Study design and settings
This study is a secondary analysis of a dataset that was collected for a previous multicenter cross-sectional study that was conducted from May 2016 to March 2017 in outpatient clinics of nine tertiary hospitals in North, North-Central, East, Central, and West China (Beijing, Jincheng, Shanghai, Wuhan, and Chengdu) . The modern biomedical setting was represented by the neurology and gastroenterology departments, the Traditional Chinese Medicine (TCM) department represented the TCM setting, and the psychological medicine department represented the psychosomatic medical settings. For each setting, 220 patients were supposed to be recruited.
The screening days at each center were randomly determined. All patients who were admitted to one of the study departments were approached for participation in the study using an informational hand-out. An informed consent form was used to explain the aims of the study to the patients. The patients were fully informed that their participation was voluntary, that the data would be analyzed anonymously, and that there were no disadvantages in case of refusal to participate.
The inclusion criteria were: 1) >18 years old 2) visiting for treatment (i.e., not only picking up a prescription); 3) able to read and write; and 4) signed the written consent form. The exclusion criteria were: 1) language barrier; 2) limited writing skills; 3) cognitive impairment; 4) psychosis; or 5) acute suicidal ideation.
Smoking was classified as never smoking, former smoker, and current smoker. Drinking was classified as never drinking, drinking only socially, drunk in the past but quit drinking, and currently drinking>3 days/week. Exercise was classified as >2 h/day, 1-2 h/day, <1 h/day, and no physical exercise.
Figure 1 presents the study process. All patients who provided written informed consent filled in questionnaires for general information and quantitative assessment of psychopathology: 1) Patient Health Questionnaire 15 (PHQ-15) for the number and severity of somatic symptoms; 2) Somatic Symptom Scale-8 (SSS-8) for the somatic symptom burden; 3) Patient Health Questionnaire 9 (PHQ-9) for depression; 4) General Anxiety Disorder-7 (GAD-7) for anxiety; 5) Whiteley-7 for health-related anxiety (WI-7); 6) WHO Disability Assessment Schedule (WHO-DAS 2.0); 7) Somatic Symptom Disorder B-criteria (SSD-12); 8) 12-item short-form health survey (SF-12) for quality of life; 9) questions on health care utilization; and 10) sociodemographic data (age, sex, level of education, marital status, etc.).
The PHQ-15 was validated in Chinese for somatic symptoms [14, 15]. SSS-8 is a self-rating scale used to quantify the somatic symptom burden of patients in the past week and has been validated in Chinese . The severity of depression and generalized anxiety were assessed using the 9-item depression scale PHQ-9 and the 7-item GAD-7, respectively. PHQ-9 and GAD-7 are validated and reliable in their Chinese versions [17-19]. Illness anxiety was evaluated using the 7-item WI-7 Chinese version . Population-level and clinical practice health and disability were assessed using the WHO-DAS 2.0, Chinese version . Patients’ perception of their symptom-related thoughts, feelings, and behaviors was assessed using the SSD-12, which was developed based on the DSM-5 criteria . The SF-12 captures information on health-related quality of life (QoL) and was validated in Chinese [23, 24].
For our research purpose, the “Somatic Symptom Disorders and Related Disorders” module of SCID-5-RV was purchased. The nine participating centers, all of which being authoritative centers in the field of psychiatry in China, cooperated to translate the SCID-5-RV into Chinese, to translate it back into English again, and to compare it with the initial English version, finally confirming that the translation was accurate . A final version was accepted and agreed upon by all Chinese researchers after translations were discussed. The Chinese translation did not get the APA’s sanction; therefore, the present study is a preliminary study that establishes the basis for a future Chinese version.
All patients underwent an interview (SCID-5-RV)following the criteria of DSM-5 for SSD. All the research assistants (psychiatrists and postgraduate medical students in psychiatry) were trained with the SCID-5-RV interview. The assistants worked under the direct supervision of attending psychiatrists with >3 years of experience (i.e., the clinical heads of psychosomatic medicine.
The self-evaluation of treatment satisfaction and efficacy were divided into six grades (0-5 points): 0 means "not satisfied with the treatment in the past 6 months at all " or" considered that the treatment in the past 6 months was completely failed"; and 5 means "very satisfied with the treatment in the past 6 months" or "considered that the treatment in the past 6 months was very successful".
Based on the results of the SCID-5-RV, the patients could be diagnosed with SSD in the presence of criteria A and B . Patients with one B criterion were classified as mild SSD, those with at least two B criteria were classified as moderate SSD, and those with at least two B criteria and the C criterion were classified as SSD.
The results of the SCID-5-RV were compared with the results of the other scales. The combination of the PHQ-15 and SSD-12 is considered diagnostic for SSD .
All data were stored at the University Medical Centre Freiburg. The same center was responsible for monitoring the project sites and for data analysis. The study was approved by the ethics committees of all participating centers. The approval number at the University Medical Centre Freiburg was S-K276. The data were collected by research assistants between May 2016 and Marc, 2017.
All statistical analyses were performed using SPSS 22.0 (IBM, Armonk, NY, USA). Categorical variables were described as numbers and percentages and analyzed using the chi-square test. Continuous variables were presented as means and standard deviations and analyzed using the Student t-test for two independent groups. One-way analysis of variance and the LSD post hoc test were used for the comparison of continuous variables among multiple groups. The Spearman correlation was used to analyze the relationship between SCID-5-RV and the other scales. Two-tailed P-values <0.05 were considered significant. Alpha-inflation might be an issue, and to mitigate it, only P-values <0.001 were considered as being high-impact differences or correlations.