Evidence-based medicine, whose philosophical origins extend back to mid-19th century
Paris and earlier, is the conscientious, explicit and judicious use of current best
evidence in making decisions about the care of individual patients. The practice of
evidence-based medicine means integrating individual clinical expertise with the best
available external clinical evidence from systematic research. By individual clinical
expertise we mean the proficiency and judgment that we individual clinicians acquire
through clinical experience and clinical practice. Increased expertise is reflected
in many ways, but especially in more effective and efficient diagnosis and in the
more thoughtful identification and compassionate use of individual patients' predicaments,
rights, and preferences in making clinical decisions about their care. By best available
external clinical evidence we mean clinically relevant research, often from the basic
sciences of medicine, but especially from patient centered clinical research into
the accuracy and precision of diagnostic tests (including the clinical examination),
the power of prognostic markers, and the efficacy and safety of therapeutic, rehabilitative,
and preventive regimens. External clinical evidence both invalidates previously accepted
diagnostic tests and treatment and replaces them with new ones that are more powerful,
more accurate, more efficacious, and safer. Good doctors use both individual clinical
expertise and the best available external evidence, and neither alone is enough. Without
clinical expertise, practice risks becoming tyrannized by external evidence, for even
excellent external evidence may be inapplicable to or inappropriate for an individual
patient. Without current best external evidence, practice risks becoming rapidly out
of date, to the detriment of patients. The practice of evidence-based medicine is
a process of life-long, self-directed learning in which caring for our own patients
creates the need for clinically important information about diagnosis, prognosis,
therapy, and other clinical and health care issues, and in which we (1) convert these
information needs into answerable questions; (2) track down, with maximum efficiency,
the best evidence with which to answer them (whether from the clinical examination,
the diagnostic laboratory from research evidence, or other sources); (3) critically
appraise that evidence for its validity (closeness to the truth) and usefulness (clinical
applicability); (4) integrate this appraisal with our clinical expertise and apply
it in practice; and (5) evaluate our performance.