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Abstract
Comorbidity between substance use disorders and post traumatic stress disorder (PTSD) is common. Despite evidence to suggest that people with heroin dependence are at particular risk of PTSD, there is a dearth of research focussing on the interrelationship between these disorders. The present thesis aims to identify the prevalence of PTSD among people with heroin dependence, the correlates of this comorbidity, and its impact on treatment outcomes, the utilisation of treatment services, and treatment costs.
Study 1 examines the epidemiology of PTSD and heroin dependence among 10,641 Australian adults who participated in the National Survey of Mental Health and Wellbeing. The prevalence of PTSD was highest among people with heroin or other opioid use disorders compared with any other drug class (33.2%). Comorbid PTSD was associated with poorer occupational functioning, and poorer physical and mental health.
While general population studies provide crucial population estimates they do not allow for a detailed examination of the relationship between highly disabling but low prevalence disorders. The remaining studies were undertaken using a sample of 615 treatment seeking and non-treatment seeking dependent heroin users. Study 2 examines the prevalence and correlates of this comorbidity. PTSD was common (lifetime 41%; current 31%) and was associated with a more severe clinical profile.
Studies 3 and 4 were based on follow-up data on this large cohort. Study 3 is the first study to examine the impact of PTSD on 2 year treatment outcomes for heroin dependence. Across the 2 year period, those with current PTSD at baseline performed more poorly in terms of their occupational functioning, physical and mental health. Study 4 found that this did not equate to the greater use of treatment services or an increased cost to the health care system among those with PTSD.
It is concluded that PTSD and heroin dependence are highly comorbid conditions, and that this comorbidity is associated with poorer functioning and poorer treatment outcomes. Individuals entering treatment for heroin dependence should be assessed for PTSD so that they may receive appropriate treatment and referral. Further research is also needed to determine how best to treat this comorbidity.