Time-space characteristics of emergency medical service attendance and layperson naloxone administration during non-fatal opioid overdoses in Rhode Island: a retrospective, event-level analysis

As the opioid overdose crisis worsens in the United States (U.S.), emerging scholarship has uncovered time-and-place variations in substance use and overdose response efforts in community settings. Building on this work, we characterized spatio-temporal attributes of naloxone administration during non-fatal opioid overdoses attended by laypersons and emergency medical services (EMS) over a three-year period. Leveraging EMS encounter data across Rhode Island between January 2020 and December 2022, we quantified hour-by-hour variations in EMS deployment locations for non-fatal opioid-involved overdoses among adults (aged 18 + years). We used multivariable Poisson regression with robust standard errors to identify spatio-temporal patterns in EMS-attended overdoses by location type and evidence of layperson naloxone administration during these events. Of the 5377 EMS non-fatal opioid overdose encounters, most occurred in residential housing (61.1 %) and outdoor public spaces (19.3 %). We identified substantial time-space variations in non-fatal overdoses, with EMS deployments to residential housing clustering in non-daylight hours (5:00PM-8:59AM) and to outdoor public spaces in daylight hours (9:00AM-8:59PM). Documented naloxone intervention by laypersons prior to EMS arrival was uncommon (10.6 %) but was most pronounced in overdoses occurring in residential housing and the early afternoon (1:00PM-4:59PM). Despite the clustering of non-fatal opioid overdoses in housing environments, we identified substantial within-location variations in overdose-related EMS encounters over time and place.