Evidence-Based Medicine:
What It Is and What It Isn't

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:    Frankp@chiro.org

This article is an editorial from
British Medical Journal 1996 (Jan 13); 312 (7023): 71–72 ~ FULL TEXT

David L Sackett, William MC Rosenberg, JA Muir Gray, R Brian Haynes, W Scott Richardson

Contents:

• Core definition of Evidence-Based Medicine
  
  
• What Evidence-Based Medicine isn't
  
  
• References

Evidence-Based Medicine, whose philosophical origins extend back to mid-19th century Paris and earlier, remains a hot topic for clinicians, public health practitioners, purchasers, planners, and the public. There are now frequent workshops in how to practice and teach it (one sponsored by this journal will be held in London on April 24th); undergraduate [1] and post-graduate training programmes [2] are incorporating it [3] (or pondering how to do so); British centres for evidence-based practice have been established or planned in adult medicine, child health, surgery, pathology, pharmacotherapy, nursing, general practice, and dentistry; the Cochrane Collaboration and the York Centre for Review and Dissemination in York are providing systematic reviews of the effects of health care; new evidence-based practice journals are being launched; and it has become a common topic in the lay media. But enthusiasm has been mixed with some negative reaction [4-6]. Criticism has ranged from evidence-based medicine being old-hat to it being a dangerous innovation, perpetrated by the arrogant to serve cost-cutters and suppress clinical freedom. As evidence-based medicine continues to evolve and adapt, now is a useful time to refine the discussion of what it is and what it is not.

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. By individual clinical expertise we mean the proficiency and judgement that individual clinicians acquire through clinical experience and clinical practice. Increased expertise is reflected in many ways, but especially in more effective and efficient diagnosis and in the more thoughtful identification and compassionate use of individual patients' predicaments, rights, and preferences in making clinical decisi ons about their care. By best available external clinical evidence we mean clinically relevant research, often from the basic sciences of medicine, but especially from patient centred clinical research into the accuracy and precision of diagnostic tests (including the clinical examination), the power of prognostic markers, and the efficacy and safety of therapeutic, rehabilitative, and preventive regimens. External clinical evidence both invalidates previously accepted diagnostic tests and treatments and replaces them with new ones that are more powerful, more accurate, more efficacious, and safer.

Good doctors use both individual clinical expertise and the best available external evidence, and neither alone is enough. Without clinical expertise, practice risks becoming tyrannised by evidence, for even excellent external evidence may be inapplicabl e to or inappropriate for an individual patient. Without current best evidence, practice risks becoming rapidly out of date, to the detriment of patients.

This description of what evidence-based medicine is helps clarify what evidence-based medicine is not. Evidence-based medicine is neither old-hat nor impossible to practice. The argument that everyone already is doing it falls before evidence of striking variations in both the integration of patient values into our clinical behaviour [7] and in the rates with which clinicians provide interventions to their patients [8]. The difficulties that clinicians face in keeping abreast of all the medical advances reported in primary journals are obvious from a comparison of the time required for reading (for general medicine, enough to examine 19 articles per day, 365 days pe r year [9]) with the time available (well under an hour per week by British medical consultants, even on self-reports [10]).

The argument that evidence-based medicine can be conducted only from ivory towers and armchairs is refuted by audits in the front lines of clinical care where at least some inpatient clinical teams in general medicine [11], psych iatry (JR Geddes, et al, Royal College of Psychiatrists winter meeting, January 1996), and surgery (P McCulloch, personal communication) have provided evidence-based care to the vast majority of their patients. Such studies show that busy clinici ans who devote their scarce reading time to selective, efficient, patient-driven searching, appraisal and incorporation of

Evidence-based medicine is not "cook-book" medicine.   Because it requires a bottom-up approach that integrates the best external evidence with individual clinical expertise and patient-choice, it cannot result in slavish, cook-book appr oaches to individual patient care. External clinical evidence can inform, but can never replace, individual clinical expertise, and it is this expertise that decides whether the external evidence applies to the individual patient at all and, if so, how it should be integrated into a clinical decision. Similarly, any external guideline must be integrated with individual clinical expertise in deciding whether and how it matches the patient's clinical state, predicament, and preferences, and thus whether i t should be applied. Clinicians who fear top-down cook-books will find the advocates of evidence-based medicine joining them at the barricades.

Evidence-based medicine is not cost-cutting medicine.   Some fear that evidence-based medicine will be hijacked by purchasers and managers to cut the costs of health care. This would not only be a misuse of evidence-based medicine but suggests a fundamental misunderstanding of its financial consequences. Doctors practising evidence-based medicine will identify and apply the most efficacious interventions to maximise the quality and quantity of life for individual patients; this may raise rather than lower the cost of their care.

Evidence-based medicine is not restricted to randomised trials and meta-analyses.   It involves tracking down the best external evidence with which to answer our clinical questions. To find out about the accuracy of a diagnostic test, we need to find proper cross-sectional studies of patients clinically suspected of harbouring the relevant disorder, not a randomised trial. For a question about prognosis, we need proper follow-up studies of patients assembled at a uniform, early point in the clinical course of their disease. And sometimes the evidence we need will come from the basic sciences such as genetics or immunology. It is when asking questions about therapy that we should try to avoid the non-experimental approaches, since these routinely lead to false-positive conclusions about efficacy. Because the randomised trial, and especially the systematic review of several randomised 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. However, some questions about therapy do not require randomised trials (successful interventions for otherwise fatal conditions) or cannot wait for the trials to be conducted. And if no randomised trial has been carried out for our patient’s predicament, we follow the trail to the next best external evidence and work from there.

Despite its ancient origins, evidence-based medicine remains a relatively young discipline whose positive impacts are just beginning to be validated [12, 13], and it will continue to evolve. This evolution will be enhanced as seve ral undergraduate, post-graduate, and continuing medical education programmes adopt and adapt it to their learners’ needs. These programmes, and their evaluation, will provide further information and understanding about what evidence-based medicine is, and what it is not.

Authors:

• David L. Sackett, Professor, NHS Research and Development Centre for Evidence-Based Medicine, Oxford.

• William M. C. Rosenberg, Clinical Tutor in Medicine, Nuffield Department of Clinical Medicine, Oxford.

• J. A. Muir Gray, Director of Research and Development, Anglia and Oxford Regional Health Auhtority, Milton Keynes

• R. Brian Haynes, Professor of Medicine and Clinical Epidemiology, McMaster University Hamilton, Canada

• W. Scott Richardson, Rochester, USA

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References:

1. British Medical Association:
   Report of the working party on medical education.
   London: British Medical Association, 1995.

2. Standing Committee on Postgraduate Medical and Dental Education:
   Creating a better learning environment in hospitals:
   1.Teaching hospital doctors and dentists to teach.
   London: SCOPME, 1994.

3. General Medical Council:
   Education Committee Report.
   London: General Medical Council, 1994.

4. Grahame-Smith D:
   Evidence-based medicine: Socratic dissent.
   BMJ 1995;310:1126-7.

5. Evidence-based medicine, in its place (editorial).
   Lancet 1995;346:785.

6. Correspondence. Evidence-Based Medicine.
   Lancet 1995;346:1171-2.

7. Weatherall DJ:
   The inhumanity of medicine.
   BMJ 1994;308:1671-2.

8. House of Commons Health Committee.
   Priority setting in the NHS: purchasing. First report sessions 1994-95.
   London: HMSO, 1995, (HC 134-1.)

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.

10. Sackett DL:
    Surveys of self-reported reading times of consultants in Oxford, Birmingham, Milton-Keynes,
    Bristol, Leicester, and Glasgow, 1995.
    In Rosenberg WMC, Richardson WS, Haynes RB, Sackett DL.
    Evidence-Based Medicine. London: Churchill -Livingstone (in press).

11. Ellis J, Mulligan I, Rowe J, Sackett DL:
    Inpatient general medicine is evidence based. Lancet 1995;346:407-10.

12. Bennett RJ, Sackett DL, Haynes RB, Neufeld VR: A controlled trial of teaching critical appraisal of the clinical literature to medical students. JAMA 1987;257:2451-4.

13. Shin JH, Haynes RB, Johnston ME: Effect of problem-based, self-directed undergraduate education on life-long learning. Can Med Assoc J 1993;148:969-76.

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