The impact of comorbid psychiatric disorders on methadone maintenance treatment in opioid use disorder: a prospective cohort study

Tea Rosic,1 Leen Naji,2 Monica Bawor,3 Brittany B Dennis,3 Carolyn Plater,4 David C Marsh,5 Lehana Thabane,6–8 Zainab Samaan6–11 1St Joseph’s Healthcare, 2Michael G DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada; 3St George’s University of London, London, UK; 4Canadian Addiction Treatment Centre, Richmond Hill, 5Northern Ontario School of Medicine, Sudbury, 6Biostatistics Unit, Research Institute, St Joseph’s Healthcare, 7Department of Clinical Epidemiology and Biostatistics, McMaster University, 8Peter Boris Centre for Addictions Research, 9Mood Disorders Research Unit, St Joseph’s Healthcare, 10Population Genomics Program, Chanchlani Research Centre, 11Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada Objective: There is a significant interindividual variability in treatment outcomes in methadone maintenance treatment (MMT) for opioid use disorder (OUD). This prospective cohort study examines the impact of comorbid psychiatric disorders on continued illicit opioid use in patients receiving MMT for OUD. Methods: Data were collected from 935 patients receiving MMT in outpatient clinics between June 2011 and June 2015. Using linear regression analysis, we evaluated the impact of having a comorbid psychiatric disorder on continued illicit opioid use during MMT, adjusting for important confounders. The main outcome measure was percentage of opioid-positive urine screens for 6 months. We conducted a subgroup analysis to determine the influence of specific comorbid psychiatric disorders, including substance use disorders, on continued illicit opioid use. Results: Approximately 80% of participants had at least one comorbid psychiatric disorder in addition to OUD, and 42% of participants had a comorbid substance use disorder. There was no significant association between having a psychiatric comorbidity and continuing opioid use (P=0.248). Results from subgroup analysis, however, suggest that comorbid tranquilizer (β=20.781, P