Validation of the Personality Disorder Severity for ICD-11 (PDS-ICD-11) Scale in a Danish Mixed Clinical and Prison Treatment Sample

The International Classification of Diseases, 11th Edition (ICD-11) has adopted a new model for the diagnosis of personality disorder (PD), and novel measures have therefore been developed to assist in its assessment. This study examined the psychometric properties of the Personality Disorder Severity ICD-11 (PDS-ICD-11) scale in a mixed sample of Danish adults in prison (n = 101; 100% males; Mage = 34.57, SDage = 9.27) or in a rehabilitation program (n = 132; 64% males; Mage = 39.47, SDage = 11.60) with co-occurring substance use dependency and personality pathology. Participants were administered the PDS-ICD-11, Level of Personality Functioning Scale-Brief Form 2.0 (LPFS 2.0), World Health Organization Well-being Index (WHO-5), Symptom Checklist-90-Revised (SCL-90-R), Personality Inventory for DSM-5 Short Form (PID-5-SF) and the Schema Mode Inventory (SMI). The PDS-ICD-11 items conformed to a unidimensional structure, and the total score demonstrated relevant associations with severity indexes, maladaptive personality traits, well-being and dysfunctional schema modes. The PDS-ICD-11 was similarly correlated with both internalising and externalising measures of personality dysfunction across the sample, with the incarcerated sample demonstrating stronger associations with externalising personality traits. Overall, these findings support the validity and utility of the PDS-ICD-11 for the assessment of ICD-11 PD in externalising forensic and rehabilitation samples.