Instrument to assess depersonalization-derealization in panic disorder.

There is a long history of scholarly interest on depersonalization-derealization (DD) and its role in clinical anxiety, but there is a paucity of appropriate assessment instruments available. Our objective was to develop and evaluate a self-report measure of DD for use with clinically anxious patients. Panic disorder patients (n=169) were surveyed about DD experiences and provided data on a new item pool for psychometric development. DD episodes were common and a 28-item Depersonalization-Derealization Inventory was found to possess good reliability and validity. DD appears to be prevalent and clinically relevant in panic disorder. Continued study of DD is warranted and may be facilitated by the availability of a suitable instrument with promising psychometric properties. A 12-item version of the instrument may be appropriate as a brief screen. Copyright 2002 Wiley-Liss, Inc.