Metadiagnosis. An epistemologic model of clinical judgment.

For convenience, clinical findings are often artificially forced into finite pigeonholes such as "positive" or "negative." This convention obscures much of the inherent uncertainty in diagnosis and can result in serious misinterpretation of the significance of certain observations. Unhappy past experience with the poor predictive accuracy of electrocardiographic stress testing in asymptomatic patients is one such example. As an aid to understanding the limitations of clinical diagnosis, an epistemologic model of judgment was developed. According to this model, judgments are viewed as existing on three separate dimensional levels, each of which is rigorously defined and unambiguously quantified. The first dimension expresses diagnostic belief in terms of a numeric probability; the second quantifies the degree of confidence in the probability estimate; and the third defines the information that derives from the probability and confidence. The practical clinical relevance of this conceptual model is illustrated by applying it to a common clinical problem: the interpretation of a "positive" electrocardiographic stress test result in an asymptomatic man. This process--termed herein "metadiagnosis"--provides a new perspective by which the art of diagnosis might be made more accurate and explicit.