The need for evidence-based medicine
At the Annual General Meeting of Health Watch at Regent College, London this year we were delighted to welcome guest speaker Professor David Sackett from the Oxford Radcliffe Hospital. The professor's compelling talk described his team's important work on the need for accurate and up-to-date information in making clinical decisions.
Doctors need new clinical information up to 100 times a week but are unlikely to receive it because their textbooks are out of date, and their journals disorganised. Yet this dearth of accurate information could influence eight important decisions every day. So began Professor David Sackett, visiting professor at the University of Oxford, when he addressed the 7th Annual General Meeting of HealthWatch on 23rd October 1995.
By questioning a group of general practitioners while they saw their patients, Professor Sackett's team identified up to 16 needs for new, clinically-important information in just half a day, of which a quarter were related to diagnosis.
However, only 30% of these information needs were met in the doctor's workplace, and most of these by asking colleagues.
The literature shows that doctors' ability to obtain the information they need is limited by out-of-date textbooks, journals that are too disorganised to be useful, and by simply not having enough time to read. Even the keenest GPs spend only one hour a week reading the medical literature, and this is clearly not enough to keep pace with therapeutic advances.
The net effect of this unfulfilled need for important new information is that it can lead to progressive declines in clinical competency. It has been shown repeatedly that there is a negative correlation between a doctors' knowledge of up to date care and the years that have elapsed since completing formal training. For example, in one study of clinical behaviour, the decision to start antihypertensive drugs was more closely linked to the number of years since medical school graduation in the doctor than to the severity of target organ damage in the patient.
It is clear, said Professor Sackett, that doctors need far readier access to clinically-important information. The problem is to distill the message buried in some 600,000 published randomised controlled trials into a form which was accessible to clinicians when they needed it, and on which they would be able to base their treatment decisions.
Critics of conventional medicine, said the professor, have claimed that fewer than 15% of medical interventions are supported by solid scientific evidence, leaving between 80 and 90% in the realms of quackery. A more reassuring picture emerged when the professor’s team reviewed the diagnoses made and interventions performed upon 121 patients admitted during April 1995 to the John Radcliffe Hospital.
He found that the vast majority - 82% - of interventions were justified on the basis of evidence-based medicine, and in 53% of all cases that evidence came from randomised controlled trials. In only 18% of cases were treatments were performed for which there was not substantial clinical evidence, and Professor Sackett found that these involved mainly non-acute disorders for which there are no known effective treatments.
The professor went on to outline how clinicians can practice evidence-based medicine for themselves as a life-long, self-directed learning process. The discipline involves:
- converting information needs into answerable questions;
- tracking down efficiently the best evidence with which to answer them;
- critically appraising that evidence for its validity and usefulness;
- applying the results and evaluating performance.
Research in Canada has shown that when equipped with these skills, graduates not only made more accurate diagnostic and management decisions, but they retained a high level of clinical competence and stayed more up to date than their traditionally trained peers as long as 15 years after graduation.
After his talk at the HealthWatch 7th Annual General Meeting Mr Nick Ross announced that Professor David Sackett was the unanimous choice of the committee for the Third Annual HealthWatch Award. Professor Sackett was presented with a handsome silver-plate comport-a dish for dessert, raised on a stem-inscribed with these words:
To Professor David Sackett in recognition of his distinguished contributions to medical research, education and the reliable assessment of treatment.