Methamphetamine Use and Its Correlates among Individuals with Opioid Use Disorder in a Midwestern U.S. City.

Background: U.S. is experiencing a surging trend of methamphetamine use among individuals who use opioids. More research is needed to characterize this emerging "twin epidemic." Objectives: The study aims to identify social and behavioral characteristics associated with methamphetamine use among individuals with opioid use disorder (OUD) in the Dayton, Ohio, area, an epicenter of the opioid crisis and an emerging frontier of methamphetamine epidemic. Methods: 357 adult individuals with current OUD were recruited using targeted and respondent-driven sampling. Structured interviews collected information on social and drug use characteristics. Multivariable Logistic Regression was used to identify characteristics associated with the past 6-month use of methamphetamine. Results: 49.7% were female, and 88.8% were non-Hispanic whites. 55.6% used methamphetamine in the past 6-months, and 84.9% reported first use of methamphetamine after initiation of illicit opioids. Methamphetamine use was associated with homelessness (aOR = 2.46, p = .0001), lifetime history of diverted pharmaceutical stimulant use (aOR = 2.97, p < .001), injection route of heroin/fentanyl use (aOR = 1.89, p = .03), preference for fentanyl over heroin (aOR = 1.82, p = .048), lifetime history of extended-release injectable naltrexone (Vivitrol)-based treatment (aOR = 2.89, p = .003), and more frequent marijuana use (aOR = 1.26, p = .04). Discussion: The findings point to the complexity of motivational and behavioral pathways associated with methamphetamine and opioid co-use, ranging from self-treatment and substitution behaviors, attempts to endure homelessness, and greater risk taking to experience euphoria. More research is needed to understand the causal relationships and the association between methamphetamine and Vivitrol use. Public health responses to the opioid crisis need to be urgently expanded to address the growing epidemic of methamphetamine use.