Development and validation of the Japanese version of the Epilepsy Stigma Scale in adults with epilepsy

Background: Self-stigma is considered to have immensely negative influences on the living and psychological states in patients with epilepsy. Understanding the stigma experienced by patients with epilepsy is essential considering its negative impact on their treatment and quality of life (QOL). However, few sufficiently validated self-report instruments are available to evaluate self-stigma in patients with epilepsy. The Epilepsy Stigma Scale (ESS) is one of the most commonly used self-reported questionnaires available to evaluate self-stigma in patients with epilepsy. The present study translated the ESS into Japanese to validate the Japanese version of the ESS (ESS-J) in Japanese adults with epilepsy. Methods: The study included 338 patients with epilepsy (166 men, aged 18–75 years) who underwent comprehensive assessment including long-term video-electroencephalography monitoring, neuroimaging studies, and neuropsychological and psychosocial assessments in the Tohoku University Hospital Epilepsy Monitoring Unit. This study consisted of two phases: (1) translation of the ESS into Japanese using the back-translation technique; and (2) statistical analysis of the ESS-J to evaluate the factor structure, reliability, and validity. Results: The 2-factor model achieved acceptable fit to the data: χ² = 161.27, df = 34, p < 0.01, comparative fit index = 0.929, root mean square error of approximation = 0.105, standardized root mean squared residual = 0.047, Akaike's information criterion = 203.27 and, Bayesian information criterion = 283.56. These two subscales were named enacted stigma and felt stigma based on the theoretical model of self-stigma. We found the ESS-J to have acceptable internal consistency as follows: enacted (7 items; α = 0.88) and felt stigma subscale (3 items; α = 0.82). The concurrent validity was confirmed by adequate correlation with other related instruments. Both enacted and felt stigma had positive and moderate correlations with depression as measured by the Neurological Disorders Depression Inventory for Epilepsy (r = 0.44, p < 0.01; r = 0.41, p < 0.01, respectively) and with anxiety as measured by the Generalized Anxiety Disorder -7 (r = 0.48, p < 0.01; r = 0.38, p < 0.01, respectively). Conclusion: The ESS-J demonstrated acceptable validity and reliability. The present study provided preliminary evidence about the psychometric properties of the ESS-J, indicating the reliable factorial structure, adequate internal consistency, and satisfactory construct and concurrent validity. Measurement of the two types of self-stigma may offer a useful tool for clinical interpretation of patients’ psychological state throughout epilepsy care, and as one of the patient-reported outcomes in QOL research.