\ Reliability and validity of Turkish Form of Somatic Symptom Scale and Level 2 Somatic Symptom Scale

This study is to demonstrate the reliability and validity of the Turkish form of Somatic Symptom Scale and Level 2 Somatic Symptom Scale developed according to DSM-5 criteria. Methods: This study was carried out with patients with a diagnosis of any somatic symptom disorder according to DSM-5 criteria who are under treatment in Celal Bayar University Faculty of Medicine Psychiatry Inpatient or Outpatient Clinics. Patients with any mental disease according to DSM-5 criteria except for somatic symptom disorders and patients who have physical or neurological disease requiring continuous treatment were excluded. Accordingly, 31 patient with somatic symptom disorder, 16 patients with illness anxiety disorder and three patients with conversion disorder were included. As the healthy control group 100 volunteers without any mental or physical disease were included. Beside Somatic Symptom Scale and Level 2 Somatic Symptom Scale, the most widely used self-rated scale, Health Anxiety Inven-tory (HAI) was used for concurrent validity. In reliability analysis internal consistency coefficient and item-total correlation analysis; in validity analyses factor analysis and correlation analysis with the Pearson Correlation Analysis (PCA) was performed. ROC analysis was conducted to determine sensitivity and specificity of the scale and area under the curve above 0.90 is considered as statistically significant. Results: The mean age of the study group was 29.0 +/- 11.9 years and 61.3% of the sample group (n= 92) were female. 63.3% of the group were college graduates, 19.3% primary school graduates, 10.7% is also high school graduates. Disease duration of patient group was 17.4 +/- 11.8 years. The internal consistency of the Level 2 Somatic Symptom Scale was 0.83 and, item-total correlation coefficients of the Level 2 Somatic Symptom Scale were between 0.26 and 0.62. The internal consistency of the Somatic Symptom Scale was 0.96 and, item-total correlation coefficients of the Somatic Symptom Scale were between 0.89 and 0.92. In the exploratory factor analysis of Level 2 Somatic Symptom Scale, single-factor solution was obtained and the eigenvalue was 4.67, explaining 31.16% of the total variance. Factor loadings of the items were between 0.41 and 0.78. Coefficient of correlation analysis with HAI was calculated as r=0.59. Coefficient of correlation analysis of Somatic Symptom Scale with HAI was calculated as r=0.83. According to ROC analysis, the area under the curve was found as 0.92 for Level 2 Somatic Symptom Scale, and 0.98 for Somatic Symptom Scale. Conclusion: These findings have been shown that the Somatic Symptom Scale and Level 2 Somatic Symptom Scale are reliable and valid for Turkish.