NDARC Technical Report No. 283 (2007)
EXECUTIVE SUMMARY
Background: Suicide is a major public health issue, both among the general population and also among those suffering from a drug use disorder. The prevalence of lifetime suicide attempts is estimated at around 3.6% among community samples. In comparison, the prevalence of lifetime suicide attempts for individuals suffering from heroin dependence is around 30%.
A number of risk factors have been identified as contributing to increasing an individual’s risk of suicidal behaviour both among the general population and those with a drug use disorder. Generally the risk factors identified have been similar. Additional risk factors however, have been identified as unique among opioid dependent individuals. Furthermore, opioid dependent individuals typically suffer an increased number of risks. Some of the risk factors identified in the literature include social and demographic factors (such as sex and unemployment status), family characteristics and childhood experiences (such as parental loss or abuse as a child), personality traits (such as impulsivity), environmental factors (such as stressful life events), and psychiatric morbidity (such as depression or post-traumatic stress disorder (PTSD)).
To date, only one study has compared the prevalence and risk factors associated with suicidal behaviour among opioid dependent individuals and a control group; however, the control group participants did not suffer from any mental health disorders.
Aims: The current study aimed to examine the prevalence of suicidal behaviour and the risk factors associated with such behaviour among an opioid dependent case group, and a non-opioid dependent control group, matched in terms of age, sex and employment status. The design allowed a comparison to be made while controlling for opioid dependence, correlates of suicidal behaviour, and disadvantage. The specific aims of the current study were:
- to determine the prevalence of suicidal thoughts and behaviour among opioid dependent cases and non-opioid dependent controls;
- to compare the characteristics of the most serious suicide attempt reported among opioid dependent cases and non-opioid dependent controls; and
- to examine the risk factors associated with suicide attempts among opioid dependent cases and non-opioid dependent controls.
Method: This study utilised data collected as part of a large retrospective case-control study examining possible genetic influences upon opioid dependence and childhood trauma and their contribution to the development of opioid dependence. The study used a structured diagnostic interview.
The study employed a case-control design whereby opioid dependent cases were matched to non-opioid dependent controls in terms of age, sex and employment status, allowing a comparison of suicidal risk to be made and to control for opioid dependence. Eligibility criteria allowed the two groups to remain similar on some demographic characteristics but differing in terms of opioid exposure (cases were required to be dependent on opioids, whereas controls were required to have used opioids less than five times in their life).
Cases were recruited from opioid maintenance treatment clinics in New South Wales, Australia. Controls were recruited from employment centres, letterbox drops, medical centres, centrelink offices, libraries, street shopping malls, and local press, all of which serviced the same area as the treatment clinics to minimise the effects of population stratification.
Results: Cases had significantly higher lifetime prevalence of suicidal ideation, suicide plans and suicide attempts compared to controls. Cases were also significantly more likely to have made multiple attempts over their lifetime compared to controls. Cases were significantly more likely to indicate a more severe intent to die compared to controls, which was interesting considering no differences were identified among the types of methods used or the seriousness (in terms of medical treatment sought) reported by either group.
Female cases were found to be significantly more likely to report suicidal ideation and suicide attempts compared to male cases. Additionally, female cases were significantly more likely to make multiple attempts compared to male cases. No differences between males and females were found among controls.
Both cases and controls that had attempted suicide were significantly more likely than others to meet criteria for other substance use and psychological disorders. They were more likely to report childhood maltreatment, which included emotional abuse, neglect, physical abuse, and sexual abuse.
Multivariate analyses suggested that the risk factors that predicted suicide attempts were similar for cases and controls, namely: post-traumatic stress disorder (PTSD), screening positive for borderline personality disorder (BPD), and persistent suicidal thoughts. Additionally, sedative dependence was significant among cases, and unemployment plus stimulant dependence were significant among controls. Additional analyses, however, showed that opioid dependence did not make a unique contribution to suicidal risk.
Discussion: Although the prevalence of suicidal behaviour was high among the controls compared to community samples, opioid dependence appeared to substantially increase an individual’s risk of suicidal behaviour. Opioid dependence, however, did not make a unique contribution to suicidal risk over and above the other risk factors identified, which include BPD and PTSD. Despite differing levels of suicidal behaviour among cases and controls, the current study identified that the risk factors for suicide attempts remain essentially the same.
Citation: Maloney, E,, Degenhardt, L., Darke, S., Mattick, R.P. & Nelson, E. (2007) The prevalence and associated risk factors of suicidal behaviour among opioid dependent persons: A case-control study, Sydney: National Drug and Alcohol Research Centre.