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About Evidence

"Evidence based health care takes place when decisions that affect the care of patients are taken with due weight accorded to all valid, relevant information."

Several things follow from this definition:

  1. 'decisions that affect the care of patients'are taken by managers and health policy makers as well as by clinicians. EBHC is therefore just as relevant to managers and policy makers as it is to clinicians.
  2. 'due weight' implicitly acknowledges that there are many factors that contribute to decisions about the care of patients. There are many factors other than the results of randomised controlled trials that may weigh heavily in both clinical and policy decisions (for instance, patient preferences and resources). This definition requires that valid, relevant evidence should be considered alongside other relevant factors in the decision making process. It does not assume that any one sort of evidence should necessarily be the determining factor in a decision.
  3. 'all' is aspirational - but it implies that there should be an active search for valid, relevant information
  4. 'valid, relevant' implies that before information is used in a decision, an assessment should be made of the accuracy of the information and the applicability of the evidence to the decision in question; that is, information should be appraised.
  5. 'information' is deliberately left unspecified; there are many types of information that may be valid and relevant in particular circumstances. I have no wish to exclude any particular type of information as long as an appraisal is made of its validity and relevance and the information is given 'due weight' - neither more nor less.

Reference:Evidence based healthcare - a definition by Dr Nicholas Hicks, published in Bandolier (1997).

"Evidence based medicine 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 judgement that 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 centred 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 treatments and replaces them with new ones that are more powerful, more accurate, more efficacious, and safer." 

Source: Sackett, D.L. et al. (1996) Evidence based medicine: what it is and what it isn't. BMJ 312 (7023), 13 January, 71-72).