MCMI-II diagnosis of borderline personality disorder: base rates versus prototypic items.

The Millon Clinical Multiaxial Inventory-II (MCMI-II) profiles of 26 psychiatric inpatients diagnosed as having borderline personality disorders were compared with profiles of 42 patients with no personality disorders. The borderline group scored significantly higher on the following scales: Disclosure (X), Debasement (Z), Passive-Aggressive (8A), Self-Defeating (8B), Borderline (C), and Major Depression (CC). Differences approaching significance were also found on substance abuse measures: the Alcohol Dependence (B) scale and Drug Dependence (T) scale. These findings are consistent with criteria established in the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev. DSM-III-R]; American Psychiatric Association, 1987) and the results of other studies utilizing the MCMI-II. In addition, diagnostic efficiency of Scale C was assessed at various cutoff points defined by either base rate (BR) scores or the number of prototypic items endorsed. The greatest efficiency was found when a cutoff of seven or more prototypic items was utilized, with nearly 80% of the patients correctly classified. Results are discussed in terms of their relevance for further research.