Long-term stability of subtypes in schizophrenic disorders: a comparison of four diagnostic systems

The long-term stability of subtypes of schizophrenic disorders in 148 narrowly defined schizophrenic patients according to four diagnostic systems was compared. The patients were investigated longitudinally for 23 years on average (range 10-50 years). Patients who experienced only one episode and those who were permanently hospitalised were excluded on methodological grounds. Of the remaining 100 patients, a total of 461 episodes were classified into various subtypes according to the criteria of DSM-III-R, ICD-10, the positive/negative dichotomy, and Schneider's first-rank symptoms. It was found that long-term stability of subtype in schizophrenic disorder was not the rule but the exception. The frequency of stable course was found to be depend on the type of the initial episode. In most cases a subtype change occurred within the first few years of the illness with no clear direction. In later stages of the illness the relative frequency of episodes predominated by negative symptomatology increased. The findings were similar for DSM-III-R, ICD-10 and positive/negative dichotomy. Only in patients beginning without first-rank symptoms were more stable than non-stable courses found. The results of this study do not support the assumption that stable subtypes are nosological or etiopathogenetic subentities of schizophrenic disorders.