Syringe Service Program Utilization, Behavioral, and Experiential Factors Associated with Greater Naloxone Protection in a Longitudinal Cohort of People Who Use Illicit Opioids in New York City

Background Despite efforts to blanket high-mortality communities with no-cost naloxone, drug checking technologies, and alternatives to using opioids alone, there remains a considerable lack of knowledge about how exposure to these low-threshold interventions may impact rates of naloxone protection. Methods People who used illicit opioids in New York City were surveyed between April 2019–April 2022. Naloxone protection was defined as the proportion of opioid use events in the past 30 days when opioid use occurred with naloxone present and someone to administer it. Mixed-effect Poisson models examined correlates (syringe service program utilization, behavioral, and experiential factors) of naloxone protection among the overall sample and stratified by gender. Results Among 428 study participants (mean age 49 years, 64% cisgender male, 35% Black, 41% Latinx), several factors were significantly associated with naloxone protection levels. Visiting a syringe service program (SSP) in the last three months was significantly associated with higher naloxone protection in the full sample (IRR = 1.94, 95% CI: 1.38–2.74) and among males (IRR = 1.84, 95% CI: 1.29–2.64). Significantly lower naloxone protection was also observed among Latinx participants compared to White individuals in the full sample (IRR = 0.64, 95% CI: 0.44–0.94) and among females aged 57–72 years compared to those aged 20–40 years (IRR = 0.39, 95% CI: 0.16–0.95). Participants living with someone who does not use opioids (vs. living with someone who uses opioids) showed significantly lower naloxone protection levels in the full sample (IRR = 0.54, 95% CI: 0.37–0.80) and among males (IRR = 0.46, 95% CI: 0.29–0.73). Other factors associated with lower naloxone protection in the full sample included any opioid withdrawal in the last 30 days, higher pain severity, and more negative life events. Conversely, receiving social support from another person who uses opioids was significantly associated with higher naloxone protection in the full sample (IRR = 1.14, 95% CI: 1.07–1.22) and among females (IRR = 1.30 95% CI 1.16–1.46). Additional factors associated with greater naloxone protection in the full sample included: concurrent opioid and stimulant use, heroin/injection use (1–15 days), fentanyl test strip use, lifetime opioid overdose, and number of lifetime arrests. Conclusion Findings suggest positive impacts of syringe service program engagement and use of harm reduction best-practices and interventions on promoting naloxone protection and highlight differential associations. These results can be used to inform culturally-sensitive and tailored outreach to people at risk of overdose.