Psychological and interactional characteristics of patients with somatoform disorders: Validation of the Somatic Symptoms Experiences Questionnaire (SSEQ) in a clinical psychosomatic population.

OBJECTIVE The new DSM-5 Somatic Symptom Disorder (SSD) emphasizes the importance of psychological processes related to somatic symptoms in patients with somatoform disorders. To address this, the Somatic Symptoms Experiences Questionnaire (SSEQ), the first self-report scale that assesses a broad range of psychological and interactional characteristics relevant to patients with a somatoform disorder or SSD, was developed. This prospective study was conducted to validate the SSEQ. METHODS The 15-item SSEQ was administered along with a battery of self-report questionnaires to psychosomatic inpatients. Patients were assessed with the Structured Clinical Interview for DSM-IV to confirm a somatoform, depressive, or anxiety disorder. Confirmatory factor analyses, tests of internal consistency and tests of validity were performed. RESULTS Patients (n=262) with a mean age of 43.4 years, 60.3% women, were included in the analyses. The previously observed four-factor model was replicated and internal consistency was good (Cronbach's α=.90). Patients with a somatoform disorder had significantly higher scores on the SSEQ (t=4.24, p<.001) than patients with a depressive/anxiety disorder. Construct validity was shown by high correlations with other instruments measuring related constructs. Hierarchical multiple regression analyses showed that the questionnaire predicted health-related quality of life. Sensitivity to change was shown by significantly higher effect sizes of the SSEQ change scores for improved patients than for patients without improvement. CONCLUSION The SSEQ appears to be a reliable, valid, and efficient instrument to assess a broad range of psychological and interactional features related to the experience of somatic symptoms.