Bradley F. Marple, MD is Professor and Vice-Chair of the Department of Otolaryngology at University of Texas Southwestern Medical Center in Dallas, and is a member of ENT Today’s editorial board.
Explore This IssueOctober 2008
It has been suggested that since its introduction in 1992,1 the term evidence-based medicine (EBM) has reached almost iconic status within the medical lexicon.2 Ironically, when that suggestion is subjected to the rigors of EBM, it risks being cast upon the scrap heap of grade D evidence by virtue of its apparent vapid evidence!
Fortunately, there are some data beyond that of mere expert opinion to support the impact EBM has made within the field of health care. A simple Pubmed literature search in August using the term evidence-based yielded more than 43,000 citations. So even if the iconic status of EBM cannot be fully supported, it appears that EBM has made a rapid and significant impact on the way in which medical information is processed. Such rapid changes within a world that has long been based in tradition, experience, and dogma3 appear to represent what might be better described as a culture shift. But, as with all such cultural shifts, changes are often met with disagreement and resistance. The challenge to the profession during times of change is to support healthy discussion without losing sight of important issues. Change is healthy, but it is also frequently uncomfortable.
At its core, EBM provides for a systematic approach to use of the best available scientific information, allowing for more objectivity in diagnosing and treating individual patients. In fact, the concept of EBM was best described by David Sackett as the conscientious, explicit, and judicious use of the current best evidence in making decisions about individual patients.4 It involves using a set of skills to acquire and evaluate the available medical literature so that the most accurate information can be used as the basis of clinical decision making, thus minimizing the impact of incorrect, inadequate, biased, or outdated information.
The concept of EBM is quite appealing in its logic and simplicity. In essence, most would agree that health care decisions based in the best scientific evidence would be ideal. In fact, the New York Times Magazine Year in Review heralded EBM as one of the most influential concepts of 2001.5 However, areas of disagreement have arisen between proponents of EBM and its detractors.6,7 Those favoring EBM feel strongly that it provides the tools necessary to repair problems traditionally encountered in health care. Wide variations in clinical practice, use of unproven therapeutic interventions, and over-reliance on anecdotal experience are among some of the problems cited for which application of EBM may offer some help. Opponents, on the other hand, point out the practical and philosophical flaws inherent in the principles of EBM, arguing that EBM inadequately accounts for the complexity of medical practice and devalues the role of the individual clinician in patient care decision making. Examination of such criticisms may provide for some clarity regarding the current impact of EBM on the delivery of health care and may serve to refocus the expectations for its future.
For purposes of this discussion, the major criticisms that have been raised are presented here as five main themes.
Perhaps the most fundamental of these criticisms addresses a veiled empiricism that may philosophically underpin the concept of EBM. A basic tenet of EBM is its elevation of experimental evidence over pathophysiological or other forms of knowledge. In order to achieve this, it is assumed that the scientific observations on which experimental evidence is based can be made independent of the theories and biases of the observer. However, the impossibility of bias-free observation has been recognized for centuries. In the late 19th century, French mathematician and physicist Pierre Duhem argued that science enables a large number of empiric facts to be related to one another through use of a relatively small number of principles, but the observations themselves cannot be carried out by a naive observer.8 In other words, all observations are influenced by the perceptions and beliefs of the observer, and therefore bias can never be eliminated. Using this reasoning, critics suggest that EBM may, in fact, unknowingly create an environment of over-reliance in the power of empiricism to determine what constitutes reliable knowledge.
Definition of Research Quality
The next critical theme addresses the way in which research is defined and graded. Within EBM, the definition of evidence is relatively narrow and tends to devalue some forms of information that may be of importance within the health care arena.9 Research methodology is used as a basis for EBM grades. Those research methodologies thought to be less vulnerable to bias are graded as higher, and those thought to be more vulnerable are graded as lower.10 However, to date there is no evidence to suggest that higher EBM grades of evidence are any more reliable than lower grades. In 2000, Benson and Hartz compared observational reports addressing 19 diverse treatments with randomized, controlled trials for the same treatments. They found little evidence that estimates of treatment effects in observational studies reported after 1984 are either consistently larger than or qualitatively different from those obtained in randomized, controlled trials.11 Further, the meta-analyses and randomized controlled trials that constitute the highest grade of research may not address many of the issues relevant to the complexities of patient care by failing to integrate other nonstatistical forms of medical information, such as patient-specific issues and professional experience.12
Is EBM Evidence-Based?
The third theme offered by critics is perhaps the most ironic. EBM itself is not evidence-based, as it fails to meet its own empiric tests of efficacy. EBM is based on the notion that clinicians armed with the best available information will bring about an improvement in the quality of medical care. Despite the paucity of data to support the impact of EBM, many of its proponents remain firmly committed to this belief. Goodman, for example, suggested that to practice medicine in a manner inconsistent with EBM is unethical.13 To date, however, there remains no convincing direct evidence that demonstrates that care provided by practitioners whose practice is based on data isolated to applied health care research differ meaningfully from care given by those who rely on basic knowledge and their own clinical experience. Realistically, it is impossible to completely separate these two groups, as the complexity of patient care requires physicians to make use of many forms of information. So it seems that EBM suffers the same fate as so many issues in medicine that evade simple assessment by a randomized, controlled trial, and by virtue of that will likely not be supported by high-grade evidence.9
Impact on the Individual Patient
There may be some limitations of the effect of EBM on the individual patient due to both patient- and disease-related variables. Individual patient circumstances, stresses, and values will inevitably vary. And although disease-specific data will be available for the most common disease entities, gaps in reasonable data will continue to exist for varied subpopulations of patients, uncommon diseases, and disease variants.14 The clinical judgment provided by experienced practitioners will always be called on to resolve the complexities that exist in the setting of patient care.
Finally, loss of autonomy as it relates to the doctor-patient relationship by reducing the patients’ right to select treatments best suited for their individual circumstances is criticized by some as a potential flaw in EBM. This argument relates directly and indirectly to patient access to health care. EBM could be manipulated for use as a cost-cutting tool by preventing access to procedures or medications that are not proven to the standards of Grade A or B evidence. Further, EBM could increase the cost of health care by creating standards that require higher levels of proof before interventions would be available to the patient. To date, the true impact of EBM on cost and access to health care remains unknown.6,7
At its inception in 1992, EBM may have been seen as a challenge to, if not replacement for, traditional medicine. Evidence that was adherent to a narrow set of definitional standards was pitted against clinical judgment and physician experience, creating what appeared initially to be an adversarial interaction. Critiques, both practical and philosophical, have served to diminish the absolute differences between EBM and traditional medicine in lieu of a more balanced view of the role evidence-based medicine can play as a tool in the practice of medicine. Interestingly, none of the critics cited in this editorial suggest that high-quality evidence should be ignored in the overall context of clinical care. Instead, each argues that EBM should serve as one of many useful tools to help physicians address the varied and complex challenges of patient care.
In point of fact, EBM has responded and evolved substantially since that time, as it has become more practical in its integration with traditional medicine. The emphasis now focuses on integrated decision making by the clinician. Perhaps this is best stated by one of the pioneers of EBM, Brian Haynes, MD, PhD:
As we continue our journey through the era of research-informed health care, the benefits that our patients will receive will depend increasingly on making care decisions that incorporate the clinical state and circumstances of each patient, their preferences and actions, and the best current evidence from research that pertains to the patient’s problem. The nature and scope of clinical expertise must expand to balance and integrate these factors.15
So, rather than a culture shift, it appears that the emergence of EBM marks an evolutionary step in the methodological approach to information processing. Increasingly available high-grade evidence provides sound information that can play a role in clinical decision making, but is not intended to replace physician experience and other forms of information. Indeed, in the era of research-enhanced health care, it remains prudent to still consider all information that is available.
- Evidence-Based Medicine Working Group. Evidence-based medicine: a new approach to teaching the practice of medicine. JAMA 1992;268:2420-5.
- Paris J. Evidence-based psychiatry: what it is and what it isn’t. CPA Bulletin 2002;34:32-4.
- Jenkins TR. It’s time to challenge surgical dogma with evidence-based data. Am J Obstet Gynecol 2003;189;423-7.
- Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence-based medicine: what it is and what it isn’t. BMJ 1996;312:71-2.
- Hitt J. Evidence-Based Medicine. New York Times Magazine, Dec. 9, 2001.
- Cohen AM, Hersch WR. Criticisms of evidence-based medicine. Evid Based Cardiovas Med 2004;8:197-8.
- Buetow S, Upshur R, Miles A, Loughlin M. Taking stock of evidence-based medicine: opportunities for its continuing evolution. J Eval Clin Prac 2006;12:399-404.
- Harari, E. Whose evidence? Lessons from the philosophy of science and the epistemology of medicine. Aust NZ J Psychiatry 2001;35:724-30.
- Haynes RB. What kind of evidence is it that evidence-based medicine advocates want health care providers and consumers to pay attention to? BMC Health Serv Res 2002;2:3.
- Sackett DL, Straus SE, Richardson WS, Rosenberg W, Haynes RB. Evidence-Based Medicine: How to Practice and Teach EBM. Edinburgh: Churchill Livingstone, 2000.
- Benson K, Hartz AJ. A comparison of observational studies and randomized, controlled trials. N Engl J Med 2000; 342:1878-86.
- Upshur RE, VanDenKerkhof EG, Goel V. Meaning and measurement: an inclusive model of evidence in health care. J Eval Clin Prac 2001;7:91-6.
- Goodman KW. Ethics and Evidence-Based Medicine: Fallibility and Responsibility in Clinical Science. Cambridge: Cambridge University Press, 2003.
- Jones GW, Sagar SM. Evidence-based medicine. No guidance is provided for situations for which evidence is lacking. BMJ 1995;311:258.
- Haynes RB, Devereaux PJ, Guyatt GH. Clinical expertise in the era of evidence-based medicine and patient choice. Evidence-Based Medicine 2002;83:383-6.
©2008 The Triological Society