Psychometric Properties of Chinese Version of Work and Social Adjustment Scale for Outpatients With Common Mental Disorders: Classical Test Theory and Rasch Analysis

Abstract

OBJECTIVES: To determine the psychometric properties of the Chinese version of the work and social adjustment scale (CWSAS) in outpatients with common mental disorders, and to evaluate the correlations of CWSAS with Physical Health Questionnaire-9 (PHQ-9), General Anxiety Disorder-7 (GAD-7), World Health Organization Five Well-being Index (WHO-5), and Chinese version of the Perceived Stress Scale-10 (CPSS-10). METHODS: Forward and backward translations of the CWSAS was performed. Between October 2018 and March 2020, 252 outpatients with a common mental disorder who had a job or a job plan were recruited from two psychiatric centres in Hong Kong. Participants were asked to complete the CWSAS, PHQ-9, GAD-7, WHO-5, and CPSS-10. Classical test theory and Rasch analysis were undertaken to determine the psychometric properties of the CWSAS and its correlations with other tools. RESULTS: Principal component analysis revealed that the CWSAS was a one-factor structure and showed adequate convergent and discriminant validities, internal consistency, item-total correlation, and inter-item correlation. There was a significant group difference in terms of employment status. CPSS-10 and PHQ-9 were predictors for CWSAS score. The CWSAS was a distinct factor among other outcome measures. Rasch analysis indicated that the CWSAS was well-targeted and unidimensional. The CWSAS had an adequate person separation index, item separation index, person reliability, and item reliability. No categorical disordering was found, whereas inadequate adjacent threshold distance was reported. The item of ability to work indicated a noticeable differential item functioning in employment status and main source of finance. CONCLUSION: The CWSAS is psychometrically appropriate to measure functional outcomes in outpatients with common mental disorders.