Translation and Validation of the Japanese Version of the Trait and State Post-Event Processing Inventory

In this study, we translated the Trait and State versions of the Post-Event Processing Inventory (PEPI) into Japanese and examined their psychometric properties. One thousand participants, comprising three subsamples, completed the questionnaires. Confirmatory factor analyses supported a bi-factor model, comprising one general factor and three theoretically derived subfactors (“Frequency,” “Self-judgment,” and “Intensity”), for the State and Trait versions of the scale. However, both versions were essentially unidimensional, and scoring based on subfactors lacked support. Additionally, we found preliminary evidence for the test–retest reliability; internal consistency; and concurrent, convergent, divergent, incremental, and predictive validity of both versions. Furthermore, participants with self-reported diagnoses of social anxiety disorder exhibited higher scores on both the PEPI-Trait and PEPI-State than healthy controls. Our findings suggest that the Japanese versions of the PEPI-Trait and PEPI-State may become useful alternatives to existing measures of post-event processing in Japan.