Further evidence for a broader concept of somatization disorder using the somatic symptom index.

Somatization syndromes were defined in a sample of 102 psychosomatic inpatients according to the restrictive criteria of DSM-III-R somatization disorder and the broader diagnostic concept of the Somatic Symptom Index (SSI). Both groups showed a qualitatively similar pattern of psychopathological comorbidity and had elevated scores on measures of depression, hypochondriasis, and anxiety. A good discrimination between mild and severe forms of somatization was found by using the SSI criterion. SSI use accounted for a substantial amount of comorbidity variance, with rates of 15%-20% for depression, 16% for hypochondriasis, and 13% for anxiety. The results provide further evidence for the validity of the SSI concept, which reflects the clinical relevance of somatization in addition to the narrow definition of somatization disorder.