The use of decision analysis in the pharmacoeconomic evaluation of an antidepressant: a cost-effectiveness study of nefazodone.

A decision model can be a useful tool for evaluating the cost-effectiveness of a drug during research and development, before the drug is marketed. Decision analysis provides a structured process for comparing the costs and consequences of a new drug with those of standard drug therapy. This article introduces the use of a decision model and discusses the advantages and disadvantages of such a model. A cost-utility study of nefazodone, a new antidepressant, illustrates the application and interpretation of decision models. Decision analyses using data from clinical trials are a great potential source of information on the economic impact of new drugs. However, the development and use of such models require tolerance of uncertainty, the ability to represent complex relationships accurately, awareness of all factors that might influence the results, and a willingness to validate the model to the extent that validation is possible. The disadvantage of clinical decision models is that the findings are only as reliable as the information on which the model is based. Nevertheless, sensitivity analyses can be used to vary any information in question and assess the impact of that variation on the findings of the analyses. The advantage of clinical decision models is that they encourage the consideration and explicit representation of all pertinent inputs and outcomes. They clearly differentiate knowledge supported by data from assumptions, and compel assessment of the effect of those assumptions on the findings. The cost-effectiveness of nefazodone relative to standard treatment for major depression was evaluated using a decision model that simulated the lifetime direct medical costs and health outcomes associated with nefazodone and two comparators, imipramine and fluoxetine. The model included the possible clinical management pathways and the use of medical resources in treating major depression from early adulthood until death. Sensitivity analyses were performed to determine the impact of variation in model parameters on the results of the model. Using the base case assumptions of the model, which included parity of pricing with fluoxetine, nefazodone was found to be a cost-effective treatment for major depression.