Economic evaluation of health services. Concepts and methodology applied to screening programmes.

This methodological review seeks to explain the different levels of economic analysis, whose nature and use are often ill understood. These include analyses of cost-productivity, cost-effectiveness, and cost-benefit. The types of costs to be considered are then identified and classified into four groups according to whether they are direct or indirect, and visible or invisible. A numerical practical example of the cost-effectiveness of a breast cancer screening programme is used to demonstrate the techniques used in practice, and the types of problems and questions which may occur. The paper concludes that the development of epidemiological and economic models can make a significant contribution to the analysis of the complex interrelationships which prevail in the health services, and to the identification of aspects crucial for research and decision making concerning intervention strategies.