Preparing for Evidence-based Medicine

Masoud Rahimian

When did EBM begin ?

Certainly in post-revolutionary Paris.

Arguably in B.C China.

Some late-comers named it in 1992.

Evidence-based medicine. A new approach to teaching the practice of medicine. Evidence-Based Medicine Working Group

JAMA. 1992;268(17):2420-2425

rapid spread of EBM has arisen from 4 realizations

1-Our daily need for valid information about diagnosis, prognosis, therapy and prevention (up to 5 times per in-patient and twice for every 3 out-patients).

2-The inadequacy of traditional sources for this information because they are out-of-date (textbooks), frequently wrong (experts), ineffective (didactic continuing medical education) or too overwhelming in their volume and too variable in their validity for practical clinical use (medical journals).

3- The disparity between our diagnostic skills and clinical judgement, which increase with experience, and our up-to-date knowledge and clinical performance which decline.

4- our inability to afford more than a few seconds per patient for finding and assimilating this evidence or to set aside more than half an hour per week for general reading and study.

This workshop is devoted to describing these innovations, demonstrating their application to clinical problems, and showing how they can be learned and practiced by clinicians who have just 30 minutes per week to devote to their continuing professional development.

Until recently, these problems were insurmountable for full-time clinicians. However, 5 developments have permitted us to turn this state of affairs around:

1-The development of strategies for efficiently tracking down and appraising evidence (for its validity and relevance)

2-The creation of systematic reviews and concise summaries of the effects of health care (epitomized by the Cochrane Collaboration

The Problems:

We need evidence (about the accuracy of diagnostic tests, the power of prognostic markers, the comparative efficacy and safety of interventions, etc.) about 5 times for every in-patient (and twice for every 3 out-patients).

We get less than a third of it

The Problems:

To keep up to date in Internal Medicine, I need to read 17 articles a day, 365 days a year

Need to readDon’tNor does anyone else

3-The creation of evidence-based journals of secondary publication (that publish the 2% of clinical articles that are both valid and of immediate clinical use).

4-The need for creation of information systems for bringing the foregoing to us in seconds

Performance deteriorates, too

Determinants of the clinical decision to treat some, but not other, hypertensives:

1 Level of blood pressure.2 Patient’s age.3 The physician’s year of graduation from

medical school.4 The amount of target-organ damage.

No wonder, then, that CME is growing

Big, and getting huge.Usually instructionally (fact) oriented. Several randomised trials have shown that it

does not improve clinical performance.

5-The identification and application of effective strategies for life-long learning and for improving our clinical performance.

The growing database of pre-appraised resources is making this “searching” mode more and more feasible for busy clinicians

How do we actually practice EBM?The full-blown practice of EBM comprises 4

steps, and this workshop takes them up in turn:

Step 1: Converting the need for information (about prevention, diagnosis, prognosis, therapy, causation, etc) into an answerable question

Step 2: Tracking down the best evidence with which to answer that question

Step 3: Critically appraising that evidence for its validity (closeness to the truth), impact (size of the effect), and applicability (usefulness in our clinical practice)

Step 4: Integrating the critical appraisal with our clinical expertise and with our patient’s unique biology, values and circumstances

Information “pull”Steps in EBM process

1. Formulate an answerable question

2. Track down the best evidence

3. Critically appraise the evidence

4. Integrate with clinical expertise and patient values

For the conditions we encounter every day (e.g., unstable angina and venous thromboembolism) we need to be “up-to-the-minute” and very sure about what we are doing

For the conditions we encounter less often (e.g., temporal arteritis, aspirin poisoning), we conserve our time by seeking out critical appraisals already performed by others who describe (and stick to!) explicit criteria for deciding what evidence they selected and how they decided whether it was valid

For the problems we’re likely to encounter very Infrequently we “blindly” seek, accept and apply the recommendations we receive from authorities in the relevant branch of medicine. The trouble with the “replicating” mode is that it is “blind” to whether the advice received from the experts is authoritative (evidence-based, resulting from their operating in the “appraising” mode) or merely authoritarian (opinion-based, resulting from pride and prejudice)