Reliability and validity of methods for measuring the duration of untreated psychosis: a quantitative review and meta-analysis.
The duration of untreated psychosis (DUP) has been associated with a wide range of clinical outcomes, and is considered to be one of the key parameters in managing clinical high risk and first episode psychosis patients. However, considerable discrepancies exist in the way that DUP is estimated in different studies. There is no standard or consensus on which method is most reliable and valid for assessing DUP. This review aimed to quantitatively assess different DUP measurement instruments and definitions by comparing their inter-rater reliability, and their strength of validity in predicting biological and clinical outcomes. Nine instruments designed for measuring DUP were found. Their inter-rater reliability were found to be adequate to excellent, although quite varied. This analysis did not show that any instrument was clearly outstanding compared to the others, although the limited available data do not exclude this possibility. DUP was also significantly associated with a range of outcomes, although mostly with small effect sizes. However, non-instrument based, ad hoc clinical interviews remained the most common way of measuring DUP. Definitions of onset of psychosis and onset of treatment were inconsistent among studies. This review did not find quantitative evidence to support the use of one instrument over another. DUP remains a promising modifiable risk factor for a range of long-term clinical outcomes. Future research should quantify and improve the reliability and validity of the structured instruments for DUP measurement.