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  • Define evidence-based medicine

  • Identify the steps involved in evidence-based medicine

  • Illustrate the purpose of evidence-based medicine

  • Identify the hierarchy of evidence

  • Discuss strengths and limitations of evidence-based medicine


  • Clinical expertise

  • Clinical significance

  • Evidence

  • Evidence-based medicine (EBM)

  • External validity

  • Hierarchy of evidence

  • Internal validity

  • Patient values and preferences

  • PICO


With increasing disease complexities and treatment options, there is a need to incorporate emerging clinical evidence into decision-making to provide safe, high quality, and cost-effective patient care. The best approach to dealing with a clinical situation is not always apparent, and it is impossible to know the right thing to do in all situations. Evidence-based medicine (EBM) provides a scientific framework for asking and answering clinical questions to meet the needs of patients in a variety of settings. Evidence-based medicine (EBM) was initially defined as “a systemic approach to analyze published research as the basis of clinical decision-making.”1 This definition emphasized the use of research evidence to patient care. This is a paradigm shift in patient care from experience and expertise emphasis to incorporation of evidence in patient care.

The most recent and widely accepted definition of EBM incorporates evidence along with clinical experience and patient preferences into the decision-making process to increase the likelihood that the patient will receive helpful interventions and decrease the possibility of them receiving interventions that are likely to be harmful or ineffective. EBM is now defined as “the integration of best research evidence with clinical expertise and patient values.”2 While the specific area of practice or discipline is sometimes used in the description such as evidence-based pharmacy or evidence-based nursing, this chapter will use the broad definition of “medicine” to reflect the delivery of healthcare in general. This chapter will cover the history of EBM and its purpose. The steps involved in EBM are presented along with the various types of evidence that may be incorporated. Finally, the advantages and disadvantages of EBM are discussed.


Since antiquity, knowledge and skills regarding the delivery of healthcare have generally been passed from one generation of practitioners to the next. This clinical experience approach to patient care, which often includes incorporating background information about anatomy, physiology, and pharmacology along with the clinical experience gained from previous patient encounters, is fraught with peril due to its nonsystematic, potentially biased nature. A second approach dating to around the turn of the 19th century was to base patient care on experimental physiology.3 Using animal models, the presumed cause of diseases was elucidated and a treatment that was thought to address that particular cause was delivered (Figure 15-1). The main problem with using this approach in isolation is that it put too much emphasis on the question “why should this treatment work” ...

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