The validity of two diagnostic systems for personality disorder in people with intellectual disabilities: a short report

<p>Background -- Over the last 10 years there has been greater interest in the diagnosis ofpersonality disorder (PD) in people with intellectual disabilities (ID). One important characteristic ofa diagnostic system is that it should have validity as a contribution to utility. PD has been found tohave a predictive relationship with violence and the present study reviews two methods for thediagnosis of PD in offenders with ID in order to evaluate the utility of the diagnoses.Method --212 offenders with ID were recruited from three settings -- maximum-security,medium/low security and community services. Three research assistants were trained over a period oftwo weeks in order to increase reliability for the extraction of information from the case notes and thediagnosis of PD. Diagnoses of PD in the case files were compared with a structured system ofdiagnosis based on DSM IV traits.Results – There were significant differences between the two systems with a significantlyhigher frequency of PD diagnosis in the community forensic setting in the structured assessmentsystem. There was no relationship between the case files diagnosis of PD and future violence but therewas a significant predictive relationship between the structured diagnosis of PD and future violencewith an AUC=.62.Conclusions -- Only the structured assessment of PD had utility for the prediction of violence.Reasons for the differences between the systems are discussed and suggestions made on how adiagnosis of PD can be structured for the busy clinician.</p>