[Comment on the application of medical decision making].

There are three features in decision making in medicine. Decisions must be made on uncertain diagnostic and therapeutic information, a selected course of action may have an unwanted outcome, and finally, actions can not be retried from the beginning. We often assume that, by ordering a test, we can obtain more information to assist better decision making. It should be pointed out, however, that the test itself may be harmful and/or costly, may cause delay of treatment, and may misguide the decision by giving a false result. The benefit/risk ratio of choosing a test depends on the prior probability of disease, sensitivity and specificity of the test, and the outcome (utilities) of the correct and incorrect diagnosis. By drawing decision trees and making a sensitivity analysis, decision analysis helps to make the balance explicit.