What is Evidence-Based Medicine?

The words “evidence-based” are used to describe lots of things in medicine, healthcare and beyond. Evidence-based medicine (EBM), evidence-based practice, evidence-based policy, and – in a different part of society – evidence-based social work and evidence-based education.

The underlying principals are the same. The concept is about making sure that when decisions are made they are made on the basis of the most up-to-date, solid, reliable, scientific evidence. In the case of medicine or health care, these are the decisions about the care of individual patients.

A simple definition from 1996 is:

"Evidence-based medicine is the conscientious explicit and judicious use of current best evidence in making decisions about the care of individual patients." [1]

What is the best decision?

Every part of this sentence is important. Consider the words themselves:

What sort of evidence are we looking for? “Current best evidence”. Not perfect evidence – simply, the best there is. But not old or out-of-date evidence; we need to find modern, up-to-date current evidence.

How is this to be done? In a conscientious, explicit and judicious way. Again, the words are important.

Conscientious – being careful, and thorough, in what you do

Explicit – being “up-front”, open, clear and transparent

Judicious – using good judgement and common sense

If you are going to practice in this way, you have to be able to find evidence from scientific studies that are relevant to your patients. You then have to understand those studies and be able to appraise them (not all studies will be relevant to your patient and even if they are, they may not be good studies). And finally you have to apply those results when making decisions about your patient. This means being able to integrate the evidence with your patients personal needs, their values and beliefs and their wishes.

So an alternative definition of evidence-based practice would be:

"Evidence-based practice is the conscientious explicit and judicious use of current best evidence in helping individual patients make decisions about their care in the light of their personal values and beliefs"


EBM in real life practice


Are you asking the right questions?

If EBM is about using the best information to make decisions, how is it actually practiced? It’s about asking the right questions and using the best research evidence to answer those questions.  Sometimes when a patient has a condition that is very rare or unusual there is very little high-quality information to be found. To do the best for the patient, you may need to rely on a good understanding of anatomy, physiology and pathology and work out what’s best “from first principles”. At other times, you rely on the experience of older and wiser colleagues.

Sometimes there are hundreds of clinical studies involving hundreds, or even thousands of patients, and those studies all have similar results. That makes advising the patient on the benefits of treatment relatively easy. On the other hand, what if the results of different studies are conflicting? Or the studies didn’t look at the sort of patients you are treating.

Evidence-based medicine is about making use of the best available information to answer questions in clinical practice. Questions may be simple: does drinking tea reduce your blood pressure? Or complex: what is the best treatment to improve the vision of elderly diabetic patients with macular degeneration? The principles of EBM allow you to find and evaluate the information available, assess its reliability and decide if you can apply the results to your patients.

Is EBM time-consuming and difficult? No – it need not be. There are many EBM resources where much of the work has been done for you.  What is more important is that you understand the philosophy underpins EBM and are “signed up” to it. You might ask yourself this question; when I am a patient, do I want to benefit from current best evidence, applied conscientiously, explicitly or judiciously? Or do I want something less?

For a more comprehensive introduction to EBM, click here for a list of the latest resources on EBM on this site.

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[1] David Sackett, William Rosenberg, Muir Gray, Brian Haynes & Scott Richardson. Evidence based medicine: what it is and what it isn’t [internet]. BMJ; 13 January 1996 [cited 23 May 2013]. Available from: http://www.bmj.com/content/312/7023/71

[2] Imogen Evans, Hazel Thornton & Iain Chalmers. Testing Treatments: Better research for better healthcare [Internet]. Testing Treatment Interactive; 2010 [cited 07 July 2015]. Available from: http://www.testingtreatments.org/book/