To test or not to test--to treat or not to treat: the decision-threshold approach to patient management.

The inability to consider explicitly factors that should enter into clinical judgment compromises physician efforts to make cost-effective decisions regarding diagnostic testing and treatment. The authors describe the decision-threshold approach, a decision-analysis strategy that helps physicians identify an optimal test-treatment decision based upon the prior probability of disease, the characteristics of the test (sensitivity, specificity, risk), and the benefits/costs of treatment. They also present a microcomputer graphics program that makes the decision-threshold approach readily available to physicians.