Distribution, accessibility and coverage of auttomated external defibrillators in public locations in Hong Kong

Abstract

Introduction: The survival rate of out-of-hospital cardiac arrest (OHCA) in Hong Kong (HK) is low. Use of automated external defibrillators (AED) by the public can shorten the time to defibrillation and may improve survival. However, there is limited data on use of AED for OHCA in Hong Kong. This study aimed primarily at describing the distribution and accessibility of AEDs in HK and secondarily at the coverage rate of AED for OHCA using historical data. Methods: This was an observational descriptive study. Data for the AEDs were from the local AED distributors, the Heart-safe school project, government departments, NGOs and door-to-door search from 1/7/2015 to 31/12/2016. Data for OHCA were from a database maintained by the emergency medical services (EMS) during 1/8/2012 – 31/7/2013. Geographical locations of AEDs and OHCA were converted into Universal Transverse Mercator format. The Python 2.7 and R 3.2.5 were used to execute the GIS analysis and visualization. The distance between cardiac arrest and the closest AED was calculated. The proportion of historical OHCA occurring within 100m of an AED was calculated as coverage rate. Kruskal-Wallis test, Fisher exact chi square test, and t-test were used where appropriate. Results: In the study period, 1637 AEDs were located. The number of AEDs per 10,000 population and per km2 were 2.23 and 1.48. 49.4% (n=809) of the AEDs were placed in schools or educational institutions. 29.3% (n=479) were installed in recreational facilities supervised by the Government. Only 10.8% of these AEDs were accessible to the public without time restriction. Furthermore, only one third could be used by the public without the need for permission from personnel onsite. From the historical OHCA database, there were 5154 cases. 1.3% had bystander defibrillation. 30-day survival rate was 17.5% and it was much better than the 2.3% as a whole. The time to defibrillation when an AED was used by a bystander was shorter than by the EMS (6.8 min versus 15.2 min, p < 0.001). The coverage rate of an AED within 100m of cardiac arrest was 15.3%. The coverage rate in different districts of HK varied widely and it did not correlate with the survival rate in each district. Conclusion: Most AED in HK were placed in schools. Accessibility to the public is far from satisfactory. OHCA with bystander defibrillation had higher survival rate. AED coverage rate was low. More need to be done besides raising the coverage rate.