This page summarised some of the reasons why we need EBM. It addresses:
- The emergence of new types of evidence which can change the way we treat patients
- The fact that although we need this evidence daily, we don't get it
- The resultant deterioration in the currency of our clinical knowledge
- Traditional approaches to medical education don't solve this problem
- An alternative approach has been shown to help
In selecting treatments for patients, until recently it had been considered sufficient to understand the pathophysiological process in a disorder and to prescribe drugs or other treatments that had been shown to interrupt or modify this process.
For example, the observation that patients with ventricular ectopic beats following myocardial infarction were at high risk of sudden death [1]. However, subsequent randomised controlled trials examined hard clinical outcomes, not physiologic processes, and showed that several of these drugs increase, rather than decrease, the risk of death in such patients, and their routine use is now strongly discouraged [2].
Other randomised trials (their total number now between 250,000 and 1,000,000!) have confirmed the efficacy of many treatments and confirmed the uselessness or harmfulness of many others. And a still more recent methodology, the systematic review or overview (when it uses specific sorts of statistics it’s called a meta-analysis) has permitted us to draw even firmer conclusions by combining all the proper randomised trials on an issue in health care.
Equally powerful methods have been developed and applied to determine the validity and usefulness of the clinical history and physical examination, diagnostic tests, and prognostic markers. For example, there are more than 30 bits of the history and physical examination that we could pursue (and often are taught to do so!) in deciding whether a patient had chronic airflow limitation. But when these bits are subjected to rigorous evaluation for their precision and accuracy, the emerging evidence reveals that most of them either bear no relation to simultaneous physiological measurements (such as peak flows or FEV1 ) or can’t be confirmed on repeat examination, even by the same clinician! The bottom line is that there are some specific items of the history and physical exam that are very precise and accurate in the bedside diagnosis of chronic airflow limitation, and clinicians who know them and can integrate them with their other knowledge and judgement will be better, faster clinicians than their peers.
Clinicians who keep up to date with these advances in knowledge practice better medicine. Unfortunately, most of us don’t. Given the extremely rapid growth of randomised trials and other rigorous clinical investigations, the issue is no longer how little of medical practice has a firm basis in such evidence; the issue today is how much of what is firmly based is actually applied in the front lines of patient care.
A study of North American general physicians found that they reported a need for new and clinically important information just once or twice a week. However, subsequent "shadowing" and direct questioning of the same group revealed two such information needs for every three new patients they saw. [3] The clinicians cited three main barriers between them and the information they needed:
- lack of time
- out-of-date textbooks, and
- the disorganisation of the up-to-date journals.
The clinical literature is now so big that general physicians who want to keep abreast of the journals relevant to their practices have to examine 19 articles a day, 365 days a year [4]. Even self-reports of median reading times shown that there is simply no way that clinicians have enough time to read all the journals relevant to them. The table below summarises Dave Sackett's polls of medical grand rounds audiences at a number of UK medical schools:
| How many minutes did you spend last week reading around your patients? | ||
| Stage of Career | Range of median reading times | % who reported NO reading in the last week |
| Medical students | 60-120 min | 0% |
| House officers | 0-20 min | up to 75% |
| Senior house officers | 10-30 min | up to 15% |
| Registrars | 10-90 min | up to 40% |
| Senior registrars | 10-45 min | up to 15% |
| Consultants graduating since 1975 | 15-60 min | up to 30% |
| Consultants graduating pre-1975 | 10-45 min | up to 40% |
| When our competency is measured by our knowledge of even the basics of the care of disorders like hypertension, as revealed in the figure (right), it has been shown repeatedly that there is a statistically and clinically significant negative correlation between our knowledge of up to date care and the years that have elapsed since our graduation from medical school [5,6]. Moreover, in a Canadian study of actual clinical behaviour, the decision to start antihypertensive drugs was better predicted by the number of years since medical school graduation in the doctor (most were graduates of North American or UK medical schools) than it was by the severity of target organ damage in the patient [7]. |  |
It is clear from the foregoing that we need far readier access to clinically important information. No wonder, then, that there is increasing interest in providing, and even requiring, Continuing Medical Education (CME), Continuing Professional Development, and the like. But when the same powerful strategy for determining the efficacy of a therapeutic regimen - the randomised controlled trial - has been used to test the efficacy of CME, the results have been sobering. Systematic reviews of the relevant randomised trials have shown that traditional, instructional CME simply fails to modify our clinical performance and is ineffective in improving the health outcomes of our patients [8,9].
| There is some evidence that
problem-based approaches to medical education equip us better to keep
up-to-date with clinical research. The diagram on the right summarises a
study comparing the currency of knowledge of graduates of a
problem-based curriculum (McMaster) with those of a traditional
curriculum (Toronto) [8]. More recently, significant steps have been taken to improve the accessibility, relevance and usability of the evidence base. You can see some examples of these "evidence-based summaries" in publications such as: Recently, the UK's National electronic Library for Health has made significant progress towards assembling the most important of these resources on one portal. |
 |
- Morganroth J, Bigger JT Jr, Anderson JL: Treatment
of ventricular arrhythmia by United States cardiologists: a survey before
the Cardiac Arrhythmia Suppression Trial results were available. Am J
Cardiol 1990;65:40-8.
- Echt DS, Liebson PR, Mitchell B, et al: Mortality
and morbidity in patients receiving encainide, flecainide, or placebo: The
Cardiac Arrhythmia Suppression Trial. N Engl J Med 1991;324:781-8.
- Covell DG, Uman GC, Manning PR: Information needs
in office practice: Are they being met? Ann Intern Med 1985;103:596-9.
- Davidoff F, Haynes B, Sackett D, Smith R: Evidence
based medicine: a new journal to help doctors identify the information
they need. BMJ 1995;310:1085-6.
- Ramsey PG, Carline JD, Inui TS et al: Changes over
time in the knowledge base of practicing internists. JAMA 1991;266:1103-7.
- Evans CE, Haynes RB, Birkett NJ et al: Does a
mailed continuing education program improve clinician performance? Results
of a randomised trial in antihypertensive care. JAMA 1986:255:501-4.
- Sackett DL, Haynes RB, Taylor DW, Gibson ES, Roberts RS, and Johnson AL. Clinical determinants of the decision to treat primary hypertension. Clinical Research 1977;24:648.
- Shin JH. Haynes RB. Johnston ME. Effect of
problem-based, self-directed undergraduate education on life-long
learning. Canadian Medical Association Journal 1993; 148(6):969-76).
- Davis DA, Thompson MA, Oxman AD, Haynes RB:
Changing physician performance. A systematic review of the effect of
continuing medical education strategies. JAMA 1995;274:700-5.
- Sibley JC, Sackett DL, Neufeld V, et al: A randomised trial of continuing medical education. N Engl J Med 1982;306:511-5.