[An approach to hospital regionalization: the case of Liege]

Since the early 70's, the policy regarding public hospitals in Belgium has been oriented towards distinguishing various geographical regions (within the country) and, within each region, various levels of technology, each having a specific function. But how does one delineate a region? The application of a log-linear model, first introduced by Birch (1963), shows that in the vast area of Liège and its surrounding localities, there are several autonomous sub-regions. Analysis of flows of patients from their "commune" of residence to the "commune" of the hospitals where they are admitted indicates that: (i) admissions are very frequent within each sub-region; (ii) there are strong exchanges between certain sub-regions, in particular between Huy and Waremme and between Verviers and Stavelot-Malmedy. Moreover, use of the model of quasi-symmetry, introduced by Caussinus (1965), suppresses the effect of the flows within each sub-region and illustrates the specific attractiveness of the city of Liège and its university hospital. Finally, the projection of interactive flows between Greater Liège and its surrounding regions shows that the former hosts 93% of the hospital admissions of its residents. Hospital admission is a sound example of the urban function of which geographic strength may be of interest for delineating regions within countries.