The Reliability and Validity of the Korean Version of the Structured Interview for Prodromal Syndrome

OBJECTIVE The Structured Interview for Prodromal Syndrome (SIPS) from Yale University is intended to diagnose prodromal syndrome of psychosis and to measure the severity of prodromal symptoms. Here, a Korean version of SIPS is presented, and its reliability, validity, and factor structures are examined using a representative Korean sample. METHODS The Korean version of SIPS was administered to 40 participants over a period of 1 year. The inter-rater reliability and internal consistency of the SIPS were then evaluated. In addition, its factor structure was investigated using principal-axis factor analysis. Concurrent validity was explored using Pearson correlation coefficients with the Positive and Negative Syndrome Scale (PANSS). RESULTS Of the 40 subjects, 12.5% developed psychotic disorders during the 1-year follow-up period. Inter-rater reliability was good (intra-class correlations=0.96), and internal consistency was acceptable (Cronbach's alpha=0.83). A three-factor resolution displayed the best simple structure and accounted for 52.6% of all item variance. Factors 1 and 2 showed strong correlations with negative symptoms and cognitive dysfunction, respectively, on the PANSS. Factor 3 was not correlated with any factor on the PANSS. CONCLUSION The Korean version of SIPS is a reliable instrument for the assessment of prodromal symptoms in subjects and may be used to evaluate prodromal psychosis.