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.