The Relationship of Hypochondriasis to Anxiety, Depressive, and Somatoform Disorders.

BACKGROUND: Though the phenotype of anxiety about medical illness has long been recognized, there continues to be debate as to whether it is a distinct psychiatric disorder and, if so, to which diagnostic category it belongs. OBJECTIVE: Our objective was to investigate the pattern of psychiatric comorbidity in hypochondriasis (HC) and to assess the relationship of health anxiety to anxiety, depressive, and somatoform disorders. METHODS: Data were collected as part of a clinical trial on treatment methods for HC. In all, 194 participants meeting criteria for Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) HC were assessed by sociodemographic variables, results of structured diagnostic interviews, and validated instruments for assessing various symptom dimensions of psychopathology. RESULTS: Most of the individuals with HC had comorbid psychiatric illness; the mean number of comorbid diagnoses was 1.4, and 35.1% had HC as their only diagnosis. Participants were more likely to have only comorbid anxiety disorders than only comorbid depressive or somatoform disorders. Multiple regression analysis of continuous measures of symptoms revealed the strongest correlation of health anxiety with anxiety symptoms, and a weaker correlation with somatoform symptoms; in multiple regression analysis, there was no correlation between health anxiety and depressive symptoms. CONCLUSION: Our findings suggest that the entity of health anxiety (HC in DSM-IV and illness anxiety disorder in DSM-5) is a clinical syndrome distinct from other psychiatric disorders. Analysis of comorbidity patterns and continuous measures of symptoms suggest that its appropriate classification is with anxiety rather than somatoform or mood disorders.