Rationale and design

BACKGROUND: This paper sets out the rationale for the PRiSM Psychosis Study, and the research design used. Nine accompanying papers present the main results. The questions addressed by the PRiSM Psychosis Study are: can the gains of experimental studies which have demonstrated benefits arising from treatment by community mental health teams be translated to routine settings? If so, are the benefits diluted in ordinary clinical practice? What are the costs? METHOD: A prospective nonrandomised controlled trial of two types of community mental health service, in two phases: case identification followed by patient interviews. For the case identification the research team conducted the complete ascertainment of all prevalent cases of psychosis in the two study catchment areas in the index year (1991-1992). From all 514 patients with psychotic disorders thus identified, 302 were randomly allocated for interview, along with a key informant clinician and a carer. Interviews were under taken at two time points, two years apart. RESULTS: This paper presents the socio-demographic, clinical and ethnic characteristics of the patients. CONCLUSIONS: The people with psychosis interviewed for the PRiSM Psychosis Study are representative of the whole epidemiologically based patient population identified.