Clinical cut-off point for the Distrust dimension of the Dimensional Clinical Personality Inventory 2 (IDCP-2)

The Clinical Dimensional Personality Inventory 2 (IDCP-2) is a 206-item self-report tool developed for the assessment of 12 dimensions (divided into 47 factors) of personality pathology. One of the scales comprising the instrument, the Distrust scale, is intended to provide psychometric information on traits closely related to the Paranoid Personality Disorder (PPD). In the present research, we used the Item Response Theory and the Receiver Operating Characteristic curve analysis to establish a clinical meaningful cutoff for the Distrust scale. Participants were 1,679 adults, among outpatients diagnosed with PPD, outpatients diagnosed with other PDs, and adults from the community. The Wright map revealed that outpatients were located at the very high levels on the latent continuum of the Distrust scale, with a very large effect size for the mean difference between patients and non-patients. The ROC curve supported a cutoff at -1.00 score in theta standardization which yielded 0.87 of sensitivity and 0.54 of specificity. Findings from the present investigation suggest the IDCP-2 Distrust scale is useful as a screening tool of the core features of the PPD. We address potential clinical applications for the instrument and discuss limitations from the present study.