The findings lend support to the new "hybrid" model, which combines the "core" dimensions of personality disorder with various maladaptive personality traits found in individual patients, according to the report by Leslie C. Morey, PhD, of Texas A & M University and Andrew E. Skodol, MD, of the University of Arizona College of Medicine and Columbia University College of Physicians and Surgeons.
Hybrid Model Compares Well with DSM-IV Diagnosis of Personality Disorders
Experts working on the long-awaited DSM-5—to be published later this month—recommended substantial revisions to the section on personality disorders. Specifically, they proposed a "hybrid categorical-dimensional model" including not only "core impairments in personality functioning" but also various combinations of "pathological personality traits" associated with these conditions. Goals of the proposal included:
- Reducing overlap among personality disorder diagnoses
- Reducing heterogeneity among patients receiving the same diagnosis
- Eliminating arbitrary diagnostic thresholds with little or no research basis
- Addressing the widespread use of the vague "personality disorder not otherwise specified" diagnosis
- Providing diagnostic thresholds that are related to level of impairment in a meaningful way
Although the proposal was endorsed by the DSM-5 Task Force, it was decided that the hybrid model required more research support before being fully adopted. Therefore, the hybrid model will be referred to as an "alternative model" and placed in Section III of the DSM-5, which contains concepts for which further research is needed. Meanwhile, the main body of the DSM-5 will retain the DSM-IV criteria for personality disorders.
A key concern was whether the new model would lead to discrepancies between DSM-IV and DSM-5 definitions of the same disorder—especially for diagnoses such as borderline, antisocial, and schizotypal personality disorders for which a substantial body of research literature exists. "It is important to evaluate whether thresholds can be established that provide solid continuity between DSM-IV and proposed DSM-5 definitions," Drs Morey and Skodol write.
Their study included a national sample of 337 patients, who were diagnosed under both systems by clinicians familiar with their cases. The results showed appreciable correspondence between the DSM-IV diagnosis of personality disorders and the hybrid categorical-dimensional diagnostic model proposed for DSM-5. The two models agreed well for various subtypes, including borderline, avoidant, obsessive-compulsive, antisocial, narcissistic, and schizotypal personality disorders.
"[T]raditional DSM-IV categories of personality disorder can be rendered in terms of core impairments in personality functioning and pathological personality traits with high fidelity," Drs Morey and Skodol conclude. They believe their findings "should allay fears that translating PDs into personality functioning and trait terms will be disruptive to clinical practice or research."
The researchers add, "[T]he definition of all personality disorders in terms of core impairments in personality functioning and pathological personality traits identifies personality pathology with high sensitivity and specificity and utility for treatment planning and prognosis." If their results are borne out by future studies using other methods and samples, Drs Morey and Skodol believe their findings support adopting the new categorical-dimensional model for clinical diagnosis.