Predictive validity and clinical utility of DSM-5 Somatic Symptom Disorder--comparison with DSM-IV somatoform disorders and additional criteria for consideration.

OBJECTIVE: Major changes to the diagnostic category of somatoform disorders are being proposed for DSM-5. The effect of e.g. the inclusion of psychological criteria (criterion B) on prevalence, predictive validity, and clinical utility of "Somatic Symptom Disorder" (SSD) remains unclear. A prospective study was conducted to compare current and new diagnostic approaches.
METHODS: In a sample of N=456 psychosomatic inpatients (61% female, mean age=44.8±10.4 years) diagnosed with somatoform, depressive and anxiety disorders, we investigated the current DSM-5 proposal (SSD) plus potential psychological criteria, somatic symptom severity, and health-related quality of life at admission and discharge.
RESULTS: N=259 patients were diagnosed with DSM-IV somatoform disorder (56.8%). With a threshold of 6 on the Whiteley Index to assess psychological criteria, the diagnosis of SSD was similarly frequent (51.8%, N=230). However, SSD was a more frequent diagnosis when we employed the recommended threshold of one subcriterion of criterion B. Patients diagnosed with only SSD but not with DSM-IV somatoform disorder showed greater psychological impairment. Both diagnoses similarly predicted physical functioning at discharge. Bodily weakness and somatic and psychological attributions at admission were among significant predictors of physical functioning at discharge. Reduction of health anxiety, bodily weakness, and body scanning significantly predicted an improvement of physical functioning.
CONCLUSIONS: Psychological symptoms enhance predictive validity and clinical utility of DSM-5 Somatic Symptom Disorder compared to DSM-IV somatoform disorders. The SSD diagnosis identifies more psychologically impaired patients than its DSM-IV precursor. The currently suggested diagnostic threshold for criterion B might increase the disorder's prevalence.