The IPDE was developed within the Joint Program for the Diagnosis and Classification of Mental Disorders of the World Health Organization (WHO) and U.S. National Institutes of Health (NIH) and provides a uniform approach for assessing personality disorders for both the DSM-IV^TM and the ICD-10 classification systems. The interview is the most widely used of its kind and is the only personality disorder interview based on worldwide field trials. The IPDE Manual contains the interview questions to assess either the 11 DSM-IV or the 10 ICD-10 personality disorders. The two IPDE modules (DSM-IV and ICD-10) contain both a self-administered screening questionnaire and a semistructured interview booklet with scoring materials.

The IPDE Screening Questionnaire is a self-administered carbonless form that contains 77 DSM-IV or 59 ICD-10 items written at a 4th-grade reading level. The patient responds either True or False to each item and can complete the questionnaire in 15 minutes or less. The clinician can quickly score the questionnaire and identify those patients whose scores suggest the presence of a personality disorder. Then the IPDE clinical interview can be administered.

Results from the IPDE Interview allow the examiner to assign a definite, probable, or negative diagnosis for each personality disorder. The IPDE Interview questions are arranged in a format that provides the optimal balance between a spontaneous, natural clinical interview and the requirements of standardization and objectivity. The questions are arranged in sections (e.g., Background Information, Work, Self, Interpersonal Relationships) with open-ended inquiries provided at the beginning of each section to enable a smooth transition from the previous section. For each IPDE Interview question, the corresponding personality disorder and the specific diagnostic criterion is identified with precise scoring guidelines. Also at least one criterion must have been present prior to age 25 years before that particular personality disorder can be diagnosed. The clinician records the scores for each response on the appropriate IPDE Answer Sheet.

After the interview, the clinician transcribes the scores from the IPDE Answer Sheet to the appropriate Scoring Booklet. The 12-page Scoring Booklet contains a scoring page for each personality disorder. The cover page contains the personality disorder summary table with a confidence rating and diagnosis listed for each personality disorder and the Dimensional score profile. Dimensional scales provide scores on the traits underlying each of the categorical personality disorders, regardless of whether or not the patient has the disorder.

The IPDE has proven to be a user-friendly and clinically meaningful tool for clinicians throughout the international psychiatric community. It has demonstrated interrater reliability and temporal stability that is roughly similar to instruments used to diagnose psychoses, mood, anxiety, and substance use disorders.