Classifying the courses of schizophrenia.
The purpose of this review was to examine current strategies for classifying the courses of schizophrenia. Although a number of course classifications have evolved over the past two decades, the field has not addressed fully the complex issue of course description. This review compared previously published prototypes for describing the long-term courses of schizophrenia to identify variations and consistencies in course descriptions. Across investigations, differences were found in the number of courses described, in the structure of course categories, in the relative emphasis on syndrome symptoms versus syndrome change, and in documenting specific course features (i.e., illness onset, illness outcome, and types of symptoms). Interstudy comparisons of long-term illness patterns therefore are limited and cumulative statements on prognosis will remain problematic until some standardization is introduced. A minimal set of course parameters that should be documented in future studies include (1) the rate of syndrome onset; (2) postonset patterns of psychotic and residual symptoms; (3) postonset patterns of social, work, and self-care activities; and (4) outcome. Descriptive domains for assessing these parameters are offered. Future research should be directed toward (1) developing a standard schizophrenia course classification that is more representative than the current DSM and Research Diagnostic Criteria classifications; (2) using a broadened domain of symptom patterns to characterize short- and long-term courses of schizophrenia; (3) increasing course reports with a focus on patients who demonstrate intermediate illness courses; and (4) exploring factors that converge with particular course types.