Original Article: A Primer on the Precision and Accuracy of the Clinical Examination
A Primer on the Precision and Accuracy of the Clinical Examination: Introduction
This background article will introduce and explain the terms and concepts that are being used in the series of overviews on the rational clinical examination that begins in this issue of The Journal. It includes definitions and explanations of certain key concepts, clinical examples, guides for reading clinical journals about a diagnostic test, and a blank “working table” that you can use to apply the concepts on your own.
Background articles in this series will discuss selected issues in the precision and accuracy of the clinical examination in greater detail or extend them to more complex diagnostic situations. Some of these issues are also discussed in clinical epidemiology textbooks.1
Of course, the precision and accuracy of the clinical examination are not the only concerns in the clinical encounter, and their proper application provides only the starting point for decisions about how certain we need to be about a diagnosis before we act on it (the decision threshold) and how we ought to incorporate the concerns of both patients and society in deciding whether and how to act. Later background articles will discuss these additional considerations; this one will be confined to precision and accuracy.
Like others in the series, this background article will be introduced with a patient.
One of your patients, whom you have not seen for several years, is admitted to the orthopedic service after a packing crate has tipped over onto his leg, producing an unstable fracture of his distal tibia and fibula. You stop by to see him as he is being prepared for surgery. He is alert and hemodynamically stable but smells of alcohol (at 10 am) and has 3 spider nevi on his upper chest (but no gynecomastia or asterixis). He is obese, and his belly is prominent. Among the questions that are raised in your mind, xsthe following are of special significance:
Is this man an alcoholic? You would place the odds for this disorder at 50-50 (and the science of the art of how clinicians generate these odds will be the subject of a later background article). The answer to this diagnostic question is important in the long run and in protecting him from the complications of acute withdrawal during and after his operation.
Does he have ascites? You are much less sure here, but if he is alcohol dependent you would place the odds that the prominence of his belly represents ascites also at 50-50. Again, it would be important to know whether he has this manifestation of advanced alcoholic liver damage.
Your options for answering these questions are several. To explore his possible alcohol ...