External Validity of Two Personality Disorder Inventories

The external validity of two self-report measures of personality disorders, the Personality Diagnostic Questionnaire—Revised (PDQ-R—: Hyler & Rieder, 1987) and the MMPI-Personality Disorder scales (MMPI—PD—Morey, Waugh, & Blashfield, 1985), was assessed by comparing the dimensional scores and diagnoses derived from these inventories to those from an Axis II interview (the Structured Interview for DSM-III-R Personality—SIDP-R; Pfohl, Blum, Zimmerman, & Stangl, 1989) in a sample of 57 outpatients. Results indicated that the PDQ-R and MMPI-PD dimensional scores were significantly correlated with the corresponding scores from the SIDP-R. However, diagnostic agreement between the self-report inventories and the structured interview was poor. Therefore, results suggest that self-report Axis II diagnoses should not be used as a substitute for diagnoses derived from a structured interview. The ability of these inventories to rule out Axis II diagnoses indicates that they may be useful screening measures.