Does DSM-IV Already Capture the Dimensional Nature of Personality Disorders?

Objective: Personality disorder research favors a dimensional representation of the personality disorders over categorical classification, and this is one of the central justifications for changing the diagnostic approach in DSM-5. However, recent research has suggested that the most important loss of information in a categorical system is the failure to account for subthreshold levels of pathology. DSM-IV can be considered to already accommodate a quasi-dimensional system insofar as individuals who do not meet the threshold for diagnosis can be noted to have traits of the disorder. In the present report, we examined 2 questions related to dimensional scoring of the personality disorders and the association between personality pathology and psychosocial morbidity: (1) Is the DSM-IV 3-point dimensional convention (absent, subthreshold traits, present) more strongly associated with indicators of psychosocial morbidity than a categorical approach toward diagnosis? and (2) How does the 3-point dimensional scoring convention compare to the 5-point system proposed for DSM-5 and to a criterion count approach in which the dimensional score represents the sum of the number of criteria present?

Method: From September 1997 to June 2008, 2,150 psychiatric outpatients were evaluated with semistructured diagnostic interviews for DSM-IV Axis I and Axis II disorders and measures of psychosocial morbidity.

Results: The DSM-IV 3-point dimensional convention was more strongly associated with measures of psychosocial morbidity than was categorical diagnosis. There was no difference between the 3-point, 5-point, and criterion count methods of scoring the DSM-IV personality disorder dimensions.

Conclusions: Dimensional scoring of the DSM-IV personality disorders was more highly correlated with measures of psychosocial morbidity than was categorical classification. The DSM-IV 3-point rating convention was as valid as scoring methods using more finely graded levels of severity. These findings argue against changing the current DSM-IV diagnostic approach and instead advocate for the increased recognition that DSM-IV already includes a valid dimensional rating.

J Clin Psychiatry

© Copyright 2011 Physicians Postgraduate Press, Inc.

Submitted: February 28, 2011; accepted June 23, 2011.

Online ahead of print: August 23, 2011 (doi:10.4088/JCP.11m06974).

Corresponding author: Mark Zimmerman, MD, Bayside Medical Center, 235 Plain St, Providence, RI 02905 (mzimmerman@lifespan.org).