Validation of the Korean version of the 16-Item Prodromal Questionnaire in a Non-Help-Seeking College Population

Objective-To examine the reliability and validity of the Korean version of the 16-item Prodromal Questionnaire (KPQ-16) in nonhelp-seeking university students. Methods-aAmong 2,246 university students participated in the initial screening, 257 subjects with KPQ-16 scores ≥4 were interviewed.The criteria for ultra-high risk (UHR) of psychosis of the Comprehensive Assessment of At-Risk Mental States (CAARMS) were the gold standard for diagnosis. An exploratory modified version of the questionnaire (mKPQ-16), to which three items from the Eppendorf Schizophrenia Inventory were added, was also used to compensate for items on thought and cognitive problems. Result-Seventeen subjects met the CAARMS criteria for UHR of psychosis. The area under the receiver operating characteristic curve (AUROC) was highest for the mKPQ-16 total score (AUROC=0.831, p<0.001). The use of cutoff total scores of 7 for the mKPQ- 16 and 6 for the KPQ-16 resulted in the best balance of sensitivity (76.5% and 64.7%, respectively) and specificity (75.4% and 71.2%, respectively). Conclusion-The Korean versions of the PQ-16 are good instruments for screening for psychosis risk in university students. This validation of a questionnaire version with a small number of items may make it feasible to screen large numbers of young adults in the community.