Evidence-Based Medicine

Best Practice or Restrictive Dogma

Desmond J Sheridan

• Publisher: ICP
• Year: 2016
• ISBN:
  9781783267644
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

The concept of evidence-based medicine was launched in 1991 as a new paradigm to inform medical practice and has risen to be regarded as the gold standard. It rapidly gained the attention of medics, health service managers and the general media as it presented a means to improve efficiency and effectiveness of service delivery. Despite its stunning success in capturing the health agenda, the campaign that launched evidence-based medicine has also attracted criticism, particularly from clinicians and philosophers concerned about its selective views of knowledge and evidence, and for its denigration of reasoning, clinical experience and judgement.Evidence-Based Medicine traces this movement from its launch to its meteoric rise, examining what it has done for healthcare and medicine in the context of changes in science policy and the long-running criticism held against the movement for its inherent weaknesses.As evidence-based medicine will remain an important feature of healthcare in the decades to come, this book is perfect for healthcare professionals, medical scientists, health service managers and public health experts looking for a critical examination of the topic.

Chapter 1

The Origins of Evidence-Based Medicine

The rise of Evidence-Based Medicine, often referred to as EBM, during the last years of the 20^th century and early in the 21^st has been both rapid and dramatic. Apart from a small number of committed advocates it was unheard of prior to the 1990s but since then it has come to occupy a powerful role in medicine with official backing and sponsorship from governments and strong support within the medical profession itself, as well as many allied professions and lay groups. Along the way EBM has also attracted significant dissent, mainly among philosophers concerned with the concepts and principles behind it, but it has not been short of vociferous defenders and this has led to a lively exchange between detractors and advocates. This discussion has largely been confined to academia, apart from the occasional spill over into the general media. It is without doubt one of the most important developments in medicine during the past half century. What is it and from where did it come?

EBM: Brand New or New Branding?

The term Evidence-Based Medicine was first used in 1991¹ and more formally in 1992.² At first reading it appears a fairly innocuous phrase, even a statement of the obvious. What could be controversial about medicine based on evidence? What kind of medicine would be evidence-based? The apparent simplicity of the phrase belied hidden complexities and the far reaching ambitions which its proponents had in mind, which were nothing short of a new approach to the teaching and practicing of medicine. What did it mean? A definition offered in a defence of EBM³ was as follows, “Evidence-based medicine is the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients.” Again, on first reading there appears to be nothing contentious in this, but then there are the thorny questions of what constitutes evidence, what does it include or exclude and what does it prioritise and relegate. Neither does this definition specify what is meant by “best evidence” nor how and by what means it would be identified. These questions have been at the root of much of the dissent surrounding EBM in the years that followed. But first I will consider EBM in the context of developments in medicine over time. Is EBM new or a rebranding of something which had existed previously?

The title EBM was new in that it had not been in use previously and it gave a new name to the field it represented. It also gave a new impetus for a modernisation that was needed to facilitate and manage the explosion of medical information that had begun in the 1970s. By the late 1970s, it was already becoming clear that new methods were needed to manage the increased volume of scientific information being produced. To illustrate this, Durrack⁴ weighed volumes of the Index Medicus, an annual comprehensive list of articles published in medical science journals since 1874. These had been stable for many decades, but doubled in weight between 1946 and 1955 and then increased over seven fold between 1955 and 1977. EBM advocated new ways to teach and practice medicine in a manner that would incorporate this new knowledge. The methods of EBM have been widely published and adopted, although not without controversy. Supporters of EBM have reminded us that it was voted “idea of the year” by the New York Times in 2001⁵ and considered among a list of medical milestones in a survey carried out by the British Medical Journal.⁶ The EBM movement, as it came to be known, can therefore reasonably claim to have articulated the need for a new development in medical teaching and practice to reflect the rapid expansion of clinical research and the need to manage and interpret the increased amount of scientific information being published.

However, the idea that the EBM movement had invented a new method of practicing medicine seems less credible when one looks at its development in the context of what preceded it. The need for more efficient management of scientific medical information had already been identified and would become inevitable, given the extraordinary advances which were taking place in computing and communication technology. Credit is due to the EBM movement for its skilled use of rhetoric to capture the agenda and to galvanise the medical community into action sooner than might otherwise have occurred. However, in doing so, there are aspects of the case it made, particularly in relation to its novelty and the methods used which I will argue, were not always justified. Advocates of EBM, in response to critics, have acknowledged that “depending on one’s perspective” the origins of EBM extend back centuries.⁷ What then is the history of collecting evidence for the purpose of improving medical practice? It is worth looking at this in some detail because some of the adverse reactions to EBM have in my view had as much to do with the manner in which it was presented as the content of the message it embodies. This matters if we are to identify what is valuable in the concept and avoid throwing the baby out with the bathwater.

EBM: The McMaster Model

The story of EBM in our own time took off in 1991 with a paper published from McMaster University,¹ which has often been referred to by subsequent writers as having coined the phrase EBM. This and a subsequent paper,² published the following year by authors calling themselves The EBM Group, again mainly based at McMaster, has been highly influential in advocating EBM and I will discuss these two papers in some detail. The 1991 article consisted of a one page editorial which described a case history of possible iron deficiency anaemia investigated by a young internist. The writer invites readers to envisage two scenarios labelled “The way of the past” and “The way of the future”. In the former, the internist relies on what she was told by senior colleagues during earlier training and proceeds accordingly. In the latter, she refers immediately to the literature to obtain information about relevant tests in making the diagnosis. In the process she discovers that what she was told during training conflicts with the literature and that her laboratory’s normal range for the test is misleading. She estimates a pre-test probability of iron deficiency anaemia (based on published information about the prevalence of the illness in a group of patients with similar clinical features) and orders the test. She then calculates the post-test probability of iron deficiency anaemia based on published information about the sensitivity (how good it is in identifying cases) and specificity (how good it is at identifying only real cases and avoiding misdiagnosing people with or without the illness) of the test, and manages the case accordingly.

The article then used the scenarios to describe “the way of the past” as one in which clinicians looked solely to what it referred to as “authority” for information and guidance regarding patient management. In contrast “the way of the future”, called EBM, would involve clinicians quickly searching the literature to obtain relevant information to guide clinical management. In order to practice EBM, clinicians would need to learn skills in literature retrieval and evaluation as well as the applicability of information obtained to their patients. The page on which the article appeared even included an advert for the journal as being primarily intended to further EBM.

The essence of the case therefore was that evidence based on the experience and the opinion of colleagues including those in senior positions may be unreliable. Information derived directly from the literature is superior for patient management and clinicians need to learn the skills to do so. This seems fairly obvious today, but given the rapid expansion of clinical research during the preceding decades it was undoubtedly worth emphasising at the time. It is not difficult to see where the seeds of dissent would come from when one looks at the way the article relied so heavily on rhetorical methods to sell what is in effect an important and valuable message. The author’s choice of rhetoric, skilfully constructed but rather crudely directed in order to make the case for EBM was bound to attract dissent.

A more formal announcement of EBM was made in a follow-up article in 1992² written by what had then become The EBM Working Group. This consisted of 32 members, of whom 24 were affiliated to McMaster University including the author of the 1991 editorial who was its chairman. The predominant specialism among the group was clinical epidemiology. The paper began by announcing that a new paradigm for medical practice was emerging which de-emphasised what it described as intuition, unsystematic clinical experience and pathophysiology as sufficient rationale for clinical decision making, stressing instead the examination of evidence from clinical research. It then repeated the fictional clinical scenarios used in the 1991 paper to illustrate “the way of the past” and “the way of the future” and invited readers to compare seeking advice from a senior colleague with the use of the literature to make an informed decision. Once again, the unfortunate senior colleagues consulted, were in conflict with the evidence obtained from the literature and the young internist was able avoid being misled by going independently to primary sources of information in the literature.

It is not difficult to envisage why this rhetorical approach might have irritated some clinicians who would fall into the “senior colleague” category. Some might not unreasonably have felt that they were being consigned to the dustbin of history. Later in the paper the EBM group did acknowledge a role for clinical skills, an understanding of pathophysiology, compassion and sensitivity to the emotional needs of patients. However, the fundamental concept advocated by the group was the idea of a hierarchy of evidence in medicine, with randomised controlled trials at the top and all other forms of evidence being of lesser quality and reliability. The teaching of traditional clinical skills was to be provided by clinicians, but under the guidance of experts trained in EBM as minders to ensure the “way of the future” was correctly taught. In this way students would learn how to “precisely define a patient problem” and “what information is required to resolve it”. This was to be called “critical appraisal” and was something the group considered had not been part of traditional teaching methods.

The paper then described the medical curriculum at McMaster University Department of Medicine which the authors judged to be the strongest in teaching EBM although no evidence or other information was presented as to how this was arrived at. The main features of this program are outlined in Box 1.1. The inclusion of specific time to teach students how to access and evaluate published literature may not have been widely included in curricula at the time and its emphasis would have been helpful. Stressing the need for communication technology to provide access to the literature once again was helpful. However, the notion that an intransigent medical establishment was resisting this is hardly justified when one looks at the speed with which communication technology has been widely adopted in medicine, which seems hardly less swift than in other areas of education. In practice, this was evolving widely at the time, but not in the way advocated. To be effective, these systems needed to be available to groups of students and in practice they were implemented most widely in hospital library facilities. I suspect that for most practicing clinicians the idea of interrupting, for example, the clinical assessment of a patient while teaching or during rounds in order to undertake immediate literature searches would not be considered helpful. Furthermore, while some patients might understand its purpose, others might feel it diminished their experience of the consultation and their emotional needs. It also underestimates the ability of students to capture the questions and uncertainties that arise on the ward and to investigate them later. In any event, technology has moved on and most students these days have personal portable devices which can provide all of this technology.

Box 1.1 The EBM Program at McMaster.²

1.A weekly afternoon devoted to teaching reliable methods for interpreting published articles related to diagnosis and treatment and discussion of clinical cases and relevant literature.

2.Facilities for literature searching made available on teaching wards to access relevant information immediately.

3.Candidates who had received training in clinical epidemiology were appointed to the Dept. of Medicine, because it was argued, such individuals “have the skills and commitment to practice EBM”. The residency program also worked to ensure that teaching roles were made available to them.

4.Rigorous evaluation of attending physicians’ effectiveness in teaching EBM was instituted.

5.Attending physicians were encouraged to form partnerships to attend each other’s rounds and provide observations and feedback.

6.Attending physicians were required to be “enthusiastic and effective” role models for the practice of EBM.

7.Training in clinical skills provided by clinicians with guidance from experts in EBM.

Clinical epidemiology is undoubtedly an essential specialism in medicine, however, the EBM group did not set out any evidence to support its belief that this expertise uniquely provides the “skills and commitment” to practice EBM as distinct from any other. The group itself was composed mostly of epidemiologists, which poses a risk of bias in favour of an exclusive and self-promoting logic. If I am a clinical epidemiologist, and I believe that EBM is the future of medicine, and that only clinical epidemiologists holding similar beliefs to mine can teach EBM, then only my views can succeed and all other avenues are excluded. This would seem contrary to a meaningful and one might add evidence based debate within the faculty and to restrict avenues for development.

Evaluation and appraisal of physicians have developed marke...

Table of contents

• Cover
• Halftitle
• Title
• Copyright
• Dedication
• Preface
• Contents
• Chapter 1 The Origins of Evidence-Based Medicine
• Chapter 2 Evidence-Based Medicine in the UK
• Chapter 3 The Cochrane Collaboration
• Chapter 4 Evidence-Based Medicine and the Evolution of Health Related Research
• Chapter 5 Hypothesis, Evidence, Knowledge and Reasoning in Medicine: Certainty and Uncertainty
• Chapter 6 Evidenced-Based Medicine and Medical Science
• Chapter 7 Impact of Evidence-Based Medicine on Clinical Practice: Achievements and Limitations
• Chapter 8 Evidence-Based Medicine and Medical Professionalism
• Chapter 9 The Future of Evidence-Based Medicine
• Index