The purpose of critical appraisal is to determine the relevance of the material collected in relation to the clinical question raised. In other words, does the evidence provide the answer to the question raised and how confidently can the evidence be applied to practice? (Source: Cleary- Holdforth J, Leufer T, 2008 ‘Essential elements in developing evidence-based practice' Nursing Standard. 23, 2, 42-46)

• Appraising the Evidence – From the book, Evidence-Based Practice for Information Professionals: A Handbook Edited by Andrew Booth and Anne Brice
• Critical Appraisal - useful tools and downloads for the critical appraisal of medical evidence from the Centre for Evidence Based Medicine
• Critical Appraisal Skills Program (CASP, UK)

Once the evidence has been appraised, and the best available evidence selected, it must be applied to your local situation. How it is applied will depend on its relevance to local conditions. (Source: The University of Newcastle Australia, viewed online 18 February 2011)

Below is a list of questions you may ask to help determine how evidence applies:

• Is the test affordable, accurate and available in my hospital?
• Can I estimate the pre-test probability of the disease in question?
• Will the post-test probability affect my management?
• Is my patient so different from those in the study group that the results can not be applied?
• According to the study results, how much would my patient benefit from the treatment?
• Can the study results be applied to my patient?
• What is my patient's risk for adverse affects?
• Are there alternative therapies?
• Is my patient similar to the patients in the study group?
• How will the evidence influence my choice of treatment?

To complete the cycle of practising evidence based medicine clinicians should evaluate their own performance, and this fifth step of self evaluation allows clinicians to focus on earlier steps that may need improvement in the future. Clinicians can evaluate their progress at each stage by asking some or all of the following questions:

• Was the question answerable?
• Was the diagnosis and treatment successful?
• How quickly was good evidence located?
• Is there new information/data in the literature?
• How can I improve/update my clinical decision?
• How effectively appraised was the evidence?
• Was the application of the new information or procedure effective?
• Should this new information and/or clinical practice procedure continue to be included in day to day applications?
• How could any of the 5 steps improve the next time a question is asked?

Sources:
Straus, E and Sackett D L 1998, ‘Getting research findings into practice Using research findings in clinical practice' BMJ Vol.317 p.339-342)
Johnson, C 2008, ‘Evidence-based practice in 5 simple steps' Journal of Manipulative and Physiological Therapeutics Vol. 31 p.169-170
Evidence-Based Practice, University of Minnesota Libraries, viewed online 18 February 2011
Evaluating evidence-based practice performance – (Article) By Michael L Green (Source: Evidence Based Medicine 2006; Vol. 11; pages. 99-101)