The relationship of impairment to personality disorder severity among individuals with specific axis I disorders: results from the National Epidemiologic Survey on Alcohol and Related Conditions.

The present study examined one dimensional approach to personality disorders (PDs) in a large (n = 43,093), nationally representative sample of the U.S. population. Respondents were classified in four personality severity categories (no PD, subthreshold PD, simple PD, complex PD). Linear regression analyses were conducted to examine mental disability by PD severity for major DSM-IV substance use, mood and anxiety disorders. Significant increases in disability were observed between no PD and simple PD and between simple PD and complex PD for each Axis I disorder except drug dependence, but few differences in disability were found between no PD and subthreshold PD. This study found support for the clinical utility of the dimensional classification of PD severity with regard to the distinction between simple and complex PD and for a combined no PD-subthreshold PD level of severity. Future planned analyses will address the clinical utility of the classification prospectively, with a full battery of all Axis II PDs.