM Resources

The hierarchy of pre-appraised evidence is a helpful model for guiding clinical decision making. The model proposes layers of evidence sources and the search for EBM resources should begin at the highest possible layer, Systems. To find the best evidence on low carb diets, for example, since we don’t have access to a Systems resource, such as a computerized decision support system linked to individual patients’ medical records, we begin by looking for a Summary resource such as FirstConsult or EBM Clinical Practice Guidelines on our topic. If we can’t find the information we need from a Summary resource, we next search a Synopses of Syntheses resource[s] on the  topic such as a meta-analysis or a systematic review on the topic. Then, if necessary, we proceed to find evidence on our topic by searching resources on the next lowest level on the hierarchy pyramid, Synthesis, and so on, down the pyramid.  

Levels of Evidence Pyramid

This pyramid depicts one viewpoint of information resources providing various levels of evidence. The strongest evidence is that found near the top of the pyramid. As one progresses down the pyramid, the strength of evidence in the content generally decreases.

The 6S Model of Evidence

Adapted by L. Tjosvold from: DiCenso, A,Bayley, L, Haynes, RB. Accessing pre-appraised evidence: fine-tuning the 5S model into a 6S model. Evid Based Nurs 2009;12:99-101. http://ebn.bmj.com/content/12/4/99.2.extract