Each neural network was evaluated separately with a test set of cases from each database. With the combined database different neighbourhood methods were compared to find the optimal choice for this decision making problem. The acute appendicitis cases of the Finnish test data set were classified well with all the networks, but the cases of the German test set were difficult to classify for the Finnish network. The differences in the results of the Finnish and German databases suggest that there are differences in the data collection or patient population between centres. Therefore care must be taken when using decision support systems which have been developed in other centres.
Neural networks offer a method to evaluate differences between databases.
With the use of larger neighbourhoods the effects of the differences to the accuracy of the classification can be partly diminished.