To develop and validate a new self-report questionnaire for the assessment of the psychological features of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition somatic symptom disorder.
The Somatic Symptom Disorder–B Criteria Scale (SSD-12) was developed in several steps from an initial pool of 98 items. The SSD-12 is composed of 12 items; each of the three psychological subcriteria is measured by four items. In a cross-sectional study, the SSD-12 was administered to 698 patients (65.8% female, mean [standard deviation] age = 38.79 [14.15] years) from a psychosomatic outpatient clinic. Item and scale characteristics as well as measures of reliability and validity were determined.
The SSD-12 has good item characteristics and excellent reliability (Cronbach α = .95). Confirmatory factor analyses suggested that a three-factorial structure that reflects the three psychological criteria interpreted as cognitive, affective, and behavioral aspects (n = 663, Comparative Fit Index > 0.99, Tucker-Lewis Index > 0.99, Root Mean Square Error of Approximation = 0.06, 90% confidence interval = 0.01-0.08). SSD-12 total sum score was significantly associated with somatic symptom burden (r = 0.47, p < .001) and health anxiety (r = 0.71, p < .001), and moderately associated with general anxiety (r = 0.35, p < .001) and depressive symptoms (r = 0.22, p < .001). Patients with a higher SSD-12 psychological symptom burden reported higher general physical and mental health impairment and significantly higher health care use.
The SSD-12 is the first self-report questionnaire that operationalizes the new psychological characteristics of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition somatic symptom disorder. Initial assessment indicates that the SSD-12 has sufficient reliability and validity to warrant further testing in both research and clinical settings.
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From the Department of Psychosomatic Medicine and Psychotherapy (Toussaint, Murray, Voigt, Herzog, Gierk, Löwe), University Medical Center Hamburg-Eppendorf & Schön Clinic Hamburg-Eilbek, Hamburg, Germany; VA HSR&D Center for Health Information and Communication (Kroenke), Indiana University School of Medicine, and Regenstrief Institute, Indianapolis, Indiana; Department of Clinical Psychology (Rief), University of Marburg, Marburg, Germany; and Department of Psychosomatic Medicine and Psychotherapy (Henningsen), Technical University of Munich, Munich, Germany.
Address correspondence and reprint requests to Anne Toussaint, PhD, Department of Psychosomatic Medicine and Psychotherapy, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany. E-mail: firstname.lastname@example.org
Received for publication February 10, 2015; revision received July 31, 2015.