Clinical homogeneity of DSM-IV schizophrenic disorders

We investigated the lifetime fulfillment of five subcriteria of diagnostic criterion A in 94 inpatients with a definite diagnosis of DSM-IV schizophrenic disorder. Among the five diagnostic features captured by criterion A, only delusions were found to be almost universal, whereas of the remaining four, only hallucinations and negative symptoms occurred in more than half of all the cases. Overall, almost 60% of the 28 possible patterns of combination among the five subcriteria were found to be fulfilled although 60% of the cases were accounted for by only 4 patterns, which were also identified by means of a cluster analysis, as accounting for the totality of the cases. The first cluster was characterized by the fulfillment of subcriteria 1,2 and 5, the second by subcriteria 1 and 2, the third by subcriteria 1 and 5 and the fourth by subcriteria 1,2, and 3. The substantial clinical heterogeneity of the DSM-IV category of schizophrenic disorders with respect to their diagnostically characteristic features captured in criterion A is traced to the polythetic character of its five subcriteria.