Utility and Optimal Cut-off point of the Somatic Symptom Scale-8 in severe Somatic Symptoms and Related Disorders with Central Sensitization Syndrome

Abstract

Abstract Background In central sensitization syndrome (CSS), functional physical symptoms are severe due to central sensitization. The Somatic Symptom Scale-8 (SSS-8) is a simple tool to assess medical conditions with somatic symptoms and related disorders, but the cut-off point to identify severe cases of comorbid CSS is unknown. This study aimed to determine the SSS-8 score cut-off point for discriminating severe somatic symptoms and related conditions. Methods In total, 143 patients with somatic symptoms and related disorders attending outpatient clinics of a university hospital in Japan were included in the study. The participants were evaluated using the SSS-8 for somatic symptoms, Hospital Anxiety and Depression Scale (HADS) for anxiety and depressive symptoms, Pain Catastrophizing Scale (PCS) for catastrophic thoughts, and Central Sensitization Inventory (CSI-A, B) for CSS. Receiver operating characteristic (ROC) curve analysis was performed using the propensity score. The area under the curve (AUC) was calculated using a propensity score considering PCS, age, sex, HADS, and CSI-B as confounders of SSS-8 and CSS to evaluate differences in diagnostic accuracy between patients with and without SSS-8. The sensitivity and specificity of the ROC analysis were then used to determine the cut-off point for discriminating severe cases of SSS-8. Results Of the 143 participants, 126 responded (51 in the CSS group and 75 in the non-CSS group), with a valid response rate of 88.1 percent. In the ROC analysis, the propensity score including SSS-8 was statistically more accurate. The optimal SSS-8 score for discriminating severe cases of somatic symptoms and related disorders was at 13 points, with an AUC of 0.88, sensitivity of 84.3 percent, and specificity of 77.3 percent. Conclusions The SSS-8 is a useful tool for discriminating severe cases of somatic symptomatology and related disorders comorbid with CSS.