Validating the German version of the Personality Disorder Severity-ICD-11 Scale using nominal response models

Area of Science:

• Psychiatry and Psychology
• Mental Health Assessment
• Psychometric Validation

Background:

• The International Classification of Diseases-11 (ICD-11) introduced a new personality disorder (PD) classification focused on severity.
• Existing self-report measures for PD severity are numerous, but only the Personality Disorder Severity-ICD-11 (PDS-ICD-11) aligns with ICD-11 operationalization.
• Prior research suggested the PDS-ICD-11 measures a unidimensional construct, but scoring assumptions for bipolar items required further examination.

Purpose of the Study:

• To investigate the latent structure of the German version of the PDS-ICD-11.
• To test the assumptions underlying the scoring of the PDS-ICD-11's bipolar items using nominal response models (NRM).
• To evaluate the psychometric properties and clinical relevance of the German PDS-ICD-11.

Main Methods:

• Administered the German PDS-ICD-11 and other self-report measures to a general population sample of 1,228 individuals.
• Employed nominal response models (NRM) to analyze the latent structure and item scoring assumptions.
• Correlated PDS-ICD-11 scores with measures of personality disorder severity, and Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and ICD-11 maladaptive trait domains.

Main Results:

• NRM indicated an acceptable fit for a unidimensional model of the PDS-ICD-11, with minor deviations from the theoretical scoring scheme.
• The total score demonstrated sufficient reliability and meaningful correlations with other PD severity measures.
• The total score was most strongly associated with negative affectivity, with weaker links to antagonism and anankastia.

Conclusions:

• The scoring scheme for the PDS-ICD-11 items is deemed acceptable, and the German version's psychometric properties align with initial findings.
• The PDS-ICD-11 total score primarily captures internalizing rather than externalizing personality pathology.
• Future research should explore the PDS-ICD-11's diagnostic efficiency using multi-method, longitudinal designs and clinical/forensic samples.