Field trial of a putative research algorithm for diagnosing ICD-11 personality disorders in psychiatric patients: 1. Severity of personality disturbance.

This preliminary field trial examines the reliability and validity of a proposed research algorithm for diagnosing International Classification of Diseases (ICD)-11 personality disorders and its association with other psychiatric assessments for the primary classification of a single dimension of the five severity levels of personality dysfunction. In total, 137 psychiatric patients (119 with personality disorders and 18 without personality disorders) in Korea were assessed. In the first part of the study, inter-rater reliability was evaluated with an independent assessment of personality (personality assessment schedule). In the second part of the study, (1) the algorithm that identified any personality disturbance was compared with the ICD-10 and DSM-IV personality disorder diagnostic equivalents, and (ii) the four levels of severity were examined for their associations with clinical pathology and social functioning. The results showed good agreement between the algorithm and the test instruments for identifying a personality disorder. A graded increase in clinical pathology and social dysfunction was observed with increasing severity of personality disorder. These findings suggest that a simple algorithm for recording severity of a personality disturbance had both construct validity and was useful in practice, which supports severity classification as a valuable concept. These findings need to be confirmed in other cultures and ethnic groups.