Understanding methamphetamine and opioid co-use: national trends and local harm reduction strategies for overlapping illicit drug use

In the past 20 years, the United States has seen a remarkable increase the use of both methamphetamine and opioids, used concurrently or simultaneously. A more detailed picture is needed to understand where methamphetamine-opioid co-use is increasing nationally, as well as the characteristics of people who co-use. Methamphetamine-opioid co-use has become particularly prevalent in Seattle, WA, yet the rationale for co-use among people who use drugs in this important region is not yet clear. More harm reduction tools to serve the growing number of people who co-use in Seattle are needed. Methods: First, we used data from the 2012, 2015, and 2018 cycles of the National HIV Behavioral Surveillance (NHBS) project in people who inject drugs (PWID) to describe trends in methamphetamine-opioid co-use over time and in different Census regions. We also compared the demographic, socio-economic, sexual health, and drug use behavioral characteristics of people who co-used compared to people who primarily used one drug (Chapter 1). Second, we conducted in-depth semi-structured interviews with people who regularly used both methamphetamine and opioids recruited from a syringe services program (SSP) in downtown Seattle (N=21). We conducted an interpretive descriptive analysis of the data informed by the social-ecological framework to identify themes in the rationale behind methamphetamine-opioid co-use for our participants (Chapter 2). And last, we evaluated access to and interest among Seattle-area PWID in a potential harm reduction strategy to promote safer consumption by facilitating a switch from injection to safer routes such as smoking or oral consumption with free safer smoking equipment. Using data from the Seattle 2018 NHBS survey of people who inject drugs (N=555), we described whether respondents had access to safer smoking equipment, whether they were interested in getting it, and if they thought access did or would reduce their injection frequency (Chapter 3). Results: In the national data, we found that methamphetamine-opioid co-use increased from 14.0% in 2012 to 26.3% in 2018 in the overall NHBS sample. Co-use was most prevalent in the West and increased the most in the Northeast. Younger age, opioid overdose in the past year, sharing syringes, and sharing other injection equipment were significantly associated with methamphetamine-opioid co-use compared to all other drug use patterns. In our qualitative study, we identified two overarching themes in the rationale of methamphetamine-opioid co-use: availability and function. For many, methamphetamine and opioids were readily available in their social networks, in community sources, and through the fluctuating illicit drug market. Methamphetamine and opioids served a number of functional uses individually and in families and communities. We also identified that houselessness was an environment in which the availability and function of methamphetamine and opioids were uniquely elevated. And last, we found that among Seattle-area NHBS-PWID participants, just 12% reported access to free safer smoking equipment. Between one third and half of respondents were interested in getting free safer smoking equipment, depending on the drug. A large number of participants reported that access did or would reduce their frequency of injection. Conclusions: The widespread change in drug use patterns and the higher-risk behavior associated with co-use nationally signal the need for swift, coordinated public health action to expand harm reduction and treatment services and to develop data-informed clinical guidelines to serve this growing population. Locally, methamphetamine-opioid co-use was influenced by complex personal, social, and societal factors. Public health policy to address the needs of people who co-use through treatment, harm reduction, and other social programs must support individuals, their communities, and the broader structural environment. Harm reduction strategies like provision of free safer smoking equipment may be an important tool to reduce risks from opioid and stimulant injection.