Discriminant and Bayes Analysis in the Differential Diagnosis of Crohns Disease and Proctocolitis

Proctocolitis and colonic Crohn’s disease have not yet been precisely differentiated and the existence of the latter is still disputed. The study reported here is concerned with identification of the clinical features characterising patients diagnosed clinically as suffering from one or other of these diseases. A stepwise linear discriminant analysis of 91 possible indicants showed that seven were sufficient to discriminate between the two clinical groups. A further analysis of the patterns of these seven by a Bayesian method which takes account of the interdependence of the indicants showed that only five indicants were necessary for discrimination. The Crohn’s disease patients fell into a much greater variety of patterns than those with proctocolitis most of which fell into only one pattern. It is suggested that this use of linear discrimination to reduce the number of indicants combined with a subsequent analysis of the patterns of these indicants might be useful in other diseases.