Evidence-Based Medicineの意義と限界-疫学の立場から-

抄録

Evidence based medicine (EBM) was proposed by Guyatt in the early 1990s. Sackett and colleagues have established basic concept of EBM. They defined that EBM was the conscientious, explicit, and judicious use of current best evidence in making clinical decisions for each patient. Recently, although many clinicians recognized epidemiology as an importance tool for EBM, there were some misunderstandings in the decision-making process to use evidence level. Some clinicians believe EBM must need randomized-controlled trials (RCT). However, RCT is not always best available evidence. RCT is not suitable to examine harmful exposures, such as smoking, due to ethical problems. Furthermore, to clarify very week association, such as dietary habit and stroke, RCT requires too huge sample size to perform practically. When we are looking for second best evidence, the consistency is a main target. For example, cohort studies anywhere on the globe showed the positive relationship between smoking and cerebral infarction. Although EBM is substantially made to resolve a one-on-one clinical relationship (one therapy and one outcome), clinical questions usually consist of more complex matters with many-to-many, many-to-one, one-to-many associations. We should combine the best available external evidence with our clinical expertise, and neither alone may work enough.