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Evidence-Based Practice

Learn how to define and search for the common types of high level evidence used in clinical research

What is Evidence-Based Practice (EBP)?

The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research (Sackett et al. 1996)

  • EBP is the best evidence available to inform clinical practice.  Usually the types of evidence are represented as hierarchical levels, often portrayed in a pyramid. It is also sometimes called evidence-informed practice.
  • Note that the quality of evidence available will vary according to the type of clinical question.  For example, you may be able to find a systematic review that matches your topic, or there may only be single studies available.
  • When searching for best evidence in clinical evidence databases, ‘less is more’ is a useful rule to follow.  Find out the correct clinical term(s) for your topic and use this as your main search term (for example, use the term ‘pressure ulcer’ rather than ‘bedsores’).  Add a second search term if the first search results are too many to scan through.

 

Sackett, DL, Rosenberg, WM, Muir Gray, JA, Haynes, RB, Richardson, WS 1996, 'Evidence Based Medicine: What It Is And What It Isn't:', BMJ: British Medical Journal, vol. 312, no. 7023, pp. 71-72, 
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2349778/pdf/bmj00524-0009.pdf>.

The 6S Pyramid

There are a number of different pyramid models showing levels of evidence for EBP. 

The different levels and different names given to types of evidence in these pyramids can be confusing. Some put systems at the top, others start with systematic reviews, or clinical guidelines.  Don’t worry too much about these variations.  If you are lucky enough to find a clinical guideline and a systematic review on your topic – rejoice, because you have found two very high level sources!

The example shown here is the ‘6S’ model (DiCenso, Bayley, & Haines 2009).  It has five ‘filtered’, or ‘pre-appraised’ levels, and one ‘unfiltered’ level. ‘Filtered’ means that the original studies have been critically evaluated to some degree by experts, and therefore the evidence is considered more reliable than the single studies.

The 6S hierarchy of pre-appraised evidence

DiCenso, A, Bayley, L, Haynes, RB 2009, 'Accessing pre-appraised evidence: fine-tuning the 5S model into a 6S model', Evidence-Based Nursing, vol. 12, pp. 99-101,
<https://ebn-bmj-com.ezproxy.utas.edu.au/content/ebnurs/12/4/99.2.full.pdf>.

 

Pyramid levels explained

To find the highest level evidence on your topic, start at the top of the pyramid and work down, using the suggested databases for each level.