Psychiatric comorbidity and treatment outcomes in patients with opioid use disorder: Results from a multisite trial of buprenorphine-naloxone and methadone

Background: Individuals treated for opioid use disorder (OUD) have high rates of psychiatric disorders potentially diminishing treatment outcomes. We examined long-term treatment experiences and outcomes by type of psy-chiatric disorder among participants who participated in the Starting Treatment with Agonist Replacement Therapies (START) study and its follow-up study. Methods: We categorized the 593 participants who completed the Mini-International Neuropsychiatric Interview (MINI) during the START follow-up study into four mutually exclusive groups to indicate current psychiatric diagnosis: 1) bipolar disorder (BPD; n = 51), 2) major depressive disorder (MDD; n = 85), 3) anxiety disorder (AXD; n = 121), and 4) no comorbid mental disorder (NMD; n = 336). We compared participants' baseline characteristics and treatment outcomes. Results: Groups with mental disorders had worse substance use outcomes and poorer psychosocial functioning than the NMD group. Participants with BPD had significantly more self-reported days using opioids (Mean: 8.6 for BPD vs. 3.4 days for NMD, p < 0.01) and heroin (Mean: 6.4 for BPD vs. 2.0 for MDD, 3.1 days for NMD, p < 0.05) in the 30 days prior to the final interview. Compared to patients without mental disorders, patients with MDD spent more time engaged with OUD pharmacotherapy during the similar to 16-month period between MINI and final interview (mean: 71.6 % vs. 50.6 %; p < 0.001). Conclusions: Our results show that treatment outcomes in individuals with OUD vary by psychiatric comorbidity groups, which supports the need for mental health assessment and treatment for psychiatric conditions in the context of pharmacotherapy for patients with OUD.