Toward empirically based criteria for the classification of somatoform disorders

There is a major need for an empirical evaluation of classification criteri a for somatoform dis orders. The present study analyzes psychometric proper ties of the existing criteria for somatization disorder. The full sample co nsisted of 324 patients seeking help because of "psychosomatic problems." D ata from a subsample of carefully diagnosed patients with somatization synd rome (n = 76) and a clinical comparison group (n = 32) permitted the analys is of the discriminative power of items. Twenty-one somatic symptoms adopte d from DSM-IV and ICD-10 criteria did not exhibit the necessary psychometri c characteristics (item probability, item-total correlation, etc.). Thirty- two somatic symptoms showed a satisfactory psychometric performance. A cut- off of seven or more symptoms yielded the best discrimination between low a nd high disability. New criteria for somatization syndrome ("polysymptomati c somatoform disorder") are proposed taking into account for the strong ass ociation of somatization and abnormal illness behavior. (C) 1999 Elsevier S cience Inc.