Reliability and validity of the Korean version of the comprehensive assessment of at-risk mental states

Aim Although the comprehensive assessment of at-risk mental states (CAARMS) is one of the most widely used instruments for identifying individuals meeting the criteria for ultra-high risk (UHR) of developing psychosis, the psychometric properties of the Korean version of the CAARMS (CAARMS-K) have not been studied to date. Thus, we tested the reliability, validity, and factor structure of the CAARMS-K in a Korean population. Methods The CAARMS-K was administered to 96 UHR individuals. The inter-rater reliability and internal consistency of the CAARMS-K were evaluated. In addition, its factor structure was investigated using principal-axis factor analysis. Concurrent validity was examined by comparing the extracted CAARMS-K factors with the five factors of the positive and negative syndrome scale (PANSS) using Spearman's correlation tests. The percentage of transition to psychosis was examined at 1- and 2-year. Results The inter-rater reliability was good (intraclass correlation = .89), and the internal consistency was acceptable (Cronbach's alpha = .812). A five-factor solution demonstrated the best simple structure and accounted for 43.1% of all-item variance. The five factors extracted from the factor analysis were similar to the PANSS five factors and significantly correlated with the factors of the PANSS. Among the 96 UHR individuals, 11 (11.5%) and 17 (17.7%) developed psychotic disorders during the 1- and 2-year follow-up, respectively. Conclusions The CAARMS-K is a reliable and valid instrument for the assessment of UHR individuals in Korea.