The Shedler-Westen Assessment Procedure-200 as a basis for modifying DSM personality disorder categories

The Shedler-Westen Assessment Procedure-200 (SWAP) is a Q-sort instrument designed to assess personality pathology on the basis of clinician ratings. On the basis of research with the SWAP, its creators have proposed a group of 12 personality disorder (PD) diagnoses that can be used to replace or modify current Axis II categories of the Diagnostic and Statistical Manual of Mental Disorders (DSM). The authors discuss conceptual and empirical issues that require clarification before this proposal can be properly evaluated. They identify problematic psychometric features of the SWAP, including its unrepresentative normative sample, its reliance on a fixed skewed distribution, and anomalies in its T-score approach to diagnoses. In addition, a review of research on SWAP-based PD categories indicates that important information regarding diagnostic coverage, validity, and temporal stability is presently lacking. The authors conclude that research evidence is currently insufficient to justify the use of SWAP-based PD categories to guide revision of the DSM.