Under-identification of personality disorder among in-patient mental health service users: implications for CBT therapists

The identification of personality disorder among mental health service users is problematic but important because it is associated with high levels of comorbidity and possibly ineffective service delivery. This study assessed the prevalence of personality disorder using the Millon Clinical Multiaxial Inventory – 3rd edition (MCMI-III) compared with prevalence using frequency of assignment of diagnosis in people referred to an in-patient CBT clinical psychology service. Prevalence rates differed from 85% (MCMI-III) to 16% (diagnosis) using these different measures. Reasons for this difference and implications for CBT therapists' practice are discussed.