Paradigm Shifting into Evidence Based Medicine

Evidence-Based Medicine Working Group, Anonymous. Evidence-based medicine. A new approach to teaching the practice of medicine. JAMA 1992 Nov 4;268(17):2420-5.

The Former Paradigm

The former paradigm was based on the following assumptions about the knowledge required to guide clinical practice.

  • Unsystematic observations from clinical experience are a valid way of building and maintaining one's knowledge about patient prognosis, the value of diagnostic tests, and the efficacy of treatment.
  • The study and understanding of basic mechanisms of disease and pathophysiologic principles is a sufficient guide for clinical practice.
  • A combination of thorough traditional medical training and common sense is sufficient to allow one to evaluate new tests and treatment.
  • Content expertise and clinical experience are a sufficient base from which to generate valid guidelines for clinical practice.

According to this paradigm clinicians have a number of options for sorting out clinical problems they face. They can reflect on their own clinical experience, reflect on the underlying biology, go to a textbook, or ask a local expert. The "Introduction" and "Discussion" sections of a paper could be considered an appropriate way of gaining the relevant information from a current journal.

It should be noted that this paradigm puts a high value on traditional scientific authority and adherence to standard approaches, and answers are frequently sought from direct contact with local experts, or reference to the writings of international experts [19].

The New Paradigm

The assumptions of the new paradigm are as follows.

  • Clinical experience, and the development of clinical instincts (particularly with respect to diagnosis), are crucial and necessary parts of becoming a competent physician. Many aspects of clinical practice cannot, or will not, ever be adequately tested. Clinical experience, and its lessons, are particularly important in these situations. At the same time, systematic attempts to record observations in a reproducible and unbiased fashion markedly increase the confidence one can have in knowledge about patient prognosis, the value of diagnostic tests, and the efficacy of treatment. In the absence of systematic observation one must be cautious in the interpretation of information derived from clinical experience and intuition, for it may at times be misleading.
  • The study and understanding of basic mechanisms of disease are necessary but insufficient guides for clinical practice. The rationales for diagnosis and treatment which follow from basic pathophysiologic principles may in fact be incorrect, leading to inaccurate predictions about the performance of diagnostic tests and the efficacy of treatments.
  • Understanding certain rules of evidence is necessary to correctly interpret literature on causation, prognosis, diagnostic tests, and treatment strategy.

It follows that clinicians should regularly consult the original literature (and read and be able to critically appraise the "Methods" and "Results" sections) in solving clinical problems and providing optimal patient care. It also follows that clinicians must be ready to accept and live with uncertainty, and to acknowledge that management decisions are often made in the face of relative ignorance of their true impact.

The new paradigm puts a much lower value on authority [20]. The underlying belief is that physicians can gain the skills to make independent assessments of evidence, and thus evaluate the credibility of opinions being offered by experts. The decreased emphasis on authority does not imply a rejection of what one can learn from colleagues and teachers whose years of experience have provided them with insight into methods of history-taking, physical examination, and diagnostic strategies which can never be gained from formal scientific investigation. A final assumption of the new paradigm is that physicians whose practice is based on an understanding of the underlying evidence will provide superior patient care.

Requirements for the Practice of Evidence-Based Medicine

The role-modelling, practice, and teaching of evidence-based medicine requires skills that are not traditionally part of medical training. These include precisely defining a patient problem, and what information is required to resolve the problem; conducting an efficient search of the literature; selecting the best of the relevant studies, and applying rules of evidence to determine their validity [3]; being able to present to colleagues in a succinct fashion the content of the article, and its strengths and weaknesses; extracting the clinical message, and applying it to the patient problem. We will refer to this process as the "critical appraisal exercise."

Evidence-based medicine also involves applying traditional skills of medical training. A sound understanding of pathophysiology is necessary to interpret and apply the results of clinical research. For instance, most patients to whom we would like to generalize the results of randomized trials would, for one reason or another, not have been enroled in the most relevant study. The patient may be too old, be too sick, have other underlying illness, or be uncooperative. Understanding the underlying pathophysiology allows the clinician to better judge whether the results are applicable to the patient at hand. Understanding of pathophysiology also has a crucial role as a conceptual and memory aid.

A second traditional skill required of the evidence-based physician is a sensitivity to patients' emotional needs. Understanding patients' suffering [21], and how that suffering can be ameliorated by the caring and compassionate physician, are fundamental requirements for medical practice. These skills can be acquired through careful observation of patients and of physician role-models. Here too, though, the need for systematic study, and the limitations of the present evidence, must be considered. The new paradigm would call for using the techniques of behavioral science to determine what patients are really looking for from their physicians [22], and how physician and patient behavior affects the outcome of care [23]. Ultimately, randomized trials of different strategies for interacting with patients (such as the randomized trial conducted by Greenfield and colleagues that demonstrated the positive effects of increasing patients' involvement with their care [24]) may be appropriate.

Since evidence-based medicine involves skills of problem definition, searching, evaluating, and applying original medical literature, it is incumbent on residency programs to teach these skills. Understanding the barriers to educating physicians-in-training in evidence-based medicine can lead to more effective teaching strategies.