Prevalence of psychoses on reception to male prisons in New South Wales.

OBJECTIVE: To estimate the prevalence of psychotic illnesses among men received to prisons in New South Wales. The study also sought to estimate the sensitivity and specificity of the psychosis screener in the Composite International Diagnostic Interview (CIDI-Auto).
METHOD: The study was part of a larger study on psychiatric disorder in men received to New South Wales prisons. Using a structured questionnaire, the CIDI-Auto (modified), which included screening questions for psychotic illness, the prisoners who gave positive responses to the screening questions for psychosis as well as any subjects considered by the experienced clinicians performing the CIDI-Auto interviews to show features of a psychotic illness, were referred to the researchers for a clinical assessment. The clinical assessment included a review of all available information.
RESULTS: Of the prisoners, 5.1% were thought to have definite psychotic illness and 1.9% to have possible psychotic illness. The psychosis screener was found to be neither sensitive nor specific.
CONCLUSIONS: The rate of psychotic illness among people remanded to New South Wales prisons is between 10 and 14 times the rate found in a similar study in the wider community. The poor performance of the psychosis screener suggests that screening for psychotic illness on reception to prisons should be performed by clinically trained staff.