The elements of a formal decision analysis include the following:
(1) identification of an underlying set of management options, (2)
application of probabilities to uncertain events, (3) incorporation
of test results, and (4) inclusion of anticipated clinical outcomes
for alternative management options. Within the formal structure
of the process, referred to as a decision diagram or tree, numerical
values are inserted for the anticipated likelihoods of diagnoses,
test results, and treatment outcomes. The clinical end points can
be assessed in a variety of different ways, such as morbidity, mortality,
or quality of life. The alternative management options within the
decision diagram are referred to as clinical scenarios, each of
which is associated with an Expected Utility (or outcome). The Expected
Utilities of different scenarios are compared to arrive at the most favorable
approach to management. In many circumstances, precise estimates
of alternative diagnoses, test performance, or clinical outcomes
are unavailable. In these situations, the impact of assuming different
values for the unknown parameters can be explored through sensitivity
analysis.