Long-term follow-up assessment of opioid use outcomes among individuals with comorbid mental disorders and opioid use disorder treated with buprenorphine or methadone in a randomized clinical trial

Abstract

Aims: To investigate whether reduction in opioid use differs when treated by either buprenorphine-naloxone (BUP) or methadone (MET) among adults with comorbid opioid use disorder (OUD) and mental disorders.

Design, setting and participants: In a randomized controlled trial, adults with OUD were randomized to 24 weeks of either BUP or MET treatment and were followed up in 3-yearly assessments. The present secondary analyses were based on 597 participants who completed all assessments.

Measurements: The outcome measure was the number of days of using opioids per month during the follow-up period. The Mini-International Neuropsychiatric Interview (MINI) was used to classify participants into three groups: life-time mood disorder (n = 302), life-time mental disorder other than mood disorder (n = 114) and no mental disorder (n = 181). Medication treatment (BUP, MET, no treatment) during the follow-up period was a time-varying predictor.

Findings: Based on zero-inflated Poisson (ZIP) mixed regression analysis, it was found that relative to no treatment, opioid use during the follow-up was significantly reduced by BUP [odds ratio (OR) = 0.12, 95% confidence interval (CI) = 0.07-0.21 for any use; risk ratio (RR) = 0.77, 95% CI =0.66-0.89 for days of use] and by MET [OR = 0.33, 95% CI = 0.25-0.45 for any use; RR = 0.78, 95% CI = 0.72-0.84 for days of use]. Relative to MET, BUP was associated with a lower likelihood of any opioid use among participants with mood disorders (OR = 0.52, 95% CI = 0.36-0.74) and for participants without mental disorder (OR = 0.37, 95% CI = 0.21-0.66) and fewer number of days using opioids (RR = 0.37, 95% CI = 0.25-0.56) among participants with other mental disorders.

Conclusions: Among adults with comorbid opioid use disorder and mental disorders, treatment with buprenorphine-naloxone produced greater reductions in opioid use than treatment with methadone.

Trial registration: ClinicalTrials.gov NCT01592461.

Keywords: Buprenorphine; comorbidity; longitudinal; mental health disorder; methadone; opioid use disorder.

© 2021 Society for the Study of Addiction.

Figures

Figure 1

Consolidated Standards of Reporting Trials (CONSORT) diagram: sample sizes and attrition at each stage

Figure 2

Percentage of participants receiving medication treatment for opioid use disorder (MOUD) during the follow-up period by mental disorder group [Colour figure can be viewed at wileyonlinelibrary.com]

Figure 3

Estimated days of opioid use per month during follow-up by mental disorder groups [Colour figure can be viewed at wileyonlinelibrary.com] Note: BUP: Buprenorphine-naloxone; MET: Methadone. Since treatment status is a time-varying covariate, the number of participants in each treatment type varies for each month. Across the follow-up period, on average, 11.5% of the participants were in BUP treatment, 42.5% in MET treatment, and 43.2% in neither treatment.