Executive summary

Introduction: Post traumatic stress disorder (PTSD) and substance use disorder (SUD) often co-occur, yet little is known of the relationship between heroin dependence and PTSD. With increasing rates of heroin dependence it is important that the prevalence and correlates of PTSD are examined. The present study is the first to examine PTSD in a large sample of heroin users in Australia.

Method: The current study utilises data collected as part of the New South Wales (NSW) component of the Australian Treatment Outcome Study (ATOS). ATOS is a 12 month longitudinal study of entrants to treatment for heroin dependence. Participants were recruited from 19 treatment agencies randomly selected from within three main treatment modalities (methadone/buprenorphine maintenance, detoxification, and residential rehabilitation) stratified by area health service. Five hundred and thirty five individuals entering treatment and 80 heroin users not seeking treatment were recruited into the study and interviewed by trained researchers using a structured questionnaire. Valid and reliable instruments including the Opiate Treatment Index (OTI), Short Form-12 (SF-12) and the Composite International Diagnostic Interview (CIDI) were used to measure drug use, health, criminal activity, PTSD and other psychiatric comorbidity.

Results

Prevalence of trauma exposure and PTSD
Almost all (92%) of the sample had experienced at least one traumatic event during their lives with the majority experiencing multiple traumas. PTSD was highly prevalent among this group of heroin users (41%), with women being more likely to develop PTSD than men following exposure to trauma. Those with PTSD were presented across all treatment modalities. The highest proportion was in the residential rehabilitation group and the lowest in the non-treatment group.

Most upsetting trauma and conditonal risk of developing PTSD
A higher prevalence of PTSD was found among those who had been raped or sexually molested Importantly, it is apparent from this analysis that gender differences in the lifetime prevalence of PTSD arise from gender differences in responses to trauma exposure rather than from differences between the genders in rates of exposure to traumatic events.

PTSD and heroin use: order of onset
There was no clear temporal sequence of PTSD and heroin use.

Drug use and heroin use history
Those with PTSD had a more extensive history of polydrug use, having used a greater number of drug classes in their lifetime and in the preceding 6 months compared to those without PTSD. Although the frequency of current heroin use was similar for those with and without PTSD, those with PTSD were more likely to have experienced heroin overdose.

Criminal activity
Those with PTSD were more likely to have committed violent crime in the preceding month.

Physical and mental health
Of major clinical importance are the high rates of comorbidity found among those with PTSD. Those with PTSD had poorer general physical and mental health, and were more likely to have current Major Depression, have attempted suicide, and screen positive for Borderline Personality Disorder.

Patterns of treatment seeking and health service utilisation
Those with PTSD had a greater number of previous treatment attempts for heroin dependence than those without PTSD. They were also more likely to have consulted a social worker or counsellor and a General Practitioner, and to have been prescribed anti-depressants or other psychotropic medications (i.e., narcotic analgesics and antipsychotics) in the preceding month.

Independent factors associated with PTSD
Screening positive for BPD, being female, nominating sexual molestation as the most stressful event, having experienced a greater number of traumatic events, and being older were significant predictors of a positive PTSD diagnosis.

Conclusion: Given that PTSD and its related psychiatric comorbidity may be associated with poorer substance abuse treatment outcomes it is important that clinicians are aware of the high prevalence of the disorder among heroin users. As the first large scale longitudinal study to examine PTSD among people with heroin dependence, future reports from ATOS will present data on the impact of PTSD on treatment outcomes 3 and 12 months post treatment entry.

Citation: Mills, J., Lynskey, M., Teesson, M., Ross, J. and Darke, S. (2003) Prevalence and correlates of post traumatic stress (PTSD) among people with heroin dependence: Findings from the Australian Treatment Outcome Study (NSW), Sydney: National Drug and Alcohol Research Centre.