Application of the Comprehensive Assessment of At-Risk Mental States (CAARMS) to the Japanese population: reliability and validity of the Japanese version of the CAARMS.

Aim: The putative prodromal state of schizophrenia has been conceptualized as an at-risk mental state (ARMS), which is identified on the basis of ultra-high-risk (UHR) criteria, and the Comprehensive Assessment of At-Risk Mental States (CAARMS) has been developed as a specific instrument. However, the generalizability of CAARMS and the concept of ARMS have not been established. In this study, we tested the reliability and validity of the Japanese version of CAARMS (CAARMS-J). Methods: The participants were recruited from a specialized clinic for ARMS. The inter-rater reliability of CAARMS-J was examined. The Positive and Negative Syndrome Scale (PANSS) subscale scores and the basic symptoms of the CAARMS-J-defined UHR-positive group were compared with those of first-episode psychosis (FEP) and UHR-negative groups. The predictive validity was examined by following up the UHR-positive individuals. The 12-month transition rate to psychosis and the antipsychotics prescription rate were calculated. Results: The CAARMS-J showed good inter-rater reliability. The PANSS-positive symptoms subscale scores of the UHR-positive group were intermediate between the FEP and the UHR-negative groups, and the UHR-positive group scored higher than the UHR-negative group in some basic symptoms. The positive and negative symptoms scores of the CAARMS-J significantly correlated with the corresponding scores of the PANSS. After 12 months, 3 out of 28 (10.7%) UHR-positive cases had transitioned to psychosis and 11 (39.2%) individuals were prescribed antipsychotics. Conclusions: The CAARMS-J is a reliable and valid tool for assessing and detecting ARMS in Japanese clinical settings, suggesting that the concept of ARMS is applicable in Japan.