There are many different definitions of evidence based medicine. One of the most comprehensive definitions was created by the Journal of the American Medical Association (JAMA) and adopted by the National Library of Medicine (NLM) for it's Medical Subject Headings (MeSH).
An approach of practicing medicine with the goal to improve and evaluate patient care. It requires the judicious integration of best research evidence with the patient's values to make decisions about medical care. This method is to help physicians make proper diagnosis, devise best testing plan, choose best treatment and methods of disease prevention, as well as develop guidelines for large groups of patients with the same disease. [JAMA v.296(9), 2006]
There are three fundamental principles of EBM that should provide guidance in the practice of evidence based medicine.
Working to find the optimal clinical decision for a patient's case based on awareness of best available evidence.
Evaluating evidence levels and heirarchy to accurately assess and select the best theraputic option according to the evidence. While evidence is neccessary, it is not the only factor to evaluate; there may be times when a clinician's experience or a patient's values or preferences will carry more weight than the available evidence.
Considering the patient's unique case, values and perferences to evaluate the risks and benefits of the selected treatement, assess any additional burdens or costs that may be placed on the patient, and evaluate possible alternative treatments.
Evidence based medicine in clinical practice consists of four general steps: asking a question, collecting relevant information, evaluating the gathered evidence, and implementing the results in everyday clinical practice. However, quickly and accurately implementing these steps in a clinical setting can take some practice.