Objective: Comorbidity among personality disorders is widely considered problematic. The validity of one proposed solution, diagnostic hierarchies, was investigated in the current study with respect to borderline, schizotypal, avoidant, and obsessive–compulsive personality disorders.
Method: One approach used discriminant functions, derived from multiple psycho-social domains, that were used to classify comorbid individuals from the Collaborative Longitudinal Personality Disorder study (CLPS) to explore the possibility of hierarchical precedence of one personality disorder over another. A second approach examined the incremental increase in R2-value in predicting functioning and personality provided by each diagnosis over each other diagnosis.
Results: Obsessive–compulsive personality disorder was consistently subordinate to other diagnoses, whereas other indications of hierarchical relationships were domain-specific.
Conclusion: Results indicate minimal support for an over-arching hierarchical pattern among studied personality disorders, and suggest the inclusion of all relevant diagnoses in clinical practice.