Development of a formal structure for clinical management decisions: a mathematical analysis.

Decision theory and the calculating power of the computer now enables us to contemplate the development of formal methods for making decisions about clinical management. In the simplest model, it is first necessary to define all treatment decisions as an exhaustive and mutually exclusive set and similarly to define the set of consequences or outcomes of treatment. The probability of each outcome conditional on treatment has to be estimated and this consequent state of health has to be quantified as a utility. Possible methods of estimating utilities of states of health are discussed and the construction of a unidimensional utility function based on a sequence of wagers. The states of health consequent on severe brain damage can only be described multidimensionally and the model has to be extended to include this case. While such a model would allow simple treatment decisions to be formalized, it could not decide whether the cost of treatment was worth while nor whether it would pay to carry out further investigative tests and thus buy more evidence. If these additional variables are to be included in the model, it is necessary to introduce the motion of an equivalence between monetary values and utilities. This implies attaching a monetary value to any given state of health.