Reliability and validity of the Japanese version of the Self-Stigma Scale in patients with type 2 diabetes

Abstract

Background: Self-stigma has been highlighted and researched in relation to patients with chronic illnesses, as it may have a negative impact on their treatment adherence. However, self-stigma has not yet been investigated in patients with type 2 diabetes. In order to evaluate the extent to which patients with type 2 diabetes experience self-stigma, which may result in their poor self-care management, there is a need for a specific tool to measure self-stigma in patients with type 2 diabetes. This study assessed the psychometric properties of a Japanese version of the Self-Stigma Scale (SSS-J) in patients with type 2 diabetes. Methods: The reliability and validity of the SSS-J were evaluated using a consecutive sample of 210 outpatients with type 2 diabetes from university hospitals and from hospitals or clinics specializing in diabetes treatment. Confirmatory factor analysis was conducted to assess the factors theorized by the original Self-Stigma Scale. Cronbach's alpha for internal reliability and Pearson's correlations for construct validity were used for evaluation of psychometric properties. Pearson's correlations for test-retest reliability of the SSS-J were also performed. Results: Confirmatory factor analysis verified the three-factor structure of the SSS-J, consisting of cognitive, affective, and behavioral subscales. The model fit indices were as follows: the goodness-of-fit index was 0.78, the adjusted goodness-of-fit index was 0.70, the comparative fit index was 0.88, and the root mean square error of approximation was 0.07. Cronbach's alpha of the SSS-J was 0.96 (cognitive: alpha = 0.92; affective: alpha = 0.93; behavioral: alpha = 0.83). The SSS-J was associated with self-esteem (r = -0.43, p < 0.01), self-efficacy (r = -0.38, p < 0.01), and depressive symptoms (r = 0.39, p < 0.01). The 2-week test-retest reliability demonstrated satisfactory stability (r = 0.76, p < 0.01). Conclusions: The SSS-J is reliable and valid for assessment of the extent of self-stigma in Japanese patients with type 2 diabetes.