Clinical validity of the "Dimensional Assessment of Personality Pathology (DAPP)" for psychiatric patients with and without a personality disorder diagnosis.

There is a movement towards a dimensional classification of personality disorders (PD). However, data linking dimensional systems and the categorical system for classifying PD are lacking. In the present study, N = 165 normal subjects and N = 222 nonpsychotic in-patients (including N = 81 patients with a PD diagnosis) completed the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ) measuring 18 PD traits. DSM-IV PD symptoms were assessed by SCID-II interviews. Group differences were analyzed by ANCOVA, and the relation between the dimensional and categorical approach was investigated by regression, ROC, and MDS analyses. Patients with PD exhibited elevated scores on all DAPP traits compared with controls. Patients without PD scored in between. Each DSM-IV PD could be described by a distinct profile of DAPP traits. Results support the assumption that the DAPP trait system can represent mean differences between clinically defined subgroups. The categorical system can be mapped onto the dimensional DAPP system with sufficient clinical specificity.