Evidence-Based Medicine (EBM) - Issue 5 (Nov 2003)

Issue 5 November 2003

On this page

  1. General points
  2. What is EBM?
  3. Why is it important?
  4. How is it changing practice?
  5. Evaluating the evidence
  6. Tools and resources
  7. Acting on the evidence
  8. References

General points

  • The incorporation of evidence into practice may increase use of effective interventions and enable faster uptake of new, research-proven treatments
  • EBM does not replace clinical expertise; judgement and experience are needed to integrate evidence into day-to-day practice appropriately
  • Methodologies to help identify the best evidence have been developed to systematically summarise and evaluate the research literature
  • Good quality, ready–made summaries and evaluations are available from several sources

1

What is EBM?

EBM has been defined as “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients”.1 EBM is not about replacing clinical expertise with findings from the literature; clinical judgement and experience are necessary to know when and how to apply evidence to patient care. Effective use of EBM has four main stages:

  1. Formulating a clear clinical question
  2. Finding the evidence to answer the question
  3. Evaluating the evidence
  4. Integrating it into clinical practice

Why is it important?

Practitioners need a way to integrate evidence into their work, in order to optimise patient care and keep up with the latest research. It is not practical to read the ever-growing number of primary studies published in medical journals, and textbooks rapidly become out of date. EBM provides methodologies for systematically summarising and evaluating primary research, and offers access to existing high quality secondary research. Where gaps in the evidence exist, EBM can assist in exposing these, thus identifying priorities for the commissioning of new research.

How is it changing practice?

EBM has broad implications for clinical practice. By enabling identification of the most effective interventions, it allows practitioners to target limited resources more appropriately. Likewise, it may curtail the use of interventions which, although widely used, are not backed up by sound research. For example, the use of albumin in critically ill patients has declined appreciably since the publication of a Cochrane systematic review2 that concluded the practice may be harmful.3 EBM could also enable faster uptake of new interventions shown to be effective by research.

Evaluating the evidence

Critical appraisal of research literature lies at the heart of EBM. Studies are evaluated to determine their validity, reliability and relevance to the clinical question, and to detect any bias. In addition, evidence is often ranked according to the design of the research that yielded it, a concept sometimes referred to as the “level of evidence”. A variety of ranking systems exist;4,5,6 the general concept is outlined in Table1.7

Tools and resources

EBM is often seen as a time consuming activity that places additional demands on practitioners, requiring complex literature searches and detailed appraisals of studies. However, ready-made evaluations and quality secondary research are available from a number of sources (see Table2).8 These sources can assist practitioners in stages two and three of the EBM process.

Acting on the evidence

Having identified evidence that is valid and relevant, practitioners can integrate it directly into patient care or use it as a basis for team protocols or guidelines. At this stage it is important to consider how closely the study populations match those encountered in real life, and to determine how the harms and benefits reported in the research might impact upon individual patients. The relative costs of the treatments also need to be taken into account.

References

  1. Sackett DL et al. Evidence-based medicine: what it is and what it isn’t. British Medical Journal, 1996;312:71-72.
  2. Alderson P et al. Human albumin solution for resuscitation and volume expansion in critically ill patients (Cochrane review). In: The Cochrane Library, 3, 2003. Oxford: Update Software.
  3. Webster NR. Evidence based practice in intensive care: light on the horizon? British Journal of Anaesthesia, 2001;87(3):377-379.
  4. New Zealand Guidelines Group. Evaluating the medical literature: evidence grading.
  5. Scottish Intercollegiate Guidelines Network (SIGN). Section 6. Forming guideline recommendations. Figure 6.2 Revised SIGN grading system. See www.sign.ac.uk/guidelines/fulltext/50/section6.html
  6. Centre for Evidence-Based Medicine. Oxford Centre for Evidence- Based Medicine levels of evidence (May 2001). See http://www.cebm.net/index.aspx?o=1025
  7. Adapted from: School of Health and Related Research (ScHARR). Systematic reviews: what are they and why are they useful? Section 3.2 Hierarchy of evidence. See www.shef.ac.uk/~scharr/ir/units/systrev/hierarchy.htm
  8. Adapted from: Craig JC, Irwig LM & Stockler MR. Evidence-based medicine: useful tools for decision making. Medical Journal of Australia, 2001;174:248-253
© ACC2003 • Printed November 2003