Essential Evidence-based Medicine, Second Edition (Essential ...

What is evidence-based medicine? 13
a disease-oriented outcome. Another example is the prostate-specific antigen
(PSA) test for detecting prostate cancer. There is no question that the test can
detect prostate cancer most of the time at a stage that is earlier than would be
detected by a physician examination, so it is a positive DOE. However, it has yet
to be shown that early detection using the PSA results in a longer life span or an
improved quality of life; thus, it is not a positive POEM.
Other compiled sources of evidence are the American Society of Internal
Medicine and the American College of Physicians’ ACP Journal Club, published
by the journal Annals of Internal Medicine, and the Cochrane Library, sponsored
by the National Health Service in the United Kingdom. Both are available by subscription.
The next step for the future use of EBM in the medical decision-making
process is making the evidence easily available at the patient’s bedside. This has
been tried using an “evidence cart” containing a computer loaded with evidencebased
resources during rounds. 3 Currently, personal digital assistants (PDAs) and
other handheld devices with evidence-based databases downloaded onto them
are being used at the bedside to fulfil this mission.
How to put EBM into use
For many physicians, the most complex part of the process of EBM is the critical
appraisal of the medical literature. Part of the perceived complexity with this
process is a fear of statistics and consequent lack of understanding of statistical
processes. The book will teach this in several steps. Each step will be reinforced
on the CD-ROM with a series of practice problems and self-assessment
learning exercises (SALEs) in which examples from the medical literature will
be presented. This will also help you develop your skills of formulating clinical
questions, and in time, you will become a competent evaluator of the medical
literature. This skill will serve you well for the rest of your career.
The clinical question: background vs. foreground
You can classify clinical questions into two basic types. Background questions
are those which have been answered in the past and are now part of the “fiber of
medicine.” Answers to these questions are usually found in medical textbooks.
The learner must beware, since the answers to these questions may be inaccurate
and not based upon any credible evidence. Typical background questions relate
to the nature of a disease or the usual cause, diagnosis, or treatment of illnesses.
3 D. L. Sackett & S. E. Straus. Finding and applying evidence during clinical rounds: the “evidence cart”.
JAMA 1998; 280: 1336–1338.