Test-Treatment Threshold

How can physicians decide whether a particular treatment could provide benefits to a patient rather than harm by unnecessary treatment? If a physician has 100% confidence that a particular patient has a disease (100% pretest probability), the physician should treat the patient. In contrast, a physician would not treat the patient if he or she had 100% confidence that the patient did not have the disease (0% pretest probability). Unfortunately, the pretest probability is not always 0% or 100% but usually lies somewhere in between these numbers, which is usually called a gray area. Taking potential adverse events into consideration, what estimated probability of disease do physicians need to decide whether or not to treat?

Threshold analysis is a mathematical approach to determine the answer. The ...