Examining the reliability and validity of the ICD-11 personality disorder severity diagnosis

The International Classification of Diseases, 11th edition includes a new personality disorder diagnosis, in light of growing concerns of the categorical personality disorder diagnoses. The purpose of the current study was to examine the reliability and validity of the severity dimension of the new International Classification of Diseases, 11th edition diagnosis, through multi-method assessment.

In a community mental health sample (n = 311), we examined the interrater reliability of the severity diagnosis and evaluated the diagnosis against self-report measures of dimensional personality pathology and psychopathology constructs and traditional categorical and informant-report measures.

Intraclass correlations indicated 'excellent' reliability of the diagnostic ratings. Large associations were observed between the International Classification of Diseases, 11th edition clinician diagnosis and overall impairment measures. Generally, the International Classification of Diseases, 11th edition clinician diagnosis exhibited largest associations with measures of internalising dysfunction, and more variable associations with interpersonal and externalising impairment. The International Classification of Diseases, 11th edition clinician diagnosis showed a large association with borderline personality disorder symptom scores and moderate associations with Paranoid, Schizoid and Avoidant personality disorder scores. Similar patterns emerged of the associations between the International Classification of Diseases, 11th edition personality disorder diagnosis with self-report and informant-report measures, although the associations were larger with self-report measures.

These findings provide promising initial evidence for the reliability and validity of the new International Classification of Diseases, 11th edition personality disorder diagnosis, indicating that the new conceptualisation of personality disorders may address issues within the categorical model.