Evidence-based medicine: arguments for and against.

In this article I will discuss the various definitions of evidence-based medicine (EBM), and summarize the application, criticisms and limitations of EBM. The spectrum of evidence, from pathophysiological inference to randomized controlled trials, will be presented as a mechanism for filtering bias with more rigorous evidence being required when bias is more likely. Although randomized controlled trials and meta-analyses are at the top of the evidence hierarchy, they are not always necessary, might not be the most appropriate forms of evidence for some clinical questions, and have their own limitation that need to be understood. Best available evidence, applied to individual patients, is the corner stone of EBM. Although there are valid criticisms and limitations of EBM, if these are understood then the practice of EBM can provide guidance to the clinician and enhance patient care.