Psychiatric Comorbidities and Risks of Death, Non-Fatal Overdose, and Self-Harm in Opioid Agonist Therapy: A Retrospective Cohort Study

Introduction: Psychiatric disorders are common among patients with opioid use disorder (OUD). Opioid agonist therapy (OAT) is an effective treatment for OUD, but outcomes for patients with psychiatric comorbidities remain understudied. This study aimed to examine the connections between psychiatric comorbidities and outcomes in individuals undergoing OAT. Methods: We retrospectively collected data from the Wellbeing Services County of Southwest Finland clinical registry. The cohort included 1235 patients receiving OAT from January 1, 2004, to April 15, 2021. Patients attending OAT, psychiatric diagnoses, overdoses, and self-harm were identified from the registry data using ICD-10 codes. In cases of death, the register also included the date of death. We analyzed associations between psychiatric comorbidities and outcomes using Cox regression for death and logistic regression for non-fatal overdose and self-harm. Results: We identified the prevalence of the following psychiatric comorbidities: non-substance use disorder (non-SUD) psychiatric disorders (39.0%), psychosis (17.0%), mood disorders (29.1%), anxiety disorders (26.2%), personality disorders (20.7%), and other SUDs not related to opioids (other SUDs) (61.4%). After adjusting for all covariates, we found an association between alcohol use disorder (AUD) (hazard ratio = 1.54, 95% confidence interval [CI] = 1.06–2.22) and a higher risk of death during OAT. Additionally, non-SUD psychiatric disorders (overdose: odds ratio [OR] = 1.64, 1.14–2.36; self-harm: OR = 1.50, 1.03–2.18), psychosis (overdose: OR = 1.89, 1.29–2.79; self-harm: OR = 1.87, 1.26–2.78), and other SUDs (overdose: OR = 2.61, 1.81–3.83; self-harm: OR = 2.56, 1.74–3.82) were associated with higher odds of both overdose and self-harm. Conclusion: The study emphasizes the need for screening and secondary preventive measures for psychosis and other SUDs (particularly AUD) in OAT settings.