A self-reported instrument for prodromal symptoms of psychosis: Testing the clinical validity of the PRIME Screen—Revised (PS-R) in a Japanese population

Abstract

Objective: Early intervention for psychosis requires an easy, useful assessment instrument to identify subjects with prodromal symptoms at an early stage. The aim of this study was to test the clinical validity of the PRIME Screen—Revised (PS-R), a 12-item self-reported instrument for prodromal symptoms of psychosis, by comparing the results for a non-clinical population with those for a clinical population. Method: The PS-R was administered to 1024 subjects (496 students and 528 outpatients). Of the 528 patients, 115 were randomly recruited and tested using the Structured Interview for Prodromal Syndromes (SIPS) to determine the concordant validity of the PS-R. The predictive validity of the PS-R was measured by determining the transition rate to psychosis during a 6-month follow-up period. Results: The specificity and sensitivity of the PS-R, using the SIPS as a gold standard, were 0.74 and 1.00. The concordant validity of the PS-R against the SIPS was 0.43. The predictive validity of the PS-R and the SIPS, defined as the transition rate to psychosis, were 0.11 and 0.25, respectively. None of the patients with negative PS-R results developed psychosis. Conclusions: Our findings showed that the PS-R was highly valid and that its usage is feasible in both general practice and clinical settings. This self-reported instrument represents a useful screening tool for alerting clinicians to subjects with psychotic prodromal symptoms.