Users' Guides to the Medical Literature
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THE MEDICAL LITERATURE Users’ Guides to the Medical Literature XXV. Evidence-Based Medicine: Principles for Applying the Users’ Guides to Patient Care Gordon H. Guyatt, MD, MSc This series provides clinicians with strategies and tools to interpret and in- R. Brian Haynes, MD, PhD tegrate evidence from published research in their care of patients. The 2 key Roman Z. Jaeschke, MD, MSc principles for applying all the articles in this series to patient care relate to the value-laden nature of clinical decisions and to the hierarchy of evidence Deborah J. Cook, MD, MSc postulated by evidence-based medicine. Clinicians need to be able to dis- Lee Green, MD, MPH tinguish high from low quality in primary studies, systematic reviews, prac- C. David Naylor, MD, PhD tice guidelines, and other integrative research focused on management rec- ommendations. An evidence-based practitioner must also understand the Mark C. Wilson, MD, MPH patient’s circumstances or predicament; identify knowledge gaps and frame W. Scott Richardson, MD questions to fill those gaps; conduct an efficient literature search; critically for the Evidence-Based Medicine appraise the research evidence; and apply that evidence to patient care. How- Working Group ever, treatment judgments often reflect clinician or societal values concern- ing whether intervention benefits are worth the cost. Many unanswered ques- CLINICAL SCENARIO tions concerning how to elicit preferences and how to incorporate them in A senior resident, a junior attending, a clinical encounters constitute an enormously challenging frontier for evidence- senior attending, and an emeritus pro- based medicine. Time limitation remains the biggest obstacle to evidence- fessor were discussing evidence-based based practice but clinicians should seek evidence from as high in the ap- medicine (EBM) over lunch in the hos- propriate hierarchy of evidence as possible, and every clinical decision should pital cafeteria. be geared toward the particular circumstances of the patient. “EBM,” announced the resident with JAMA. 2000;284:1290-1296 www.jama.com some passion, “is a revolutionary devel- opment in medical practice.” She went “their positions are diametrically op- INTRODUCTION on to describe EBM’s fundamental in- posed. They can’t both be right.” Evidence-based medicine, the ap- novations in solving patient problems. The emeritus professor looked proach to clinical care that underlies the “A compelling exposition,” re- thoughtfully at the puzzled physician 24 Users’ Guides to the Medical Litera- marked the emeritus professor. and, with the barest hint of a smile, re- ture, which JAMA has published dur- “Wait a minute,” the junior attend- plied, “Come to think of it, you’re right ing the last 8 years,1 is about solving ing exclaimed, also with some heat, and too.” clinical problems. The Users’ Guides presented an alternative position stat- ing that EBM merely provided a set of Author Affiliations: Departments of Clinical Epide- The original list of members with affiliations ap- additional tools for traditional ap- miology and Biostatistics (Drs Guyatt, Haynes, and pears in the first article of the series ( JAMA. 1993; Cook) and Medicine (Drs Haynes and Jaeschke), 270:2093-2095). A list of new members appears in proaches to patient care. McMaster University, Hamilton, Ontario; Depart- the 10th article of the series ( JAMA. 1996;275: “You make a strong and convincing ment of Medicine and Office of the Dean, Faculty of 1435-1439). The following member of the Evidence- case,” the emeritus professor com- Medicine, University of Toronto, Ontario (Dr Nay- Based Medicine Working Group contributed to this lor); Department of Family Medicine, University of article: Anne Holbrook, MD, MSc. mented. Michigan, Ann Arbor (Dr Green); Department of Corresponding Author and Reprints: Gordon H. Guy- “Wait a minute,” the senior attend- Medicine, Wake-Forest University School of Medi- att, MD, MSc, Department of Clinical Epidemiology cine, Winston-Salem, NC (Dr Wilson); and Depart- and Biostatistics, Room 2C12, 1200 Main St W, ing exclaimed to her older colleague, ments of Ambulatory Care and Research, South McMaster University Faculty of Health Sciences, Hamil- Texas Veterans Health Care System and Medicine, ton, Ontario, Canada L8N 3Z5. See also Patient Page. University of Texas Health Sciences Center, San Users’ Guides to the Medical Literature Section Edi- Antonio (Dr Richardson). tor: Drummond Rennie, MD, Deputy Editor. 1290 JAMA, September 13, 2000—Vol 284, No. 10 (Reprinted) ©2000 American Medical Association. All rights reserved. USERS’ GUIDES TO THE MEDICAL LITERATURE provide clinicians with strategies and those gaps; to conduct an efficient lit- evidence of treatment effectiveness does tools to interpret and integrate evi- erature search; to critically appraise the not automatically imply that treat- dence from published research in their research evidence; and to apply that evi- ment be administered. The manage- patient care. As we developed the Us- dence to patient care.3 The Users’ ment decision requires a judgment ers’ Guides, our understanding of EBM Guides have dealt with the framing of about the trade-off between risks and has evolved. In this article, since we are the question in the scenarios, with benefits, and because values or prefer- addressing physicians, we use the term searching the literature,4 with apprais- ences differ, the best course of action EBM but what we report applies to all ing the literature in the “Validity” sec- will vary between patients and be- clinical care provisions and the rubric tion, and with applying the evidence in tween clinicians. “evidence-based health care” is equally the “Results” and “Applicability” sec- Picture a third patient, a healthy 30- appropriate. tions. Underlying these steps are 2 fun- year-old mother of 2 children who de- In 1992, in an article that provided damental principles. One, relating pri- velops pneumococcal pneumonia. No a background to the Users’ Guides, we marily to the assessment of validity, clinician would have any doubt about described EBM as a shift in medical posits a hierarchy of evidence to guide the wisdom of administering antibi- paradigms.2 In contrast to the tradi- clinical decision making. Another, re- otic therapy to this patient. This does tional paradigm, EBM acknowledges lating primarily to the application of evi- not mean that an underlying value judg- that intuition, unsystematic clinical ex- dence, suggests that decision makers ment has been unnecessary. Rather, our perience, and pathophysiologic ratio- must always trade off the benefits and values are sufficiently concordant, and nale are insufficient grounds for clini- risks, inconvenience, and costs associ- the benefits so overwhelm the risks that cal decision making, and stresses the ated with alternative management strat- the underlying value judgment is un- examination of evidence from clinical egies, and in doing so consider the pa- apparent. research. The philosophy underlying tient’s values.5 In the sections that In current health care practice, judg- EBM suggests that a formal set of rules follow, we will discuss these 2 prin- ments often reflect clinician or soci- must complement medical training and ciples in detail. etal values concerning whether inter- common sense for clinicians to effec- vention benefits are worth the cost. tively interpret the results of clinical re- Clinical Decision Making: Consider the decisions regarding ad- search. Finally, EBM places a lower Evidence Is Never Enough ministration of tissue-type plasmino- value on authority than the traditional Picture a patient with chronic pain due gen activator vs streptokinase to pa- paradigm of medical practice. to terminal cancer who has come to tients with acute myocardial infarction, While we continue to find the para- terms with her condition, has re- or clopidogrel vs aspirin to patients with digm shift a valid way of conceptual- solved her affairs and said her good- transient ischemic attack. In both cases, izing EBM, as the scenario suggests, the byes, and wishes only palliative therapy. evidence from large randomized con- world is often complex enough to in- The patient develops pneumococcal trolled trials (RCTs) suggests the more vite more than 1 useful way of think- pneumonia. The evidence that antibi- expensive agents are, for many pa- ing about an idea or a phenomenon. In otic therapy reduces morbidity and tients, more effective. In both cases, this article, we describe the 2 key prin- mortality due to pneumococcal pneu- many authoritative bodies recom- ciples that clinicians must grasp to be monia is strong. Almost all clinicians mend first-line treatment with the less effective practitioners of EBM. One of would agree that this strong evidence effective drug, presumably because they these relates to the value-laden nature does not dictate that this patient re- believe society’s resources would be bet- of clinical decisions; the other to the hi- ceive antibiotics. Despite the fact that ter used in other ways. Implicitly, they erarchy of evidence postulated by EBM. antibiotics might reduce symptoms and are making a value or preference judg- We will also comment on additional prolong the patient’s life, her values are ment about the trade-off between deaths skills necessary for optimal clinical such that she would prefer a rapid and and strokes prevented, and resources practice and we conclude with a dis- natural passing. spent. cussion of the challenges facing EBM Picture a second patient,