The Validity of the 16-Item Version of the Prodromal Questionnaire (PQ-16) to Screen for Ultra High Risk of Developing Psychosis in the General Help-Seeking Population

In order to bring about implementation of routine screening for psychosis risk, a brief version of the Prodromal Ques-tionnaire (PQ; Loewy et al., 2005) was developed and tested in a general help-seeking population. We assessed a consec-utive patient sample of 3533 young adults who were help-seeking for nonpsychotic disorders at the secondary mental health services in the Hague with the PQ. We performed logistic regression analyses and CHi-squared Automatic In-teraction Detector decision tree analysis to shorten the orig-inal 92 items. Receiver operating characteristic curves were used to examine the psychometric properties of the PQ-16. In the general help-seeking population, a cutoff score of 6 or more positively answered items on the 16-item version of the PQ produced correct classification of Comprehensive Assessment of At-Risk Mental State (Yung et al., 2005) psychosis risk/clinical psychosis in 44 % of the cases, distin