Introduction to evidence-based medicine (Proceedings)


Introduction to evidence-based medicine (Proceedings)

Nov 01, 2010

The principles of evidence-based medicine (EBM) were first developed by clinical epidemiologists during the late 1980's.1 EBM has been described as "the integration of the best research evidence with our clinical expertise and our patient's unique values and circumstances".2 The intent of EBM is to improve clinical decision making by acquiring, assessing, and utilizing evidence that is most clinically relevant: whenever possible, the evidence on which our clinical activities are based should be derived from well designed studies of patients (i.e., those with naturally occurring disease). In its current form, EBM refers not only to this laudable intention but also to a methodology by which this intention is realized. The methodology of EBM consists of the following 5 steps: 1) asking a clinically important question; 2) searching for evidence to answer the clinical question; 3) critically appraising the evidence gathered; 4) applying the results of the first 3 steps to one's patient(s); and, 5) assessing the outcome of applying the results (i.e., how well did the EBM-derived answer work?).3


The first step in EBM is stating the question(s) of interest about the patient. This is not always as simple as it might seem. Performing a search for too broad a question may yield numerous irrelevant citations, whereas a question that is too focused may yield no results. Any clinical encounter will generate a number of questions related to signalment and history, clinical examination findings, etiology and differential diagnosis, diagnosis, treatment, prognosis, prevention, and client experiences. Attempting to answer all the relevant questions simultaneously, however, will be unrewarding for the clinician, client, and patient. Thus, it is important to prioritize one's efforts. The PICO system for stating questions is recommended by many EBM adherents. PICO is an acronym in which P represents the patient or patient circumstances, I represents the intervention of interest, C represents the comparison of interest, and O represents the outcome to be studies. The most important aspect of posing clinical questions may be that we are reminded to constantly inquire about the evidence on which our clinical actions are based. Breaking away from dominantly relying on authority and empiricism in equine medicine can only occur if we are willing to question what we think we know.


Once a clinical question has been posited, it is important to find the best available evidence by reviewing the literature. This review should be as comprehensive as possible. Relying entirely on book chapters or review articles is undesirable: new information is generated faster than it can be incorporated into textbooks, and authors of review articles have their own particular perspectives, beliefs, and perceptions that influence their interpretations and recommendations. Relying primarily on journals to which we subscribe is an inefficient way to acquire comprehensive information. Too many journals with too many articles are published each month that contain information relevant to equine practice for one to keep abreast. Furthermore, journals to which we do not subscribe or routinely access will contain important reports. For example, few equine practitioners subscribe to the journal Genomics but most if not all would have interest in reading about the mutation that causes polysaccharide storage myopathy.4

Academic institutions generally have appropriate licenses for retrieving digital/electronic publications and librarians that may assist with searching for and retrieving documents. If you lack such licenses, it may still be possible to access resources through institutions such as one's alma mater or a local college or university. Access exists to high-quality information using the Internet, using resources such as PubMed ( or BioMed Central ( These (and other) sources are freely available, but access to full articles may be limited. It is important to bear in mind that there is also much low-quality scientific information available via the Internet.