DOWN-SYNDROME SERUM MARKER SCREENING - DECISION CRITERIA AND IMPLICITVALUES

Maternal serum markers assess the individual risk of giving birth to a fetus with Down syndrome. Because this information is a probability, and because of the infinite number of cut-off risks that can be adopte d, a decision criterion is needed to define a population screening pro gram. While a decision criterion for cut-off risks may refer to arbitr ations between risks, another criterion must be considered. This crite rion focuses on a societal perspective by comparing the costs of the p rogram to the expected benefits. We will first discuss the questions t hat are raised when assessing, in terms of cost-effectiveness, the con sequences of having adopted the policy maker's preferences for prenata l diagnosis referral. Subsequently, we will discuss the implicit value s attributed to the outcomes of the program when the societal point of view is reduced to societal profitability. This is accomplished by me ans of a cost-benefit analysis using the 'avoided costs' approach. The consequences of screening with 'double' and 'triple' tests were asses sed using a database made of 10108 observations, including 63 Down syn drome cases. For a cut-off risk of 1:250 (resulting in a 7% amniocente sis referral rate, regardless of the technique), conclusions in terms of decision making differ according to the effectiveness indicator. Al though a criterion based on resource allocation would promote the trip le test, cost-benefit analysis points out the impact on results of fac tors such as the amniocentesis related fetal losses or the introductio n of equity principles. (C) 1998 Elsevier Science Ireland Ltd.