Objective: The influential 1972 study by Manfred Bleuler on the long-term course of schizophrenic illness has been reconsidered. The authors tested the diagnosis of schizophrenia in all patients and investigated how the distribution of the types of illness course and outcome would change after exclusion of patients whose diagnosis of schizophrenia could not be confirmed by modern diagnostic standards.
Method: Clinical charts and Bleuler's research notes on the original sample were assessed, and all patients were rediagnosed with the help of DSM-IV, DSM-III-R, ICD-10, the Research Diagnostic Criteria (RDC), Schneider's criteria, and an operationalized version of the criteria of Eugen Bleuler.
Results: The diagnosis of schizophrenia was not confirmed in about 30% of the sample; the majority of these patients were rediagnosed with schizoaffective disorder. High diagnostic agreement was found between DSM-IV, DSM-III-R, ICD-10, and RDC; there was much less agreement with Bleuler's and Schneider's criteria. After exclusion of patients whose schizophrenia diagnosis was not confirmed, the proportion of patients with undulating course and recovery slightly decreased, and the proportion of patients with severe end state slightly increased. Nevertheless, the distribution of the types of long-term course did not significantly change, and even among patients with strictly defined schizophrenia, half had an undulating course with remissions and 12%-15% recovered.
Conclusions: Schizophrenic illness remains heterogeneous with regard to illness course and outcome even when narrowly diagnosed with the help of modern operationalized diagnostic criteria. Contemporary differentiation between schizophrenic and schizoaffective disorders is prognostically valid.