Borderline personality disorder, antisocial personality disorder and risk-taking among heroin users: findings from the Australian Treatment Outcome Study (ATOS).

AIM: To determine the relationship between borderline personality disorder (BPD), antisocial personality disorder (ASPD) and harm among current heroin users.
DESIGN: Cross-sectional survey.
SETTING: Sydney, Australia. PARTICIPANTS: 615 current heroin users.
FINDINGS: Forty-six percent met criteria for BPD, 71% for ASPD, and 38% met criteria for both diagnoses. ASPD was related to attempted suicide, lifetime overdose, polydrug use, depression and overall psychological distress. BPD was also related to each of these risk domains, and to needle risk and recent suicide as well. When analysed separately, both BPD and ASPD thus appeared to predict harm. For the purposes of further analysis, the relationships between BPD, ASPD and harm, the sample was divided into four independent diagnostic groups: no diagnosis (ND, 21%), ASPD only (ASPD, 33%), BPD only (BPD, 7%), ASPD plus BPD (DUAL, 38%). The division of the sample into four distinct diagnostic groups produced substantially different results. There were strong relationships between BPD and attempted suicide, needle sharing and psychopathology. In none of these domains did the ASPD group significantly differ from the ND group. Also, the levels of harm among the DUAL group were identical to BPD, suggesting no additive risk from ASPD. Thus, while initial analyses suggested an increased risk for ASPD patients for suicide and psychopathology, these relationships disappeared after BPD was taken into account. The only domain in which there appeared to be an additive risk for ASPD and BPD was heroin overdose.
CONCLUSIONS: The extensive comorbidity between BPD and ASPD means that, unless BPD is controlled for, artefactual relationships may emerge between ASPD and harm.