Opioid Overdose Mortality Among Patients Receiving a Peer-Delivered, Emergency Department–Based Nonfatal Opioid Overdose Intervention in New York City, 2017–2022

<b>Objectives.</b> To measure risk of fatal opioid overdose within 1 year of engagement with Relay's nonfatal overdose response initiative and characterize differences in demographics, substance use, and overdose risk factors by service engagement. <b>Methods.</b> We assessed the mortality status of 5006 patients who presented to Relay's partnered emergency departments (EDs) in New York City for a suspected nonfatal opioid overdose (2017-2022) and accepted peer-delivered overdose prevention services in the ED, grouped by agreement to and subsequent receipt of post-ED follow-up. <b>Results.</b> Compared with those declining follow-up, the risk of fatal overdose was not significantly higher among those consenting (adjusted hazard ratio [AHR] = 1.24; 95% confidence interval [CI] = 0.94, 1.65). Among those accepting follow-up, risk was lower for those who were reached (AHR = 0.64; 95% CI = 0.48, 0.84) compared with those who were not. <b>Conclusions.</b> Peer-delivered ED interventions such as Relay may be effective in reducing fatal overdose risk for individuals with fewer risk factors, and post-ED services are essential for those at higher risk. Approaches should be tailored to more effectively deliver post-ED services to this group. (<i>Am J Public Health</i>. 2026;116(1):113-123. https://doi.org/10.2105/AJPH.2025.308270).