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Evidence based practice

Evidence based practice

What is evidence based medicine?

This guide aims to collect all the best tips, advice and resources to help to locate evidence to support the practice of Evidence Based Medicine (EBM).

Evidence Based Medicine is an approach to forming medical knowledge, based on systematic and unbiased methods of appraising scientific evidence (Source: BestBETs).

Evidence-based medicine (EBM) is the integration of best research evidence with clinical expertise and patient values (Source: Ebling Library, University of Wisconsin).

The Key Steps in Evidence Based Practice (EBP) (continues in What is EBM?)

Evidence-based practice (EBP) is the inclusive term which the principles of EBM are founded; primarily EBP is based on five well defined steps.

  • Step One: Asking Focused Questions: translation of uncertainty to an answerable question
  • Step Two: Finding the Evidence: systematic retrieval of best evidence available
  • Step Three: Critical Appraisal: testing evidence for validity, clinical relevance, and applicability
  • Step Four: Applying the Evidence: application of results in practice
  • Step Five: Evaluating Performance: auditing evidence-based decisions


What is PICO

The PICO framework is an effective tool for constructing a well built clinical question.

PICO stands for:

Patient or Problem
Comparison intervention (if appropriate)

A well built clinical question:

  • gives you a head start in finding information that is relevant (applicable to the patient) and valid (accurately measures what the authors state they intend to measure.)
  • provides you with a checklist for the main concepts to be included in your search strategy.
  • allows you to find information quickly. If tracking down the evidence takes too long, you will probably avoid it in your clinical practice.

From 'Formulate a Clinical Question', The University of Western Australia 

Formulating an answerable question using PICO

P - Patient, Population, or Problem How would you describe a group of patients similar to yours? What are the most important characteristics of the patient? This may include the primary problem, disease, or co-existing conditions. Sometimes the sex, age, or ethnicity of a patient might be relevant to the diagnosis or treatment of a disease.

I - Intervention, Prognostic Factor, or Exposure Which main intervention, prognostic factor, or exposure are you considering? What do you want to do for the patient? Prescribe a drug? Order a test? Order surgery? What factors may influence the prognosis of the patient? Age? Co-existing problems? What was the patient exposed to? Asbestos? Cigarette Smoke?

C - Comparison of Intervention (if appropriate) What is the main alternative to compare with the intervention? Are you trying to decide between two drugs, a drug and no medication or placebo, or two diagnostic tests? Tour clinical question may not always have a specific comparison.

O - Outcome you would like to measure or achieve What can you hope to accomplish, measure, improve or affect? What are you trying to do for the patient? Relieve or eliminate the symptoms? Reduce the number of adverse events? Improve functions or test scores? (Source: Ebling Library, University of Wisconsin-Madison)

Example of a PICO question

Patient or Problem




Child with frequent, recurrent acute tonsillitis



Tonsillectomy is warranted in children with frequent, recurrent acute tonsillitis

Type of  evidence

TRIP database – evidence based guidelines

Cochrane database of systematic reviews (synthesis of randomised controlled trials)

EBM resources

Something not working - report a problem with access.

Evidence based medicine guides

EBM Guides

Formulating your question

Types of studies

Critical appraisal

Levels of evidence

EBP glossaries

EBP calculators

Finding the best evidence

The strongest evidence is in the secondary or pre-appraised research.

The 6S model evidence pyramid

The pyramid is divided into levels with the strongest evidence at the top. Systems is not widely used. Begin with Summaries. If you cannot find the information in Summaries continue down the pyramid remembering that the strength of the evidence decreases as you go further down the pyramid.

DiCenso A, Bayley L, Haynes B. Accessing preappraised evidence: fine-tuning the 5S model into a 6S modelACP J Club. 2009; Vol 151 Issue 3: p1


Synopses of Syntheses

  • ACP Journal Club (Evidence-Based Medicine Reviews (EBMR, Ovid menu)
  • Database of Abstracts of Reviews of Effectiveness (DARE) (EBMR, Ovid menu)

Syntheses (Systematic Reviews)

  • Cochrane Database of Systematic Reviews (EBMR, Ovid menu)

Synopses of Single Studies

  • ACP Journal Club (EBMR, Ovid menu)

Appraisal, decision making and evaluation

Appraising the evidence

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)

Making a decision

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?

Evaluating your performance

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?

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)

Tools and references


Covidence,  Covidence is a core component of Cochrane’s review production toolkit. (requires separate subscription but can get a free trial)

EBM resources, Centre for Evidence-Based Medicine (UK)

Introduction to Evidence-Based Practice Tutorial from Duke University Medical Centre Library and Health Science Library

Evidence-Based Medicine Toolbox

Users' guides to the medical literature

Answering clinical questions (Univ of WA) 


DiCenso, A, Bayley, L, Haynes, B 2009, Accessing preappraised evidence: fine-turning the 5S model into a 6S model [editorial], ACP J Club, vol. 151, issue 3, pp 1-2.

Greenhalgh, T 2014, How to read a paper: the basics of evidence-based medicine, 5th edn, Chichester, West Sussex, John Wiley & Sons.

Heneghan, C, Badenoch, D 2006, Evidence-based medicine toolkit, 2nd edn, Malden, Massachusetts, BMJ Books/Blackwell Publishing.

Sackett, DL, Rosenberg WMC, Gray, JAM, Haynes, RB, Richardson, WS 1996, Evidence-based medicine: what it is and what it isn’t, BMJ, vol. 312, pp. 71-72.

How to read a paper bmj

Cochrane handbook