Education and debate

Ethics and evidence based medicine

Ian Kerridge, clinical lecturer, ^a Michael Lowe, clinical tutor, ^a David Henry, professor of clinical pharmacology. ^b

^a Clinical Unit in Ethics and Health Law, Faculty of Medicine and Health Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia, ^b Faculty of Medicine and Health Sciences, University of Newcastle

Correspondence to: Dr I Kerridge, John Hunter Hospital, Locked Bag No 1, Newcastle Mail Region Centre, NSW 2310, Australia

Evidence based medicine is founded upon an idealthat decisions about the care of individual patients should involve the "conscientious, explicit and judicious use of current best evidence."¹ Several publications are dedicated to evidence based medicine, and, at an international level, the Cochrane Collaboration has been formed to gather, analyse, and disseminate evidence derived from published research.² Several practical approaches to evidence based medicine in clinical decision making have also been described. ^{3 4}

Evidence based medicine, it is claimed, leads to improvements in clinicians' knowledge, reading habits, and computer literacy; provides a framework for teaching; enables junior team members to contribute to decisions; and allows better communication with patients and more effective use of resources.⁵ From an ethical perspective, the strongest arguments in support of evidence based medicine are that it allows the best evaluated methods of health care (and useless or harmful methods) to be identified and enables patients and doctors to make better informed decisions. ^{5 6}

However, the presence of reliable evidence does not ensure that better decisions will be made. Claims that evidence based medicine offers an improved method of decision making are difficult to evaluate because current practice is so poorly defined. Medical decision making draws upon a broad spectrum of knowledgeincluding scientific evidence, personal experience, personal biases and values, economic and political considerations, and philosophical principles (such as concern for justice). It is not always clear how practitioners integrate these factors into a final decision, but it seems unlikely that medicine can ever be entirely free of value judgments.

We review ethical concerns associated with evidence based medicinein particular that it invites a simplistic approach to the role of evidence in medicine, which can be misinterpreted and may not allow for the complexity of clinical decision making.

	The philosophical basis

Evidence based medicine represents a practical example of consequentialismthe proposition that the worth of an action can be assessed by the measurement of its consequences. Criticisms of consequentialist philosophies may be considered under three main headings. Firstly, many important outcomes cannot be adequately measured or defined. Secondly, it is often unclear whose interests should be considered in determining outcomes. Thirdly, consequentialism may lead to conclusions that are thought to be unethical from other points of view. These criticisms may equally apply to evidence based medicine.

Immeasurable outcomes
The first philosophical criticism of evidence based medicine is that many important outcomes of treatment cannot be measured. This arises from the fact that evidence based medicine claims to provide a simple, logical process for reasoning and decision makinglook at the evidence and decide accordingly. But to make balanced decisions, all the relevant consequences of an action must be considered. Unfortunately, current measures of some outcomes of medical treatment (such as pain) are inadequate; some (such as justice) may not be measurable; and other complex outcomes (such as quality of life) may not even be adequately definable. ^{7 8}

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Deciding between competing claims
The second philosophical criticism, that it may be impossible to decide between competing claims of different stakeholders, is emphasised by the manner in which patients continue to have little influence over the priorities of research. Evidence based medicine claims to reject the power of expert opinion but it is still mostly doctors who determine research objectives, who interpret research data, and who implement research findings. A number of commentators have called for greater involvement by consumer groups in setting research agendas, but how conflicts between the agendas of the different stakeholders are to be resolved remains unclear. ^{10 11} Evidence based medicine is unable to address political concerns because the values of different stakeholders, and hence the way in which they interpret evidence, cannot always be made congruent with each other.

At odds with common morality
The third philosophical criticism, that evidence based medicine may lead to activities that seem at odds with common morality, arises from the fact that evidence based medicine assesses interventions solely in terms of evidence of efficacy. An example of the difficulties that may arise from this approach occurs in the field of meta-analysis. Researchers performing meta-analyses are generally urged to search as widely as possible for data and to use unpublished studies if they are methodologically sound. However, valuable research findings may arise from unethically conducted research and data from unpublished studies may not meet the ethical safeguards that are demanded by publishers. In such cases it may be unclear whether results should be used or discarded.

	Collecting evidence

Randomised controlled trials
Proponents of evidence based medicine emphasise the value of some forms of evidence over others, placing particular emphasis upon the results of randomised controlled trials.¹⁷ For example, the United States Preventive Services Taskforce rates the value of evidence from randomised controlled trials as "grade I," evidence from non-randomised trials as "grade II," and evidence from the opinions of respected authorities as "grade III."¹⁸

Ethical concerns
Randomised controlled trials have the potential to prevent the propagation of worthless treatments and confirm the value of effective treatments. They raise a number of issues that cause ethical concern, including: the selection of subjects, consent, randomisation, the manner in which trials are stopped, and the continuing care of subjects once the trials are complete.

"Therapeutic equipoise"
The administration of randomised controlled trials requires doctors and patients to balance the requirements of several distinct rolesdoctors may act simultaneously as physicians and research scientists, and patients as invalids and research subjects. It has been suggested that physicians' moral responsibilities towards their patients are inconsistent with any recommendation that the patients should participate in randomised controlled trials because of this conflict of interest. ^{19 20} However, it is held that doctors may recommend that their patients participate if they are in a state of "therapeutic equipoise"that is, there is genuine doubt about the value of different interventions.²¹

	Using evidence

Individual care and resource allocation
Clinical trials seem the best basis for clinical decision making. However, compared with other topics in evidence based medicine, the techniques for accurate application of trial results have received scant attention. There is a widely held view that the correct approach is through a comparison of the trial subjects and the population to which the results are to be applied.²³ This is not necessarily so, as the overall results of a trial represent an average effect, and even within the trial population some will experience a greater than average improvement in outcomes, while others may suffer harm. ^{24 25} Consequently, although crude applications of trial results may on average do more good than harm, they may none the less disadvantage some patients.

Systematic bias
Governments and health funds find the notion of allocating health resources on the basis of evidence attractive.²⁶ Eddy has suggested that healthcare funds should be required to cover interventions only if there is sufficient evidence that they can be expected to produce their intended effects.²⁷ The Australian health minister, Dr Michael Wooldridge, who is a strong supporter of evidence based medicine, has adopted a similar position, stating "[we will] pay only for those operations, drugs and treatments that according to available evidence are proved to work."²⁶

Individual versus population health
Evidence based medicine, as described above, concentrates upon the efficacy of individual treatments. Physicians must not only address the needs of individual patients, but should also be concerned with issues of efficiency and population health.²⁸ Proponents of evidence based medicine argue that these issues can be resolved by the use of "evidence based purchasing." However, decisions reached rationally at the population level will at times conflict with those made in the interests of the individual. Evidence based medicine does not provide a means to settle such conflicts. Even attempts to replace evidence based medicine with other quantitative methods such as "decision-analysis based medical decision-making" seem unlikely to remove from medicine the need for reasoning that is based on value.²⁹

Simplistic solutions
According to Williams, "there is great pressure for research into techniques to make larger ranges of social value commensurable. Some of the effort should rather be devoted to learningor learning againhow to think intelligently about conflicts of values which are incommensurable."⁹ This is particularly the case where it comes to making decisions about allocation of health resources. Those charged with making these decisions are seeking simplistic solutions to inherently complex problemsthe danger is that through evidence based medicine we will supply them.

	Acknowledgments

Funding: No additional funding.

Conflict of interest: None.    

	References

Top References

1. Sackett DL, Rosenberg WMC, Gray JAM, Harnes RB, Richardson WS. Evidence based medicine: what it is and what it isn't. BMJ 1996; 312: 71-72[Free Full Text].
2. Chalmers I, Dickersin K, Chalmers TC. Getting to grips with Archie Cochrane's agenda. BMJ 1992; 305: 786-788.
3. Rosenberg W, Donald A. Evidence based medicine: an approach to clinical problem-solving. BMJ 1995; 312: 1122-1126.
4. Henry D. Economic analysis as an aid to subsidisation decisions. The development of Australian guidelines for pharmaceuticals. PharmacoEconomics 1992; 1: 54-67.[Medline]
5. Bastian H. The power of sharing knowledge. Consumer participation in the Cochrane Collaboration. Oxford: UK Cochrane Centre , 1994.
6. Hope T. Evidence-based medicine and ethics. J Med Ethics 1995; 21: 259-260[Medline].
7. Guyatt GH, Sackett DL, Cook DJ for the Evidence-Based Medicine Working Group. Users' guides to the medical literatures. JAMA 1994; 271: 59-63[Free Full Text].
8. Evidence-Based Care Resource Group. Evidence-based care. 1. Setting priorities: how important is this problem? Can Med Assoc J 1994; 150: 1249-1254[Abstract].
9. Williams B. Morality. Cambridge: Cambridge University Press , 1972.
10. Chalmers I. What do I want from health researchers when I am a patient? BMJ 1995; 310: 1315-1318[Free Full Text].
11. Oliver SR. How can health service users contribute to the NHS R and D program? BMJ 1995; 310: 1318-1320[Free Full Text].
12. Berger RL. Nazi sciencethe Dachau hypothermia experiments. N Engl J Med 1990; 322: 1435-1440[Medline].
13. Samei E, Kearfott KJ. A limited bibliography of the federal government-funded human radiation experiments. Health Physics 1995; 69: 885-891[Medline].
14. Angel M. The Nazi hypothermia experiments and unethical research today. N Engl J Med 1990; 322: 1462-1464[Medline].
15. Smith R. Informed consent: the intricacies. BMJ 1997; 314: 1059-1060[Free Full Text].
16. Gruppo Ialiano per lo Studio della Sopravvivenza nell Infarto Miocardio. GISSI-2: a factorial randomised trial of alteplase versus streptokinase and heparin versus no heparin among 12,490 patients with acute myocardial infarction. Lancet 1990; 336: 65-71[Medline].
17. Mulrow CD. Rationale for systematic reviews. BMJ 1994; 309: 597-599[Free Full Text].
18. US Preventive Services Taskforce. Guide to clinical preventive services. , 2nd ed. , Baltimore: Williams and Wilkins, 1995:862.
19. Hellman S, Hellman DS. Of mice but not men. Problems of the randomised clinical trial. N Engl J Med 1991; 324: 1585-1589[Medline].
20. Howson C, Urbach P. Scientific reasoninga Bayesian approach. , 2nd ed. Chicago: Open Court , 1993.
21. Shimm DS, Spece RG. Ethical issues and clinical trials. Drugs 1993; 46: 579-584[Medline].
22. Yusof S, Collins R, Peto R. Why do we need some large, simple randomised trials? Stat Med 1984; 3: 409-420[Medline].
23. Walsh JT, Gray D, Keating NA, Cowley AJ, Hampton JR. ACE for whom? Implications for clinical practice of post-infarct trials. Br Heart J 1995; 73: 470-474[Abstract/Free Full Text].
24. Hlakty MA, Califf RM, Harrell FE Jr, Lee KL, Mark DB, Muhlbaier LH, et al. Clinical judgement and therapeutic decision making. J Am Coll Cardiol 1990; 15: 1-14[Abstract].
25. Glasziou PP, Irwig LM. An evidence based approach to individualising treatment. BMJ 1995; 311: 1356-1359[Free Full Text].
26. Downey M. Trust me I'm a doctor. Sydney Morning Herald. 10 May 1997:1.
27. Eddy DK. Benefit language; criteria that will improve quality while reducing costs. JAMA 1996; 275: 650-657[Medline].
28. Maynard A. Evidence-based medicine: an incomplete method for informing treatment choices. Lancet 1997; 349: 126-128[Medline].
29. Dowie J. "Evidence-based", "cost-effective", and "preference-driven" medicine: decision analysis based medical decision making is the pre-requisite. J Health Serv Res Policy 1996; 1: 104-113. [Medline]

(Accepted 28 August 1997)