National trends in co-use of opioids and methamphetamine among people who inject drugs, 2012-2018

Reports from substance use disorder treatment admissions have described a trend of rapidly increasing overlapping methamphetamine and opioid use throughout the United States in the past twenty years. We used data from the 2012, 2015, and 2018 cycles of the National HIV Behavioral Surveillance (NHBS) project among people who inject drugs (PWID) to describe trends in methamphetamine-opioid co-use over time and in different US Census regions. We compared the demographic, socio-economic, sexual health, and drug use behavioral characteristics of people who co-used compared to people who primarily used one of these drugs. Methamphetamineopioid co-use increased from 4.3 % in 2012 to 14.3 % in 2018 in the national NHBS-PWID sample. Co-use was most prevalent in the West and increased the most in the Northeast. Younger age, frequent drug injection, opioid overdose in the past year, and sharing syringes and other injection equipment were significantly associated with methamphetamine-opioid co-use compared to all other drug use patterns. The widespread change in drug use patterns and the higher-risk behavior associated with co-use signal the need for swift and coordinated public health action to expand harm reduction and treatment services and to develop data-informed clinical guidelines to serve this growing population.