Evidence-based Health Care

David Sackett's definition of 'evidence based medicine' (EBM) is now well known and widely accepted. But the phrase 'evidence based health care' (EBHC) is rarely defined. Much of my work involves explaining and trying to apply the principles of EBM and EBHC, often to people who have been puzzled and even irritated by what they had thought EBM and EBHC implied about their current and past practice. I have evolved my explanation of EBHC into a definition:

"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.


Other things follow from this definition, not least that the concept of EBHC is not new - it's what most people I know have been trying to practice all their working lives. But there are new reasons and new opportunities to help us improve the care that patients receive including:

  1. more and better information e.g. from the increasing number of well conducted RCTs and systematic reviews,
  2. the better organisation of information and new insights that derive from the evolving science of systematic review,
  3. rapid advances in information technology and
  4. an improving (though still inadequate) understanding of the (social and organisational) processes by which research findings are translated into practice.


I have been using this definition for a year or so now. People seem to find it useful and non-threatening. I would value the thoughts and any suggestions for improving it from readers of Bandolier .

Dr Nicholas Hicks

Department of Public Health and Health Policy

Oxfordshire Health Authority

Fax: +44 1865 226894

email: nicholas.hicks@dphpc.ox.ac.uk  

http://www.jr2.ox.ac.uk/bandolier/band39/b39-9.html