Psychometric Evaluation of the Symptom-Checklist-K-9 Among US Working-Age Adults With Psychiatric Disabilities

Purpose: The Symptom Checklist 90-Revised (SCL-90-R; Derogatis, 1992) is a widely used self-report measure of psychiatric symptoms (Prinz et al., 2013), but it is longer than many screening measures used in certain settings. Recently, a nine-item form of the SCL-90-R, the Symptom-Checklist-K-9 (SCL-K-9), has been gaining traction despite the limited research examining its psychometric properties in the United States. The purpose of this study is to conduct a psychometric evaluation of the SCL-K-9 scores in U.S. working-age adults with psychiatric disabilities. Design: Six hundred and thirty participants with self-reported psychiatric disabilities completed the SCL-K-9 and other psychosocial self-report measures. Confirmatory factor analysis (CFA) was conducted to evaluate the SCL-K-9 scores' dimensionality. Coefficient omega was used to assess the scores' internal consistency. Convergent and discriminant validity were assessed by examining the strength and direction of correlation coefficients between the SCL-K-9 and other psychosocial measures. Measurement invariance across sex, age, and primary diagnostic groups was also examined. Results: CFA revealed a one-factor solution with satisfactory reliability (coefficient omega = .828). Convergent validity was supported by the relatively high correlation coefficients between the SCL-K-9 with neuroticism, self-stigma, and psychiatric disability acceptance, and discriminant validity by relatively low correlation coefficients with perceived social stigma and hope. Full measurement invariance for sex and partial invariance for diagnostic groups was supported. Conclusions: Overall, this study provides preliminary reliability and validity evidence for the SCL-K-9 scores among U.S. working-age adults with psychiatric disabilities. Further investigation is warranted to support its use for research and treatment progress monitoring in recovery-oriented care.