[Economic analysis of the dissemination of a medical innovation: prenatal diagnosis by early amniocentesis as an example. Part 2. Facilitating decision making in public health for optimal dissemination of an innovation].

Only a specific public health policy can resolve the technical, ethical, and financial problems posed by the diffusion of prenatal diagnosis by amniocentesis for the prevention of Down's syndrome. The purpose of this article is to facilitate decision making in this field by evaluating the costs and benefits associated with the different prevention strategies. Beginning with projections of the number of Down's syndrome births to be expected among women of 35 and older to the year 2000 (assuming that no prenatal diagnosis are made), various objectives combining the age of the target population and usage rates are presented and discussed. An evaluation of the overall costs of prenatal diagnosis and caring for Down's syndrome patients shows that a policy reaching a 50% usage rate for women 38 and older would save up to 66 millions French francs (using the 1981 franc value). On the other hand, it is shown that lowering the incidence of Down's syndrome in a target population of women over 35 to the level of the younger population would imply a usage rate of at least 80%. This goal is unrealistic unless amniocentesis were to become a compulsory examination. In such case, women would be deprived of an essential freedom, in view of the related ethical issues. The authors lastly discuss the different means of increasing usage rates without inhibiting women's freedom of choice.