Employment and residential characteristics in relation to automated external defibrillator locations

Abstract

Background: Survival from out-of-hospital cardiac arrest (OHCA) is generally poor and varies by geography. Variability in automated external defibrillator (AED) locations may be a contributing factor. To inform optimal placement of AEDs, we investigated AED access in a major US city relative to demographic and employment characteristics.

Methods and results: This was a retrospective analysis of a Philadelphia AED registry (2,559 total AEDs). The 2010 US Census and the Local Employment Dynamics database by ZIP code was used. Automated external defibrillator access was calculated as the weighted areal percentage of each ZIP code covered by a 400-m radius around each AED. Of 47 ZIP codes, only 9% (4) were high-AED-service areas. In 26% (12) of ZIP codes, less than 35% of the area was covered by AED service areas. Higher-AED-access ZIP codes were more likely to have a moderately populated residential area (P = .032), higher median household income (P = .006), and higher paying jobs (P =. 008).

Conclusions: The locations of AEDs vary across specific ZIP codes; select residential and employment characteristics explain some variation. Further work on evaluating OHCA locations, AED use and availability, and OHCA outcomes could inform AED placement policies. Optimizing the placement of AEDs through this work may help to increase survival.

Figure 1

Percent of ZIP Code Area within AED Service Area. The vertical axis shows the percent of each ZIP code within a 400 meter radius service area of ZIP code AEDs. The horizontal axis is the number of ZIP codes.

Figure 2

Proportion of ZIP code within AED service area, 400 meter radius. Each dot represents an AED location. Darker areas represent a higher percent of the ZIP code within an AED service area.