Psychiatric Comorbidity in Patients with Opioid Use Disorder

Abstract

Objective: Opioid use disorder (OUD) remains a major public health problem within Canada and worldwide. Increasing our understanding of psychiatric comorbidity in this population is the focus of this thesis. Methods: We used observational cohort data from two prospective studies of individuals with OUD receiving opioid agonist treatment (OAT). These data allowed us to examine risk factors for psychological symptoms and psychiatric comorbidities, to examine differences between youth and adults, and to assess the sensitivity and specificity of self-reported diagnoses against those made using a validated tool. We linked cohort data to Provincial health administrative data holdings to explore mental healthcare service use and associated costs. Discoveries: This work provides new information on psychiatric comorbidity among individuals receiving treatment for OUD and carries implications that can inform future research to shape clinical care. The main conclusions drawn from this work were: 1) routine assessment of psychological symptoms, including suicidal ideation, in this population is warranted; 2) self- report of psychiatric disorders is not sufficiently sensitive to identify psychiatric comorbidity and other methods such as validated tools should be considered; 3) trauma and post-traumatic stress disorder are common in individuals with OUD and their impact may not be captured by solely measuring substance-related outcomes in treatment; 4) youth with OUD differ from adults in their health risk behaviours and psychiatric comorbidities and likely require distinct services and supports; and 5) outpatient non-substance-related mental healthcare for individuals with OUD is provided largely by primary care physicians for whom increased resources and training are needed, and emergency department visits and hospitalizations (which are costlier to the system) are not uncommon. Conclusion: Psychiatric comorbidity is prevalent in OUD and integrated mental health and addictions treatment requires clinical and research attention. Future studies are needed to test interventions and build an evidence base to inform clinical management.