Teaching the philosophy and tools of evidence-based medicine: misunderstandings and solutions

Teaching the philosophy and tools of evidence-based medicine: misunderstandings and solutions The ProblemIn recent years, increasing emphasis has been placed on the practice of EBM.Originally proposed by Sackett and colleagues, EBM exhorts clinicians to incorporate the best available research evidence regarding efficacy and safety with individualised patient assessment and patient preferences into medical decision making (1).Figure 1 outlines the key steps in the process.Some medical schools devote a substantial amount of time to this topic (2); however, the amount of emphasis on this process of formulating questions, searching for answers, appraising the evidence, applying the results and measuring the outcome (3), is not consistent across institutions (4).Incoming residents to residency programmes thus have different exposures to this material and, more likely, have had little instruction on how to apply this in clinical practice.Clinicians trained before EBM became part of medical school curricula may be completely unaware of EBM's existence.This is particularly problematic because a wide gap exists between the best evidence and the customary practice of medicine.Clinical trials can provide a large amount of data, some of it useful in dayto-day practice, some of it not.Clinicians often struggle to find interventions that make a difference in the well-being of patients.It is often challenging to determine whether a study result should actually transform routine practice.However, there are clinically intuitive EBM tools available to help gauge clinical significance or clinical relevance, instead of focusing exclusively on whether or not a study result is statistically significant at the 'p < .05level'.Clinical significance can be quantified by calculating the effect size difference between two interventions.Effect size can be measured and compared in a variety of ways and one approach in particular is very easy to calculate and understand: NNT for potential benefit and NNH for potential harm (5).Before agreeing that a statistically significant clinical trial result is important to the clinician and patient, the NNT and NNH can be calculated to determine whether this difference will probably affect the success of day-to-day clinical practice.The magnitudes of NNT and NNH help clinicians decide whether findings that are statistically significant (e.g. at the p < 0.05 level) are also clinically relevant.Although the Accreditation Council for Graduate Medical Education requirements for a residency programme now includes competency in 'research literacy' and the 'concepts and process of Evidence Based Clinical Practice' [e.g.see psychiatry requirements (6)], there sometimes remains a misunderstanding of what is meant by EBM, with emphasis being placed on content rather than on process.Whereas some residency programmes have allocated a substantial amount of resources to teaching the process and 'philosophy' of EBM (7,8), others have not.The topic has been part of the American Society of Clinical Psychopharmacology's Model Psychopharmacology Curriculum, but in only one 'optional' lecture (9).