Aim: The aim of this study was to investigate the demographic, illness and methodological factors associated with mean and median duration of untreated psychosis (DUP).
Methods: A systematic review and meta-analysis of the published studies of DUP and an examination of available DUP distributions.
Results: DUP was longer in samples with a higher proportion of patients with schizophrenia and was shorter in samples that included affective psychosis. Sex, age, and the methods of measuring the onset and end-point of DUP and the type of service in which the studies were performed did not contribute to the heterogeneity of the mean or median DUP values. Mean DUP is significantly prolonged by a small number of patients, and the median DUP is a poor indicator of the rate at which patients present.
Conclusions: The DUP of patients with affective and non-affective psychosis should be examined separately in order to make measures of DUP more meaningful and comparable, and DUP should be reported using more comprehensive measures. We suggest a method of reporting DUP based on the rate of presentation of first-episode psychosis patients rather than the length of DUP.