A socio-ecological systematic review of harm reduction interventions addressing the U.S. opioid overdose epidemic

BackgroundOpioid-involved drug overdose deaths have skyrocketed over the past two decades,devastating the U.S. more than any other country. The U.S. opioid overdose epidemic has been particularly challenging to address because there have been four distinct, yet interconnected, phases of opioid-related mortality. Due to the complex nature of the epidemic, a range of interventions have been implemented across socio-ecological levels; however, little is known about the harm reduction (HR) interventions that have been implemented to address the U.S. opioid overdose epidemic. As such, this systematic review aimed to identify and summarize the range and outcomes of opioid-specific HR interventions implemented across macro, meso, and micro levels. MethodsWe conducted a systematic review of academic literature published between 2011-2023 following PRISMA guidelines. Five databases were systematically searched using an expert-informed search string. Articles that reported on research that was not specific to opioids, did not report the effects of an intervention, or focused on medical treatments for opioid use disorder were excluded. Risk of bias was assessed. The original search yielded 6,198 articles, which, upon deduplication, were entered into a software for title/abstract screening (n=2,850) and full-text review (n=96). Two coders independently extracted data and reconciled discrepancies prior to narrative and tabular synthesis. Results36 articles met inclusion criteria. 7 articles examined macro-level HR interventions (e.g., Good Samaritan Laws), 8 articles examined meso-level HR interventions (e.g., overdose education and naloxone distribution programs), and 21 articles examined micro-level HR interventions (e.g., fentanyl test strips programs). Evidence for micro- and meso-level HR interventions is largely consistent (i.e., interventions significantly associated with outcomes that reduce opioid-related harm), whereas evidence for macro-level interventions is mixed. Conclusions and ImplicationsFindings provide insight into the current state of scientific literature related to what HR interventions have been implemented and effective in addressing the U.S. opioid epidemic. The majority of included studies reported on micro-level interventions, revealing the U.S.’ emphasis on individual behavior change as opposed to social and structural change. Most included studies reported reaching White individuals, despite Black and Latinx communities being disproportionately impacted by the epidemic in recent years, suggesting the impact of historical racism and the presence of structural and institutional racism in HR service delivery. Findings highlight a lack of multi-level interventions and suggest a need for researchers to develop and examine HR interventions designed to impact multiple socio-ecological levels, which may produce synergistic effects and, therefore, greater benefits.