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

Abstract

Objective To examine the reliability and validity of the Korean version of the 16-item Prodromal Questionnaire (KPQ-16) in non-help-seeking university students. Methods Among 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. Results 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.

Validation of the Korean Version of the 15-Item Community Assessment of Psychic Experiences in a College Population

“…In this study, the PPV of the CAPE-15 distress score was improved (32.4%) compared with previous screening tools, 6,7,10 but it was still relatively low for a screening tool with strong predictive power. Nevertheless, when a tool is used to screen for a serious, low-prevalence disease, such as psychosis, the chosen cutoff point should provide good sensitivity, even when the PPV is low or the false-positive rate is high.…”

“…In this study, the cutoff score of the mKPQ-16 for identifying psychosis risk was the same and its PPV was similar to those of our previous validation study for the mKPQ-16. 7 This suggests that the process used in the current study was credible and showed the stability of the mKPQ-16 as a screening tool. The sensitivities and specificities of the PQ-16, PQ-B, and ESI were below 80% in previous studies, 6,7,10 but those of the CAPE-15 in this study were 91.7% and 85.2%, respectively.…”

“…The modified Korean version of the PQ-16 includes three additional item drawn from the ESI, in addition to the 16 items of the original instrument. 7,8 The original CAPE is a self-report screening questionnaire that comprised 42 items. 14 The CAPE-15 is a shorter subscale that has been widely used as a screening tool to identify people at UHR in a clinical setting.…”

“…Of the initial study population, 1,225 (70.0%) consented to potentially being contacted a second time and thus provided their phone number. In line with the procedure of our previous validation studies, 7 individuals with CAPE-15 scores ≥4 (n=224, 18.3%) and with depressive symptoms regardless of CAPE-15 score (n=76, 6.2%) were selected for semi-structured interviews. Of the subjects for whom the next investigation was indicated (n=300), 191 (63.7%) participated in a semi-struc-tured interview.…”

“…Therefore, to increase the PPV of the PQ-16, we modified Korean version of the PQ-16 (mKPQ-16) by adding three ESI items (ideas of reference, cognitive impairment, and persecutory ideas). 7 The Community Assessment of Psychic Experiences-Positive 15-items scale (CAPE-15) is another brief, valid screening tool used to identify people at high risk of psychosis in the community. 12 This study examined the reliability and validity of the Korean version of the CAPE-15 in university students.…”