Quick Identification of the Risk of Psychosis: The Italian Version of the Prodromal Questionnaire-Brief.

BACKGROUND

Diagnosing people during the prodromal phase of an incipient psychosis can improve the chance of better outcome. In busy clinical settings, the ideal tool is a brief, easy-to-complete self-report questionnaire.

OBJECTIVE

To test the psychometric properties of the Italian version of one of the most used screening tools for the identification of the risk of psychosis, the Prodromal Questionnaire-Brief (PQ-B).

METHODS

Cross-sectional design. A convenience sample of college students was enrolled snowball procedure (n=243; men: 45%). After understanding and signing the consent form, the participants received a booklet containing the following questionnaires: the 21-item Prodromal Questionnaire-Brief (PQ-B); the 12-item General Health Questionnaire (GHQ-12), and the 74-item Schizotypal Personality Questionnaire (SPQ). Receiver operating characteristic (ROC) analysis was used to assess the capacity of the PQ-B to identify individuals at risk of psychosis as independently defined based on the combination of GHQ-12 and SPQ thresholds.

RESULTS

The Italian version of the PQ-B revealed good internal consistency, test-retest reliability, and adequate convergent and divergent validity. The Youden method retrieved a cut-off = 7 for the PQ-B frequency score and a cut-off = 22 for the PQ-B distress score. Both PQ-B scores had a perfect (99%) negative predictive value.

CONCLUSION

The PQ-B is a promising screening tool in two-stage protocols. The major advantage of the PQ-B is to exclude cases that are unlikely to be at risk of psychosis.