Economic evaluation using mathematical models: the case of misoprostol prophylaxis.

Using misoprostol prophylaxis as an example, many of the methods employed in economic analyses that incorporate mathematical models were described. These included: decision analysis, cost effectiveness analysis (including incremental cost effectiveness analysis), one-way, multi-way, and probabilistic sensitivity analysis, and the estimation of quality adjusted life years for use in cost utility analysis. In the case of misoprostol prophylaxis, the cost effectiveness analysis demonstrated that, compared to the no prophylaxis alternative, prophylaxis cost an extra $650, on average, for every additional ulcer prevented, and was potentially cost saving for some high risk groups. The cost utility analysis demonstrated that prophylaxis resulted (on average) in modest additional costs and no additional quality of life benefits. Sensitivity analysis demonstrated that, at worst, prophylaxis reduced quality of life; at best, the incremental cost effectiveness ratio was $9333 for each quality adjusted life-year gained by prophylaxis compared to no prophylaxis. The results of the cost utility analysis also showed that prophylaxis may be cost saving in high risk groups, confirming the results of the cost effectiveness analysis. Finally, and perhaps most importantly, this analysis illustrated the importance of incorporating measures of health related quality of life into economic evaluation.