Southwest Gastroenterology Associates, Inc.

A medical history serves to record the patient's complaints and translate them into clear-cut, medically defined symptoms. A poorly defined symptom loses most of its discriminative power as a diagnostic test for a medical work-up. If physicians are uncertain about the exact meaning of a symptom, they have to account for the possibility of multiple competing interpretations for the identical set of complaints. Multiple possible interpretations of a single symptom diminish its value as a diagnostic test and result in test degeneracy. A modified Bayes' formula is used to quantify the influence of test degeneracy on post-test probability. The physician needs to help his patients to phrase their complaints in a fashion that limits the number of possible interpretations. A poor medical history diminishes the opportunity to establish a diagnostic suspicion with a high probability early on. The subsequent medical work-up has to rely on many more tests to confirm the presence of a diagnosis. The poor medical history exposes the patient, therefore, to more test-related risks, and prolongs the diagnostic process. All these downsides of a poor history ultimately increase medical resource utilization and healthcare expenditures.