Prevalence and correlates of multiple injections per injection episode among people who inject drugs in rural U.S. communities

Background: Multiple injections per injection episode (MIPIE) is increasingly common among people who inject drugs (PWID). While MIPIE may lower overdose risk, it could elevate infectious disease risk. This study examined the prevalence of MIPIE among rural PWID in the United States and its associations with injection behaviors associated with disease transmission (e.g., syringe mediated drug sharing, receptive supply sharing) and health outcomes (e.g., hepatitis C virus (HCV) status, naloxone possession, and overdose). Methods: The Rural Opioid Initiative includes eight research cohorts of rural people who use drugs from across the U.S., recruited from 01/2018 to 03/2020. MIPIE was dichotomized as any vs. none using the question: “How many times in the past 30 days did you inject more than one time in one sitting?” We employed a fixed effects meta-analytic approach to examine cross-sectional associations through adjusted regression analyses. Results: Among 2441 PWID, most reported MIPIE (71% [n=1729]). In adjusted analyses, MIPIE was associated with a higher prevalence of past 30-day receptive syringe sharing (Prevalence Ratio (PR)=2.02; 95% confidence interval (CI)=1.74–2.34), syringe-mediated drug sharing (PR=1.92; 95%CI=1.69–2.18), receptive supply sharing (PR=1.99; 95%CI=1.75–2.26), distributive supply sharing (PR=2.30; 95%CI=1.99–2.65), HCV (PR=1.26; 95%CI=1.11–1.44), naloxone possession (PR=1.32; 95%CI=1.17–1.50), overdose ever (PR=1.42; 95%CI=1.25-1.57), and overdose in the prior 90 days (PR=2.09; 95%CI=1.52–2.87). Conclusions: MIPIE is a common practice among rural PWID and is associated with injection behaviors associated with disease transmission, HCV, and overdose. Intervention studies should develop harm reduction strategies that address both overdose prevention and infectious disease mitigation related to MIPIE.