Comorbidity of anxiety disorders and hypochondriasis considering different diagnostic systems.

The influence of different hierarchical guidelines in various classification systems on the diagnosis of anxiety disorders and hypochondriasis was investigated. Using a semistructured polydiagnostic interview (including DSM-III, DSM-III-R, and the 1987 draft version of ICD-10), lifetime diagnoses were determined in B2 outpatients with a DSM-III-R anxiety disorder. In all diagnostic systems, half of our patients exhibited the descriptive features of hypochondriasis. As demonstrated, the formulation of restrictive hierarchical rules--as in DSM-III--contributes to the concept of "primary" hypochondriasis, while secondary hypochondriasis remains underdiagnosed. Concordance rates for hypochondriasis were high between DSM-III-R and ICD-10, but not with DSM-III. Although hypochondriasis showed a strong association with the clinical course of panic disorder (PD), it could not be explained as a consequence of greater illness severity of PD with agoraphobia (AP). Our data underline the conceptualization of hypochondriasis as a phenomenologically homogeneous diagnostic category that may be differentiated from comorbid psychiatric conditions.