RESUMEN
Introduction: Although methamphetamine use is rising in the United States, its impacts on patient outcomes among persons undergoing treatment for opioid use disorder (OUD) remain unclear. This study aims to assess the association between baseline methamphetamine/amphetamine (MA/A) use and subsequent illicit opioid use among patients with OUD initiating buprenorphine in an office-based setting. Methods: We conducted a secondary analysis of a pilot randomized controlled trial of a behavioral mobile health intervention for buprenorphine adherence conducted over a 12-week study period at two clinic sites. The study defined baseline MA/A use by a positive urine drug test (UDT) and/or self-report of use within the past 30-days. Separate Poisson regression models with robust standard errors evaluated associations between MA/A and: i) illicit opioid use measured by weekly UDT (primary) and ii) self-reported past 30-day use at end of study (secondary). Other secondary outcomes included buprenorphine positive UDTs throughout the study and retention in OUD treatment at both weeks 12 and 24 post-randomization. Results: At baseline, 28 (36%) of the 78 participants had MA/A use and use was associated with a statistically significant increase in risk of testing positive for illicit opioids on UDT during the study follow-up period (adjusted relative risk (aRR)=1.54; 95% CI=1.09-2.17; p=0.015), as well as an increased risk for reported past 30-day illicit opioid use at week 12 (aRR=3.86; 95% CI=1.47-10.18; P=0.006). The study found no significant associations between MA/A use and buprenorphine positive UDT or retention in OUD treatment. Conclusions: In this sample of patients initiating buprenorphine, methamphetamine/amphetamine use at baseline was associated with illicit opioid use over a 12-week period. These findings demonstrate how co-use of methamphetamine can impede attainment of ideal OUD treatment outcomes.