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.