Validation of the Chinese version of the Somatic Symptom Scale-8 in patients from tertiary hospitals in China
Tao Li, Jing Wei, Kurt Fritzsche, Anne Toussaint, Lan Zhang, Yaoyin Zhang, Hua Chen, Heng Wu, Xiquan Ma, Wentian Li, Jie Ren, Wei Lü, Rainer Leonhart
Abstract
Objective To validate the Chinese language version of the Somatic Symptom Scale-8 (SSS-8) in a sample of outpatients attending tertiary hospitals in China. Materials and methods A Chinese language version of the SSS-8 was completed by outpatients ( n = 699) from psychosomatic medicine, gastroenterology/neurology, and traditional Chinese medicine clinics of nine tertiary hospitals between September 2016 and January 2018 to test the reliability. The Patient Health Questionnaire-15 (PHQ-15), the Somatic Symptom Disorder–B Criteria Scale (SSD-12), the Patient Health Questionnaire-9 (PHQ-9), the General Anxiety Disorder-7 (GAD-7) scale, the Medical Outcome Study 12-item Short Form Health Survey (SF-12) and the World Health Organization Disability Assessment Schedule (WHO DAS 2.0) were rated to test construct validity. The criterion validity was tested by using the Semi-structured Clinical Interview for DSM-5 (Research Version) (SCID-5-RV) for somatic symptom disorder (SSD) as the diagnostic gold standard to explore the optimal cutoff score of the SSS-8. Results The average age of the recruited participants was 43.08 (±14.47). 61.4% of them were female. The internal consistency derived from the sample was acceptable (Cronbach α = 0.78). Confirmatory factor analyses resulted in the replication of a three-factor model (cardiopulmonary symptoms, pain symptoms, gastrointestinal and fatigue symptoms) (comparative fit index = 0.95, Tucker-Lewis index = 0.92, root mean square error of approximation = 0.10, 90% confidence interval = 0.08–0.12). The SSS-8 sum score was highly associated with PHQ-15 ( r = 0.74, p < 0.001), SSD-12 ( r = 0.64, p < 0.001), GAD-7 ( r = 0.59, p < 0.001), and PHQ-9 ( r = 0.69, p < 0.001). The patients with more severe symptoms showed worse quality of life and disability The optimal cutoff score of SSS-8 was 9 (sensitivity = 0.67, specificity = 0.68). Conclusion Our preliminary assessment suggests that the Chinese language version of the SSS-8 has reliability and validity sufficient to warrant testing further in research and clinical settings.