Preliminary studies of the ICD-11 classification of personality disorder in practice

Objective: This study aims to compare ICD-10 and putative ICD-11 classifications of personality disorder in different clinical populations. Design: Prospective recording of ICD-10 and ICD-11 personality disorder classifications was carried out in (1) an anxious medical population, (2) an acute psychiatric in-patient population and (3) a retrospective recording of a mixed anxiety depression cohort in which all baseline data were scored from baseline information using the ICD-11 classification and compared with the original ICD-10 assessments. Method: Comparison of ICD-10 and ICD-11 prevalence of personality disorder in each population was carried out. Results: Data from 722 patients were recorded. Using the ICD-10 criteria, the prevalence of generic personality disorder was 33.8% compared with 40.4% using the ICD-11 ones (χ2=6.7; P<0.01), with 103 (14.3%) discordant assessments. Using the severity definitions in ICD-11, 34.3% of patients had personality difficulty. Severity level varied greatly by population; severe personality disorder was five times more common in the inpatient group. The four domain traits originally denoted as qualifying severity in ICD-11, negative affective, dissocial, anankastic and detached, were linked to anxious, borderline, dissocial, anankastic and schizoid personality disorders in ICD-10. Many patients had pathology in two or more domains. Conclusions: The ICD-11 classification of personality disorder yields somewhat higher levels of personality dysfunction than ICD-10, possibly because the age range for the onset of diagnosis is now flexible. The range of severity levels make the classification more useful than ICD-10 in clinical practice as it identifies the greater pathology necessary for intervention.