Suicidal behaviour and associated risk factors among opioid-dependent individuals: A case-control study

Aims: To examine suicidal behaviour and the associated risk factors among opioid-dependent cases and non-opioid-dependent controls. Design: Case-control study. Setting: Sydney, Australia. Participants: A total of 726 opioid-dependent cases and 399 non-opioid-dependent controls, matched on age, sex and employment status. Findings: Cases had significantly higher life-time prevalence of suicidal thoughts (66% versus 55%), suicide attempts (31% versus 20%) and multiple attempts (19% versus 11%) compared to controls. Cases were significantly more likely to indicate a severe intent to die (63% versus 43%). Both cases and controls who had attempted suicide were significantly more likely than others to suffer from substance use and psychological disorders, as well as childhood maltreatment. Risk factors which predicted suicide attempts were the same among cases and controls, including screening positive for borderline personality disorder, post-traumatic stress disorder and persistent suicidal thoughts. Conclusions: Although controls had elevated levels of suicidal behaviour compared to those seen in general population surveys, the prevalence of suicidal behaviour among cases was still much higher. Although opioid dependence was related to suicidal behaviour, it did not make a unique contribution to the risk of suicide attempts over and above the other risk factors identified.