Animals in Scientific Research
Science of the Future - Evidence-based Medicine
A somewhat recent development in medicine is what is called evidence-based medicine or EBM. One definition is:
Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research. Because the randomized trial, and especially the systematic review of several randomized trials, is so much more likely to inform us and so much less likely to mislead us, it has become the “gold standard” for judging whether a treatment does more good than harm.
Some say that good doctors have been using EBM for ages but as a formal method of study it is new.
Medical evidence has historically been ranked in order of reliability as follows:
- Evidence obtained from at least one properly randomized controlled trial.
- Evidence obtained from well-designed controlled trials without randomization.
- Evidence obtained from well-designed cohort or case-control analytic studies, preferably evidence obtained from multiple time series with or without intervention. Dramatic results in uncontrolled experiments (such as the results of the introduction of penicillin treatment in the 1940s) could also be regarded as this type of evidence.
- Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees.
The following is from the Oxford Centre for Evidence-Based Medicine:
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. 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.
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 judgment will be better, faster clinicians than their peers.
There are many questions in medicine to which we have no answer because the research needed to answer the question has not been performed or there are conflicting studies. EBM seeks to point out what we don’t know, what we do know and how confident we should be in that knowledge. Systematic reviews are providing us with data when we have conflicting studies or no consensus on the issue. If patients are to receive the best that medical care has to offer then EBM must be incorporated into every physician’s routine and it must be expanded. Studies must be done to determine what the best options are and this will be a very large undertaking. But this is the kind of research that must be done if medicine is to advance.
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