Diagnostic criteria for schizophrenia: prognostic implications and diagnostic overlap

The files of 120 hospitalized patients who had participated in drug studies between 1964 and 1966 were examined without knowledge of the patient's subsequent history. These patients, who had originally been diagnosed by DSM-II criteria, were retrospectively diagnosed by New York Research Diagnostic Criteria (RDC), the New Haven Schizophrenia Index (NHSI), the St. Louis criteria, Bland and Orn's modification of the St. Louis critera, Schneider's first rank symptoms (FRS) criteria, and the 12-point "Flexible" system developed by the Washington field center of the International Pilot Study of Schizophrenia. By RDC criteria, 12 patients were diagnosed as major depressive disorders and the remaining 108 patients were diagnosed either schizophrenias, schizoaffective disorders, or unspecified functional psychoses. Of these 108, 97 were also diagnosed schizophrenic or schizoaffective by at least three other sets of critera. Ten-year followups were obtained on 82 (68%) of the 120 patients. Outcome was not significantly predicted by either presence or number of FRS, by an NHSI diagnosis of schizophrenia, or by a diagnosis of schizophrenia using the 12-point Flexible system with a 5-point cutoff. However, a significant relationship was found with the St. Louis criteria and the Bland-Orn score obtained from these criteria. An even higher correlation was found between followup and the Stephens-Astrup scale and the Strauss-Carpenter prognostic scale. RDC and DSM-II diagnoses were also significantly correlated with followup but to a lesser degree.