Examining childhood trauma and comorbid mental disorders among people with opioid use disorder

Abstract

Opioid use disorder (OUD) is characterised by persistent opioid use despite the experience of harm. Current literature suggests that childhood trauma and mental disorders are risk factors for illicit OUD. However, little is known about the effects of childhood trauma and mental disorders on OUD-related harm. Our understanding of this relationship is also limited by imprecise childhood trauma and mental disorder prevalence data; few studies on people prescribed opioids for chronic non-cancer pain (CNCP); and a lack of research on interventions that reduce harm related to childhood trauma and mental disorders among people with OUD. This thesis uses multiple study methods on data from several different opioid-using populations to broaden our understanding of the relationship between childhood trauma, mental disorders, and OUD. The studies in this thesis aimed to 1) estimate the prevalence of specific childhood trauma types and mental disorders among people with OUD; 2) investigate childhood trauma as an independent risk factor for OUD among a large sample of people prescribed opioids for CNCP; 3) explore the effects of childhood trauma and mental disorders on OAT engagement, crime, and mortality among people with illicit OUD; and 4) examine the associations between OAT and causes of mortality, including suicide, among people with OUD. Multiple key findings emerged from this thesis. The first two studies confirmed that people with OUD experience childhood trauma and mental disorders at far higher rates than the general population. The third study of people prescribed opioids for CNCP found that childhood trauma independently increased the risk of OUD after controlling for mental disorders and other known OUD risk factors. The fourth study found that childhood trauma and most mental disorders were related to poorer OAT engagement and higher criminal offending rates among people with OUD. The fifth study, a systematic review and meta-analysis, found that OAT was associated with reduced risk of multiple causes of mortality, including suicide, among people with OUD. Findings from these studies highlight the importance of addressing childhood trauma and mental disorders in both the treatment of OUD and the management of CNCP with pharmaceutical opioids. The results can inform clinical guidelines, policy, and future research that impact people with OUD and those prescribed opioids for CNCP.