Inventory of Interpersonal Problems Personality Disorder scales: operating characteristics and confirmatory factor analysis in nonclinical samples

Research involving clinical samples has demonstrated the utility of a 28-item personality disorder (PD) screening measure (Inventory of Interpersonal Problems--Personality Disorder scale [IIP-PD]) culled from the IIP in the prediction of the presence or absence of a PD (Pilkonis, Kim, Proietti, & Barkham, 1996). This article extends these diagnostic efficiency findings to nonclinical samples and presents additional data regarding the factor structure of the 28 IIP-PD items. Diagnostic efficiency statistics for the IIP-PD scale, calculated using both interview and self-report methods, support the utility of the IIP-PD scale as a screening tool for the presence or absence of a PD. High specificity estimates indicate that individuals who do not exceed Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) symptom thresholds rarely exceed the IIP-PD cutoff. Furthermore, a high negative predictive power (NPP) estimate derived using an interview-based diagnostic standard suggests that the IIP-PD scale accurately screens out individuals who do not have a PD. Finally, cross-validated confirmatory factor-analytic results involving items composing the 5 IIP PD subscales identified in previous research (Kim, Pilkonis, & Barkham, 1997) suggest that a measurement model with a single second-order factor (general PD) and 5 first-order factors (one representing each PD subscale) provided the best fit to the observed data compared to 2 other competing models.