Subtype stability in schizophrenia.

The authors examine the long-term stability of the subtypes of schizophrenia defined by four diagnostic systems. When all patients were considered, agreement between subtype assigned at index and follow-up was modest. This agreement increased considerably when only patients diagnosed as paranoid, hebephrenic, or catatonic at both index and follow-up were considered. As for individual subtypes, stability was highest for paranoid schizophrenia, intermediate for hebephrenia, and virtually absent for undifferentiated schizophrenia. The stability of paranoid schizophrenia was greatest when onset occurred after age 30. As length of follow-up increased, a larger proportion of patients were diagnosed as undifferentiated or residual.