Physicians' misunderstanding of normal findings.

Gorry, Pauker, and Schwartz [1] demonstrated that a normal test result, when assessed quantitatively, can sometimes be extremely valuable in differential diagnosis. In the present study we extend the principle of the normal finding to include signs and symptoms. This extension proved to be clinically valuable for the present population of patients with acute cough, because the identified normal findings provided significant (p less than 0.001) information predictive of radiographic pneumonia and unrelated to that provided by the abnormal findings. This suggests that both types of findings should be used to diagnose pneumonia efficiently. Another result of the extension of this principle to signs and symptoms was the identification of the clinicians' use (p less than 0.001) of abnormal findings but not (p greater than 0.75) normal findings when managing patients with acute cough. Several possible causes for this misuse of normal findings are discussed, including limitations in the clinicians' cognitive processing of "absent problems," emphasis on abnormal findings by patients, and confusing epidemiological terminology that discourages the recognition of pertinent normal findings.