A systematic review of macro-, meso, and micro-level harm reduction interventions addressing the U.S. opioid overdose epidemic.

BACKGROUND: This systematic review aimed to 1) identify the range of opioid harm reduction interventions implemented at macro-, meso-, and micro-levels in the United States, and 2) summarize the outcomes of these interventions. METHODS: We conducted a systematic review of academic literature published between 2011-2023 following PRISMA guidelines. Articles were excluded if they reported on research that was not specific to opioids, did not report the effects of an intervention, or focused on a medical treatment for opioid use disorder. Two coders independently extracted data and reconciled discrepancies prior to narrative synthesis. RESULTS: Of 6,198 articles initially identified, 36 met inclusion criteria across macro (n=7), meso (n=8), and micro (n=21) domains. Positive evidence for micro- and meso-level interventions is largely consistent, whereas evidence for macro-level interventions is mixed. Among micro- and meso-level interventions, supply distribution interventions were most effective in increasing safe use knowledge and behaviors among people who use drugs. DISCUSSION: Most harm reduction interventions demonstrate moderate to strong evidence of effectiveness for addressing the opioid overdose epidemic across domains. Findings revealed a lack of multi-level interventions and a lack of culturally relevant interventions that prioritize Black and Brown communities disproportionately impacted during the opioid overdose epidemic's latter phases.