Convergent and incremental predictive validity of clinician, self-report, and structured interview diagnoses for...

Research has demonstrated poor agreement between clinician-assigned personality disorder (PD) diagnoses and those generated by self-report questionnaires and semistructured diagnostic interviews. No research has compared prospectively the predictive validity of these methods. We investigated the convergence of these 3 diagnostic methods and tested their relative and incremental validity in predicting independent, multimethod assessments of psychosocial functioning performed prospectively over 5 years.

Participants were 320 patients in the Collaborative Longitudinal Personality Disorders Study diagnosed with PDs by therapist, self-report, and semistructured interview at baseline. We examined the relative incremental validity of therapists' naturalistic ratings relative to these other diagnostic methods for predicting psychosocial functioning at 5-year follow-up.

Hierarchical linear regression analyses revealed that both the self-report questionnaire and semistructured interview PD diagnoses had significant incremental predictive validity over the PD diagnoses assigned by a treating clinician. Although, in some cases, the clinicians' ratings for individual PDs did have validity for predicting subsequent functioning, they did not generally provide incremental prediction beyond the other methods. These findings remained robust in a series of analyses restricted to a subsample of therapist ratings based on clinical contact of 1 year or greater.

These results from a large clinical sample echo previous research documenting limited agreement between clinicians' naturalistic PD diagnoses and those from self-report and semistructured interview methods. They extend prior work by providing the first evidence about the relative predictive validity of these different methods. Our findings challenge the validity of naturalistic PD diagnoses and suggest the use of structured diagnostic instruments.