Impact of recent methamphetamine use on treatment outcomes among individuals initiating medications for opioid use disorders in rural treatment settings: a 1-year retrospective cohort study.

INTRODUCTION

Rates of N-methylamphetamine (methamphetamine) use in rural areas of the US have been steadily increasing, particularly among individuals who are already struggling with opioid use disorder. Despite this alarming trend, there remains a significant gap in our understanding of how methamphetamine use affects treatment response for those undergoing treatment with medications for opioid use disorder (MOUD). This study aimed to explore the predictive role of methamphetamine urinalysis (UA) results at intake in treatment retention and in opioid and methamphetamine use over time among individuals seeking MOUD treatment in four clinics located in rural areas. The study was conducted across four clinics situated in rural areas, where access to addiction treatment services is known to be limited.

METHODS

Clinical data for this study were collected between January and December 2019. A substantial number of participants were enrolled from those patients initiating treatment in 2019 in four clinics in rural Oregon. Data included intake demographics, attendance, and monthly opioid and methamphetamine UA results over a 1-year period. Our primary outcomes were opioid and methamphetamine use, and treatment retention over a 1-year period. Objective verification of opioid and methamphetamine use was determined using UA results collected once per month. Treatment retention was determined considering the number of days elapsed from treatment intake to treatment dropout. Generalized estimating equations were used to compare methamphetamine and opioid use over time, and Kaplan-Maier survival analysis was used to compare treatment retention by methamphetamine UA result at intake.

RESULTS

A total of 554 patients enrolled at one of the four rural MOUD clinics, of whom 277 (50%) had a negative methamphetamine and 277 (50%) had a positive methamphetamine UA result at intake. Participants were mostly White individuals (89.5%), half of participants were male (54.5%), and the mean age was 36.8 years (standard deviation 10.8 years). About a third were unemployed (32.3%), more than a quarter reported legal problems (26.2%), and 5.4% were currently homeless. Compared to those testing negative for methamphetamine, patients initiating MOUD treatment with a positive methamphetamine UA were more likely to be unemployed (36.5% v 28.2%; p=0.048) and to have a positive opioid UA result at intake (88.4% v 45.8%; p<0.001). A negative methamphetamine UA result at intake was associated with fewer positive methamphetamine UA results over time (p=0.022) but was not associated with either better treatment response for opioid use over time (p=0.849) or treatment retention (p=0.51).

CONCLUSION

While patients who had negative methamphetamine UA results when initiating MOUD treatment had higher rates of methamphetamine abstinence over time, methamphetamine UA results at intake did not predict worse treatment outcomes in terms of opioid use and treatment retention for patients receiving MOUD in rural areas. Our findings highlight demographic and profile differences between patients who use methamphetamine in MOUD rural settings, and they identify significant gaps in existing knowledge regarding the effects of methamphetamine use on MOUD treatment response. Such findings underscore a critical need for further research to be conducted, specifically among rural populations seeking MOUD treatment.