Critical developments in the assessment of personality disorder.

BACKGROUND The assessment of personality disorder is currently inaccurate, largely unreliable, frequently wrong and in need of improvement. AIMS To describe the errors inherent in the current systems and to indicate recent ways of improving personality assessment. METHOD Historical review, description of recent developments, including temporal stability, and of studies using document-derived assessment. RESULTS Studies of interrater agreement and accuracy of diagnosis in complex patients with independently established personality status using document-derived assessment (PAS-DOC) with a four personality cluster classification, showed very good agreement between raters for the flamboyant cluster B group of personalities, generally good agreement for the anxious/dependent cluster C group and inhibited (obsessional) cluster D group, but only fair agreement for the withdrawn cluster A group. Overall diagnostic accuracy was 71%. CONCLUSIONS Personality function or diathesis, a fluctuating state, is a better description than personality disorder. The best form of assessment is one that uses longitudinal repeated measures using a four-dimensional system.