[Cost of illness studies as a basis for decision making].

Definitions and methods for cost of illness studies are explained: costs, direct costs, indirect costs, intangible costs, the human capital method and the willingness to pay approach. Devaluing the long-term health benefits from prevention by constant discount rates is questioned. The development and the state of the art of cost of illness studies at a national level in Germany are discussed. As an example the newly developed cost of illness study of the Federal Statistical Office with direct and indirect costs of circulatory diseases is presented. Reasons for the benefit of cost of illness studies for decision making are given in the context of costs of illness and aging.