Towards positive diagnostic criteria: a systematic review of somatoform disorder diagnoses and suggestions for future classification.

OBJECTIVES: The classification of somatoform disorders is currently being revised in order to improve its validity for the DSM-V and ICD-11. In this article, we compare the validity and clinical utility of current and several new diagnostic proposals of those somatoform disorders that focus on medically unexplained somatic symptoms.

METHODS: We searched the Medline, PsycInfo, and Cochrane databases, as well as relevant reference lists. We included review papers and original articles on the subject of somatoform classification in general, subtypes of validity of the diagnoses, or single diagnostic criteria.

RESULTS: Of all diagnostic proposals, only complex somatic symptom disorder and the Conceptual Issues in Somatoform and Similar Disorders (CISSD) example criteria reflect all dimensions of current biopsychosocial models of somatization (construct validity) and go beyond somatic symptom counts by including psychological and behavioral symptoms that are specific to somatization (descriptive validity). Predictive validity of most of the diagnostic proposals has not yet been investigated. However, the number of somatic symptoms has been found to be a strong predictor of disability. Some evidence indicates that psychological symptoms can predict disease course and treatment outcome (e.g., therapeutic modification of catastrophizing is associated with positive outcome). Lengthy symptom lists, the requirement of lifetime symptom report (as in abridged somatization), complicated symptom patterns (as in current somatization disorder), and imprecise definitions of diagnostic procedures (e.g., missing symptom threshold in complex somatic symptom disorder) reduce clinical utility.

CONCLUSION: Results from the reviewed studies suggest that, of all current and new diagnostic suggestions, complex somatic symptom disorder and the CISSD definition appear to have advantages regarding validity and clinical utility. The integration of psychological and behavioral criteria could enhance construct and descriptive validity, and confers prospectively relevant treatment implications. The incorporation of a dimensional approach that reflects both somatic and psychological symptom severity also has the potential to improve predictive validity and clinical utility.