Abstract 138: Socioeconomically Equitable Public Defibrillator Placement Using Mathematical Optimization

Abstract

Introduction: Mathematical optimization can be used to place automated external defibrillators (AEDs) in locations that maximize coverage of out-of-hospital cardiac arrests (OHCAs). However, the extent to which optimization strategies affect socioeconomically equitable distribution of AEDs is unknown. Methods: All suspected OHCAs and registered AEDs in Scotland between Jan. 2011 - Sept. 2017 with a recorded location were included and mapped across the quintiles of the Scottish Index of Multiple Deprivation (SIMD), a national measure of socioeconomic status. First, we maintained AEDs at current locations and modeled placing an equal number of additional AEDs to maximize “coverage” (i.e., AED located within 100 m) of suspected OHCAs. A second analysis determined optimal sites for relocating all existing AEDs to optimize coverage without additional AEDs. We computed the proportion of OHCAs covered in each SIMD quintile under each AED placement strategy. A Wilcoxon signed-rank test was used to test difference in coverage levels across all regions of Scotland. Results: We identified 49,692 suspected OHCAs and 1,532 AEDs. Existing AEDs covered 1,384 OHCAs (2.8%), with OHCA coverage peaking in quintile 3 (moderate deprivation), indicating a mismatch with the distribution of suspected OHCA. Adding an equal number of new AEDs in optimal locations covered 10,465 OHCAs (21.1%; P<0.001). Optimal relocation of existing AEDs with no additional units covered 9,464 OHCAs (19.0%; P<0.001). OHCA coverage under either optimization strategy peaked in quintile 1 (highest deprivation), aligning to the OHCA incidence distribution. Conclusion: Optimizing AED placement significantly increases OHCA coverage and better aligns coverage with OHCA incidence across SIMD quintiles, improving socioeconomic equity of OHCA coverage. Relocating existing AEDs could achieve similar coverage to doubling the number of devices.