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When I was attending school in wartime Britain, staples of the curriculum, along with cold baths, mathematics, boiled cabbage, and long cross-country runs, were Latin and French. It was obvious that Latin was a theoretical exercise—the Romans were dead, after all. However, although France was clearly visible just across the Channel, for years it was either occupied or inaccessible, so learning the French language seemed just as impractical and theoretical an exercise. It was unthinkable to me and my teachers that I would ever put it to practical use—that French was a language to be spoken.

This is the relationship too many practitioners have with the medical literature—clearly visible but utterly inaccessible. We recognize that practice should be based on discoveries announced in the medical journals. But we also recognize that every few years the literature doubles in size, and every year we seem to have less time to weigh it,1 so every day the task of taming the literature becomes more hopeless. The translation of those hundreds of thousands of articles into everyday practice appears to be an obscure task left to others, and as the literature becomes more inaccessible, so does the idea that the literature has any utility for a particular patient become more fanciful.

This book, now in its third edition, is intended to change all that. It is designed to make the clinician fluent in the language of the medical literature in all its forms. To free the clinician from practicing medicine by rote, by guesswork, and by their variably integrated experience. To put a stop to clinicians being ambushed by drug company representatives, or by their patients, telling them of new therapies the clinicians are unable to evaluate. To end their dependence on out-of-date authority. To enable the practitioner to work from the patient and use the literature as a tool to solve the patient's problems. To provide the clinician access to what is relevant and the ability to assess its validity and whether it applies to a specific patient. In other words, to put the clinician in charge of the single most powerful resource in medicine.

The Users' Guides Series in JAMA

I have left it to Gordon Guyatt, MD, MSc, the moving force, principal editor, and most prolific coauthor of the Users' Guides to the Medical Literature series in JAMA, to describe the history of this series and of this book in the accompanying preface. But where did JAMA come into this story?

In the late 1980s, at the invitation of my friend David Sackett, MD, I visited his department at McMaster University to discuss a venture with JAMA—a series that examined the evidence behind the clinical history and examination. After these discussions, a series of articles and systematic reviews was developed and, with the enthusiastic support of then JAMA Editor in Chief George Lundberg, MD, JAMA began publishing the Rational Clinical Examination series in 1992.2 By that time, I had formed an excellent working relationship with the brilliant group at McMaster. Like their leader, Sackett, they tended to be iconoclastic, expert at working together and forming alliances with new and talented workers, and intellectually exacting. Like their leader, they delivered on their promises.

So, when I heard that they were thinking of updating the wonderful little series of Readers' Guides published in 1981 in the Canadian Medical Association Journal (CMAJ), I took advantage of this working relationship to urge them to update and expand the series for JAMA. Together with Sackett, and first with Andy Oxman, MD, and then with Gordon Guyatt taking the lead (when Oxman left to take a position in Oslo), the Users' Guides to the Medical Literature series was born. We began publishing articles in the series in JAMA in 1993.3

At the start, we thought we might have 8 or 10 articles, but the response from readers was so enthusiastic and the variety of types of article in the literature so great that ever since I have found myself receiving, sending for review, and editing new articles for the series. Just before the first edition of this book was published in 2002, Gordon Guyatt and I closed this series at 25, appearing as 33 separate journal articles.

The passage of years during the preparation of the original JAMA series and the publication of the first edition of this book had a particularly useful result. Some subjects that were scarcely discussed in the major medical journals in the early 1990s but that had burgeoned years later could receive the attention that had become their due. For instance, in 2000, JAMA published 2 Users' Guides4,5 on how readers should approach reports of qualitative research in health care. To take another example, systematic reviews and meta-analyses, given a huge boost by the activities of the Cochrane Collaboration, had become prominent features of the literature, and as Gordon Guyatt points out in his preface, the change in emphasis in the Users' Guides to preappraised resources continues.

The Book

From the start, readers kept urging us to put the series together as a book. That had been our intention right from the start, but each new article delayed its implementation. How fortunate! When the original Readers' Guides appeared in the CMAJ in 1981, Gordon Guyatt's phrase “evidence-based medicine” had never been coined, and only a tiny proportion of health care workers possessed computers. The Internet did not exist and electronic publication was only a dream. In 1992, the Web—for practical purposes—had scarcely been invented, the dot-com bubble had not appeared, let alone burst, and the health care professions were only beginning to become computer literate. But at the end of the 1990s, when Guyatt and I approached my colleagues at JAMA with the idea of publishing not merely the standard printed book but also Web-based and CD-ROM formats of the book, they were immediately receptive. Putting the latter part into practice has been the notable achievement of Rob Hayward, MD, of the Centre for Health Evidence of the University of Alberta.

The science and art of evidence-based medicine, which this book does so much to reinforce, has developed remarkably during the past 25 years, and this is reflected in every page of this book. Encouraged by the immediate success of the first and second editions of the Users' Guides to the Medical Literature, Gordon Guyatt and the Evidence-Based Medicine Working Group have once again brought each chapter up to date for this third edition. They have also added 6 completely new chapters: Evidence-Based Medicine and the Theory of Knowledge, How to Use a Noninferiority Trial, How to Use an Article About Quality Improvement, How to Use an Article About Genetic Association, Understanding and Applying the Results of a Systematic Review and Meta-analysis, and Network Meta-analysis.

An updated Web version of the Users' Guides to the Medical Literature will accompany the new edition. As part of the online educational resource, JAMAevidence, the Users' Guides to the Medical Literature online is intertwined with the online edition of The Rational Clinical Examination: Evidence-Based Clinical Diagnosis. Together they serve as the cornerstones of a comprehensive online educational resource for teaching and learning evidence-based medicine. Interactive calculators and worksheets provide practical complements to the content, and downloadable PowerPoint presentations serve as invaluable resources for instructors. Finally, podcast presentations bring the foremost minds behind evidence-based medicine to medical students, residents, and faculty around the world.

Once again, I thank Gordon Guyatt for being an inspired author, a master organizer, and a wonderful teacher, colleague, and friend. I know personally and greatly admire a good number of his colleagues in the Evidence-Based Medicine Working Group, but it would be invidious to name them, given the huge collective effort this has entailed. This is an enterprise that came about only because of the strenuous efforts of many individuals. On the JAMA side, I must thank Annette Flanagin, RN, MA, a wonderfully efficient, creative, and diplomatic colleague at JAMA. All of this was coordinated and kept up to schedule by the energy and meticulous efficiency of Kate Pezalla, MA. My colleague, Edward Livingston, MD, a surgeon and a perceptive critic, is taking over the Users' Guides to the Medical Literature series at JAMA, and I am confident it will prosper in his hands. In addition, I acknowledge the efforts of our partners at McGraw-Hill Education—James Shanahan, Scott Grillo, Michael Crumsho, and Robert Pancotti.

Finally, I thank my friends Cathy DeAngelis, MD, MPH, and her successor, Howard Bauchner, MD, MPH, former and current Editors in Chief of The JAMA Network, for their strong backing of me, my colleagues, and this project. Howard inherited this project. Once I found out that his immediate and enthusiastic acceptance of it was based on his regular use of early articles in the Users' Guides series, any concern about its reception vanished. Indeed, Howard was the instigator of Evidence-Based Medicine—An Oral History,2,3 a video series of personal views on the birth and early growth of evidence-based medicine that has helped put the Users' Guides into perspective. Howard's infectious good spirits and sharp intelligence bode well for further editions of this book.

Drummond Rennie, MD
University of California, San Francisco


1. +
Durack  DT. The weight of medical knowledge. N Engl J Med. 1978;298(14):773-–775.  [PubMed: 342963]
2. +
Smith  R, Rennie  D. Evidence-based medicine—an oral history. JAMA[JAMA and JAMA Network Journals Full Text]. 2014;311(4):365-–367.  [PubMed: 24449049]
3. +
Evidence-based medicine—an oral history website. Accessed August 17 , 2014.

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