Review of the operational definition for first-episode psychosis.

AIM: Given the growing interest in the study of first-episode psychosis, clinical and research programmes would benefit from a conceptual clarification of how to operationalize 'first-episode psychosis'. We review the variety of definitions in use and discuss their relative merits with respect to both clinical (e.g. early treatment) and research (e.g. obtaining meaningfully homogeneous populations) agendas.
METHODS: We completed a selective review of the literature to investigate how first-episode psychosis was operationally defined.
RESULTS: Operational definitions for 'first-episode psychosis' fall largely into three categories: (i) first treatment contact; (ii) duration of antipsychotic medication use; and (iii) duration of psychosis. Each definitional category contains a number of underlying assumptions that contribute to the strengths and weaknesses of the definition.
CONCLUSIONS: The term 'first-episode psychosis' as used within clinical and research settings is misleading regardless of which operational definition is used. This term is typically used to refer to individuals early in the course of a psychotic illness or treatment rather than individuals who are truly in the midst of a first 'episode' of illness. The alternative of 'recent-onset psychosis' with related definitions based on 'duration of psychosis' is proposed. Based on this review, we provide suggestions with regard to the overarching pragmatic consideration of setting up a clinical service that can attract and assemble a population of early psychosis patients for the related purposes of treatment and research.