Statistical cost-effectiveness analysis of two treatments based on net health benefits

Statistical methods for cost-effectiveness analysis (CEA) for two treatment s that mimic the deterministic optimal rules of CEA are presented. In these rules the objective is to determine the treatment with the maximal effecti veness whose unit cost is less than an amount, I, that a decision-maker is willing to pay (WTP). This is accomplished by identifying the treatment wit h the largest positive net health benefit (NHB), which is a function of lam bda, while controlling the familywise error rate both when the WTP value is given and when it is unspecified. Fieller's theorem is used to determine a region of WTP values where the NHBs of the treatments are not distinguisha ble. For each lambda outside of the confidence region, the larger treatment is identified. A newly developed one-tailed analogue of Fieller's theorem is used to determine the WTP values where a treatment's NHB is positive. Th e situation in which both treatments are experimental is distinguished from the case where one of the treatments is usual care. The one-railed confide nce region is used in the latter case to obtain the lambda values where the NHBs are not different, and determining the region of positivity of the NH Bs may be unnecessary. An example is presented in which the cost-effectiven ess of two antipsychotic treatments is evaluated. Copyright (C) 2001 John W iley & Sons, Ltd.