Reliability and validity of the Japanese semistructured interview version of the Early Signs Scale (ESS-JI) for outpatients with schizophrenia (study 1)

The purpose of this study was to develop a semistructured interview for the Japanese version of the Early Signs Scale (ESS-JI), as well as to examine its reliability and validity. We conducted a cross-sectional study in Japan. Participants were recruited from a psychiatric clinic. The survey included 25 participants with schizophrenia; of these, 21 participants gave informed consent. For the analysis, we used data from 15 outpatients who had no missing values on the ESS-JI. Of the participants, 70% were female, and the mean age was 41.2 years. The ESS-JI was developed by the authors using a translation-back-translation procedure. Internal consistency was assessed by Cronbach's alpha coefficients, and test-retest reliability was assessed by Pearson's correlation coefficients. Correlations with other scales, such as the Behaviour and Symptom Identification Scale (BASIS-32) and the Self-Efficacy for Community Living Scale (SECL), were used to examine the concurrent and construct validity of the ESS-JI. Cronbach's alpha coefficients were high for the ESS-JI. Pearson's correlation coefficients also indicated good test-retest reliability. The ESS-JI was significantly and positively correlated with the BASIS-32. In contrast, the ESS-JI had a significant negative correlation with the SECL. This study confirmed the reliability and validity of the ESS-JI for outpatients with schizophrenia.