Somatoform's placement and validity in the hierarchical taxonomy of psychopathology (HiTOP).

Limitations of a polythetic-categorical classification system has sparked ongoing quantitative efforts to establish a valid and reliable method for diagnosing mental illness. Dimensional methods of classification, such as the Hierarchical Taxonomy of Psychopathology (HiTOP), have been found to ameliorate the limitations of a categorical approach - despite the provisional placement of a Somatoform spectrum. The current investigation sought to elucidate the placement of the Somatoform spectrum within the HiTOP model, and to further corroborate discriminant and convergent validity of the Somatoform spectrum. Using a sample of patients seeking chronic low-back pain treatment (n = 200), superior model fit suggested Somatoform fits better as a separate spectrum from Internalizing and placing Somatoform as a subfactor of Internalizing did not improve model fit. Discriminant and convergent validity with an external criteria demonstrated distinctiveness of the Somatoform spectrum from the Internalizing spectrum in the HiTOP model.