Spatial point pattern analysis of prehospital naloxone administrations

Objectives The increasing problem in the United States with opioid dependence and overdose, often fatal, is well-recognized. As naloxone has only one clinical use— the treatment of opioid overdose—its administration by EMS personnel can serve as a surveillance indicator for opioid overdose. This study uses specific locations of EMS calls, and methods of point pattern analysis, to detect overall spatial clustering among EMS naloxone administrations compared to EMS calls in general. Study Design A cross-sectional study of incident locations of EMS responses in a three-county EMS region in the United States. Methods Repeated random samples from the spatial distribution of all EMS calls were used, in a Monte Carlo simulation, to represent the background inhomogeneity of the population. Observed F, G, and inhomogeneous K and L functions from the spatial distribution of naloxone-involved calls were compared to their null sampling distributions obtained from the Monte Carlo simulation. Results Cases of naloxone administration demonstrated spatial clustering in the range of 0 to 5000 meters, and particularly around 2500 meters, beyond what could be attributable to the spatial heterogeneity of all EMS calls. Conclusions Efforts to understand the fundamental nature of opioid overdose as a spatial point process could yield innovative public health interventions to control the epidemic. 1 . CC-BY-NC-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/100412 doi: bioRxiv preprint first posted online Jan. 17, 2017;