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Logo of bmjThis ArticleThe BMJ
BMJ. 2007 October 13; 335(7623): 777.
PMCID: PMC2018791
Medical Classics

Clinical Epidemiology: A Basic Science for Clinical Medicine

Allen F Shaughnessy, associate program director, Tufts University family medicine residency at Cambridge Health Alliance, Malden, MA, USA

While many were learning to “study a study and test a test” in the early 1980s, another approach was developing in a small blue collar town in Ontario, Canada, at a new medical school. Internists calling themselves clinical epidemiologists (and refusing to define clinical epidemiology) were putting together a series of articles for the Canadian Medical Association Journal called “Clinical Epidemiology Rounds.”

The article series was “prepared for those clinicians who are behind in their reading.” The huge success of this series led to the expansion of the concepts in the book Clinical Epidemiology: A Basic Science for Clinical Medicine.

The book emphasises formal probabilistic reasoning as a vital aspect of medical practice. This approach would later turn medicine on its head in what would become the underpinning of “evidence based medicine.” The term is nowhere in the book; it would not be coined until 1991.

The diagnosis section takes diagnostic reasoning out of the realm of intuition and magic and breaks the process down by explaining the analytic process and pointing out how errors occur. The section on management urges clinicians to rely on research rather than individual experiences to estimate prognosis and to decide on the best therapy. The authors introduced the number needed to treat statistic, emphasised the crucial role of randomisation in study design, and promoted the use of confidence intervals rather than p values to understand the magnitude of effect.

The book was written by clinician-researchers with a strong contrarian streak, which was needed to shake up the status quo. For example, in a well argued editorial written before the book, lead author David Sackett called for “the mandatory retirement of experts” (but failed to heed his own advice many years later).

These authors at the McMaster School of Medicine planted the seeds that would grow into evidence based medicine and information mastery. Opening in 1965, McMaster was the first medical school to introduce problem based learning. It was this environment of inquiry—and perhaps the labouring of young Turks in the shadow of a more established medical school just down the road in Ontario—that resulted in this iconoclastic approach to medicine embodied in the book. The book is dedicated to H L Mencken, Kurt Vonnegut Jr, Douglas Adams, and (wink, wink) the emperor's new clothes.

Over 30 years later, evidence based medicine would be named a “medical milestone” by BMJ readers. To understand the genius of EBM, one only has to explain what it means to friends and relatives outside of medicine. A careful explanation of how decisions should be based on the best evidence rather than solely on personal clinical experience will be met with blank stares and perhaps a reaction I often hear: “You mean you have to TEACH doctors to do this?”

It is just a sign of how any discipline, once it cloisters itself away from the greater world, can go off on the wrong trail, branching away from science to a boggy marsh of intuition, opinion, and reason revered as clinical experience. The return of empiricism as embodied in evidence based medicine, and its slow ascendance over eminence based medicine, is in large part the result of this book.


Clinical Epidemiology: A Basic Science for Clinical Medicine

By David L Sackett, R Brian Haynes, Gordon H Guyatt, Peter Tugwell

First published 1985

Articles from The BMJ are provided here courtesy of BMJ Publishing Group