The Promises And Pitfalls Of Evidence-Based Medicine Nonadherence to practice guidelines remains the major barrier to the successful practice of evidence-based medicine. by Stefan Timmermans and Aaron Mauck ABSTRACT: Evidence-based medicine (EBM) aims to address the persistent problem of clinical practice variation with the help of various tools, including standardized practice guidelines. While advocates welcome the stronger scientific foundation of such guidelines, critics fear that they will lead to ���cookbook medicine.��� Studies show, however, that few guidelines lead to consistent changes in provider behavior. The hopes, fears, and mixed re- cord of EBM are rooted in the traditional professional perspective of the clinician as sole decisionmaker. Multifaceted implementation strategies that take the collaborative nature of medical work into consideration promise more effective changes in clinical practice. Esions vidence-based medicine (EBM) is commonly defined as ���the consci- entious, explicit, and judicious use of current best evidence in making deci- about the care of individual patients.���1 The term is loosely used and can refer to anything from conducting a statistical meta-analysis of accumulated research, to promoting randomized clinical trials, to supporting uniform reporting styles for research, to a personal orientation toward critical self-evaluation. EBM was initially defined in opposition to clinical experience, but later definitions have emphasized its complementary character and have aimed to improve clinical ex- perience with better evidence.2 One common implementation of EBM involves the use of clinical practice guidelines during medical decision making to encourage ef- fective care. The Institute of Medicine (IOM) defines clinical guidelines as ���systemat- ically developed statements to assist practitioner and patient decisions about ap- propriate health care for specific clinical circumstances.���3 An expert committee does the work of sifting through the scientific literature for clinicians and offers coherently sequenced recommendations based on the best available evidence aimed at everyday decision-making situations. Guidelines can be applied to any aspect of clinical care: how and when to order diagnostic or screening tests, when to provide certain medical services, how these should be performed, and how long 1 8 J a n u a r y / F e b r u a r y 2 0 0 5 H i s t o r y & C o n t e x t DOI 10.1377/hlthaff.24.1.18 ��2005 Project HOPE���The People-to-People Health Foundation, Inc. Stefan Timmermans (Timmermans@brandeis.edu) is an associate professor of sociology at Brandeis University, in Waltham, Massachusetts (on professional leave), and a Robert Wood Johnson Health and Society Fellow at the Harvard School of Public Health. Aaron Mauck is a doctoral candidate in the Department of the History of Science, Harvard University, in Boston.

patients should remain hospitalized following a procedure. n Variations and guidelines. The purpose of EBM and practice guidelines is to provide a stronger scientific foundation for clinical work, to achieve consistency, ef- ficiency, effectiveness, quality, and safety in medical care. Besides escalating health care costs and inequality in health care access, major variation in accepted clinical practices is considered a third major issue facing the contemporary U.S. health care field, because observers agree that at least some of the variation stems from overuse, underuse, and misuse of medical care.4 These problems became apparent through the work of epidemiologists examining local practice variation. This work maps the frequency of a variety of medical interventions by geographical area (based, for ex- ample, on Medicare outcomes data) and has confirmed great variability depending on where the patient receives care. Several epidemiologists have suggested that one solution is to evaluate the scientific basis of medical and surgical treatments and of- fer population-based recommendations for professional standards of care.5 Accord- ingly, EBM experts define a focus and audience for a clinical guideline retrieve, eval- uate, and synthesize the evidence based on statistical analysis summarize the benefits and risks and determine the appropriateness of the intervention. n International paradigm. It is difficult to exaggerate the resonance of EBM in contemporary health care. Many observers have elevated EBM to a new interna- tional health care ���paradigm.���6 Some indications of this new paradigm are the ap- pearance of new national and international research institutions concerned with EBM the centrality of EBM at the U.S. Agency for Healthcare Research and Quality (AHRQ) new journals and recurring editorials discussing the importance of EBM innovations in methodologies and criteria for gathering and evaluating data the surge of randomized controlled trials (RCTs) in medical research and the rise of ���causal pathways,��� ���care plans,��� and ���outcomes research��� to streamline and evaluate every aspect of health care. In addition, EBM-based curricula have changed medical education, while EBM journal clubs have sprung up in hospitals. Evidence-based thinking has also been tied to nursing and allied health professions, nutrition, public health, justice, policy, and even hospital chaplaincy. So many parties have jumped on the EBM bandwagon and so many clinical practice guidelines are churned out by individuals, professional organizations, in- surers, and others that the benefits of uniformity may disappear in the cacophony of overlapping, conflicting, and poorly constructed guidelines. With more than 1,000 guidelines created annually, calls for ���guidelines for clinical guidelines��� have been issued.7 The quality of EBM guidelines has also been questioned. In ideal cir- cumstances all decision points of a clinical practice guideline should be based on solid scientific evidence, preferably derived from a meta-review of large, dou- ble-blind RCTs. Because this ���gold standard��� of evidence is rarely available, except in industry-sponsored drug trials, researchers have come to rely on other methods for determining ���best evidence,��� such as small clinical trials with insufficient sta- tistical power, studies with a nonrandomized control group, other nonrandom- P r o m i s e s & P i t f a l l s H E A LT H A F F A I R S ~ Vo l u m e 2 4 , N u m b e r 1 1 9