[Principles of decisional analysis applied to the screening for occupational diseases: the example of occupational fluorosis].

In this paper, two oral presentations are combined. The first described the broad aspects of decision analysis and the second mentioned those medical data which need to be gathered in order to apply the model to industrial fluorosis. For this purpose, biological and medical observations were collected, both from workers of the aluminium industry and from controls. The five successive steps for building up a decision tree are then demonstrated, the aim of which being to evaluate the fitness of a screening strategy. A computer programme has been developed which may be applied both to occupational or non occupational diseases. Referring to industrial fluorosis, the computerized decision tree showed that screening with preshift urinary fluor, clinical and radiological signs, plus bone fluor rate is required, as soon as the risk corresponds to a 7% prevalence of the disease.