Association between methamphetamine use and retention among patients with opioid use disorders treated with buprenorphine

Background: Methamphetamine use is increasing in parts of the U.S., yet its impact on treatment for opioid use disorder is relatively unknown. Methods: The study utilized data on adult patients receiving buprenorphine from Washington State Medication Assisted Treatment-Prescription Drug and Opioid Addiction program clinics between November 1, 2015 and April 31, 2018. Past 30-day substance use data were collected at baseline and 6-months, as well as date of program discharge. Cox proportional hazards regression was used to estimate the relative hazards for treatment discharge comparing methamphetamine users at baseline with non-users, adjusting for site, time period, age, gender, race, ethnicity, and education. For a subset of patients with data, we describe the proportion of individuals reporting methamphetamine use at baseline versus 6-months. Results: The sample included 799 patients, of which 237 (30%) reported using methamphetamine in the past 30 days; of those, 156 (66%) reported 1-10 days of use, 46 (19%) reported 11-20 days of use, and 35 (15%) reported 21-30 days of use. Baseline methamphetamine use was associated with more than twice the relative hazards for discharge in adjusted models (aHR = 2.39; 95% CI: 1.94-2.93). In the sub-sample with data (n = 516), there was an absolute reduction of 15% in methamphetamine use: 135 (26%) reported use at baseline versus 57 (11%) at follow-up. Conclusions: In summary, this study found that patients who concurrently used methamphetamine were less likely to be retained in buprenorphine treatment compared to non-users. For persons who were retained, however, methamphetamine use decreased over time.