Screening for psychosis risk among help-seeking adolescents: application of the Italian version of the 16-item prodromal questionnaire (iPQ-16) in child and adolescent neuropsychiatry services

AIM: The 16-item Prodromal Questionnaire (PQ-16) is a versatile screen tool for routine screening of at-risk individuals. We wished to evaluate the psychometric properties of the Italian version of the PQ-16 (iPQ-16) in a sample of 72 help-seeking adolescents (age range 13-17 years) referred to child and adolescent neuropsychiatry services for diagnostic assessment. METHODS: Participants who completed iPQ-16 were subsequently interviewed with the Comprehensive Assessment of At-Risk Mental States (CAARMS) to confirm the psychosis high risk state. We then examined the diagnostic accuracy (sensitivity, specificity, positive and negative predictive values [PPV e NPV]) and concurrent validity between iPQ-16 and CAARMS using Cronbach's alpha and Cohen's kappa. We also tested the validity of the adopted iPQ-16 cut-offs through Receiver Operating Characteristic (ROC) curves plotted against CAARMS diagnoses and the 1-year predictive validity of the iPQ-16. RESULTS: Overall, the psychometric properties of the iPQ-16 were satisfactory. The iPQ-16 showed high internal consistency (Cronbach's alpha = .827) and acceptable diagnostic accuracy (77% sensitivity, 72% PPV) and concurrent validity (Cohen's k = 0.309). ROC analyses pointed to iPQ-16 total distress score of ≥10 as best cut-off. CONCLUSION: The iPQ-16 is a reliable and valid instrument for routine screening of at-risk individuals in Italian neuropsychiatry services.