Discussion

Although the effectiveness of the PAD program has been confirmed several times, ^{Reference Nakashima, Noguchi and Tahara6–Reference Hallstrom, Ornato and Weisfeldt11} to the best of the authors’ knowledge, the present study is the first to investigate the current status and effectiveness of placement and usage of AEDs in South Korea. In a systematic review, the median survival to hospital discharge ratio when PAD was performed by lay persons after OHCA was 53%. ^{Reference Baekgaard, Viereck, Moller, Ersboll, Lippert and Folke12} Therefore, proper placement of AEDs throughout the nation is essential for the success of the PAD program.

The current study confirmed that the number of installed AEDs in South Korea increased rapidly after two important laws (the law on AEDs and the Good Samaritan Law) came into effect. The strategy of using laws to establish a PAD program has been effective in increasing the absolute number of installed AEDs in South Korea. However, the current study discovered several problems.

First, there were mismatches between the number of installed AEDs and the annual rate of AED use among provinces and places. For example, there was an extremely low rate of AED use in Gyeonggi-do, where a large number of AEDs were installed in apartment complexes (4,472 [58.6%]). The annual rate of AED use in apartment complexes was extremely low. Consequently, the overall annual rate of AED use in Gyeonggi-do decreased. Although the Act dictated installation of AEDs in apartment complexes with ≥500 households, the Act did not propose a minimum number of AEDs. Therefore, some apartment complexes installed an AED in every building, and others installed AEDs in only one or two buildings, especially in the control office. This inconsistent strategy contributed to a different distribution of AEDs in provinces. In contrast, in Jeju Province, only 15 (1.2%) AEDs were installed in apartment complexes.

Second, there was an excess number of AEDs installed in residential areas (31.3% of all AEDs). In Japan ¹³ and Copenhagen, ^{Reference Folke, Lippert and Nielsen14} the percent of AEDs installed in public areas was 82.4% and 94.2%, respectively. Although 60%-80% of cardiac arrest occurs at home, the effectiveness of AEDs was low in residential areas because of fewer witnessed arrests, lower bystander cardiopulmonary resuscitation rate, and fewer shockable rhythms than that in public areas. ^{Reference Perkins, Handley and Koster1,Reference Weisfeldt, Everson-Stewart and Sitlani15} In addition, several studies reported that there were no advantages when AEDs were applied in residential area, even in the home of high-risk patients. ^{Reference Kiguchi, Kiyohara and Kitamura16,Reference Bardy, Lee and Mark17} On the contrary, many studies showed a survival benefit of AED in public areas. ^{Reference Hallstrom, Ornato and Weisfeldt11,Reference Weisfeldt, Everson-Stewart and Sitlani15,Reference Kiguchi, Kiyohara and Kitamura16} Therefore, a redistribution of AEDs in South Korea is needed to maximize their effectiveness.

Third, because the Act requires installation of AEDs on ships when the tonnage is ≥20 tons, an excess number of AEDs were installed on ships. However, the annual rate of AED use on ships was only 0.15%. As a result, in South Korea, 16,007 (43.9%) AEDs were placed in areas with low usage, such as apartment complexes and ships.

Fourth, there was a mismatch in the number of installed AEDs and the annual rate of AED use between places for which installation was required by the Act and places for which installation was not required. Although the number of AEDs in required places was larger than that of non-required places, the annual rate of AED use was significantly higher in non-required places. This result suggests that places designated by the Act are not as effective.

Placement of AEDs without guidance or evidence regarding effectiveness can result in ineffective installation. ^{Reference Folke, Lippert and Nielsen14,Reference Nichol, Huszti and Birnbaum18} Muraoka, et al recommended six locations for installation, including workplaces, railway stations, hospitals, homes for the aged, other playgrounds, and golf courses, considering the incidence of cardiac arrest, the ratio of ventricular fibrillation, and good neurological outcomes. ^{Reference Muraoka, Ohishi and Hazui19} Several places in the current study showed a higher annual rate of AED use, such as sanatoria, banks, subway stations, civilian medical facilities, senior centers, other playgrounds, resorts, other multi-housing facilities, and swimming pools. Among these, only other multi-housing facilities (comprising housing facilities, including those for individuals who are homeless or disabled) were classified as residential areas. Accordingly, the annual rate of AED use was higher than that of apartment complexes. With the exception of sanatoria and civilian medical facilities, all places were classified as public areas. Patterns regarding the time of AED use also showed that most PAD is delivered in the daytime. Overall, previous evidence and present data show that AEDs should be placed in public places where there is a higher probability of a witnessed cardiac arrest during the day. ^{Reference Brady, Mattu and Slovis3}