Out-of-hospital cardiac arrest (OHCA) is one of the leading causes of death, and it is regarded as an important public health issue [1-3]. Developed countries have established community response systems for OHCA, achieving remarkable improvement, but OHCA outcomes still vary greatly among cities and countries [1,4].

South Korea has recently shown increased interest in OHCA, making efforts to improve its survival rate. For example, the Korean Center for Disease Control and Prevention launched a Cardiovascular Disease Surveillance project to collect OHCA data in South Korea [5]. While this database provides a national picture of the state of OHCA, the information it contains is insufficient for a detailed understanding of OHCA in specific communities.

Effective responses to OHCA require emergency medical services (EMS), hospitals, and the public to integrate care and continually monitor interventions [6,7]. To work toward this ideal response, healthcare organizations must first understand the current state of OHCA treatment in their community. This study aimed to assess the state of OHCA treatment in Ansan City by analyzing the OHCA incidence, processes of care, and outcomes in Ansan City. Our analysis of this information provides a baseline from which this community can work toward improved OHCA outcomes. To our knowledge, this is the first study in South Korea to describe in detail a regional community’s response to OHCA.

During the study period, the total number of EMS-assessed OHCA patients was 1,218, and resuscitation was attempted in 1,083 cases. After excluding cases involving trauma, drowning, asphyxia, and arrests that occurred after EMS arrival, we analyzed 778 adult OHCA cases. The adjusted incidence of OHCA was approximately 33.1/100,000 persons per year. The mean age of the patients was 64.9±18.2 years. There were 458 male patients (58.9%) and 320 female patients (41.1%) (Table 1). The core data elements of OHCAs in Ansan City are displayed in Fig. 1 according to the Utstein reporting template.

Overall, 31/778 patients (4%) survived to discharge during the study period. Neurological outcomes were confirmed in 21/31 (67.7%) discharged patients: 6/31 (19.4%) had a favorable neurological outcome (CPC score of 1 or 2) and 12/31 (38.7%) had a poor neurological outcome (CPC score of 4).

Despite numerous large-scale training efforts and multiple iterations of guidelines, OHCA remains a leading cause of death and a major public health problem in the industrialized world [1-3]. Survival is very low in most jurisdictions, and there are large variations in survival rates. Such variability is presumably related to the extent to which important interventions are implemented; immediate recognition of cardiac arrest, early CPR with an emphasis on chest compressions, rapid defibrillation, effective advanced life support, and integrated postcardiac arrest care are all believed to improve survival rates [1,4,6,10]. The American Heart Association refers to these aspects of the OHCA response as the chain of survival [6]. Strengthening this chain requires setting and meeting standards for implementing these interventions in EMS systems, hospitals, and the public [6,7].

In Korea, various efforts have been made to determine OHCA incidence and survival rates [5,11]. To our knowledge, however, this is the first study to report on the incidence, processes of care, and outcomes from OHCA in a specific regional community in Korea using the standardized Utstein template [9]. Accurate and on-going measurement is believed to be a fundamental component of any system of resuscitation care [6]. It is essential, therefore, to have not only national but also regional OHCA data in order to measure and track incidence, individual interventions, and the overall effectiveness of response systems. While we found the overall OHCA survival rate in Ansan City to be very low (4%, with 6/778 [0.8%] having a good neurological outcome), our results are similar to those previously published in Korea and significantly lower than results found in many reports from Europe, North America, and Japan [1,4,10] We believe that while the survival rates we found were low, this report is a key step in the process of improving outcomes from OHCAs in Ansan City. Accurately measuring incidence, processes, and outcomes will guide the standards of care by showing whether specific interventions are improving, having no impact or even lowering survival rates.

The chain of survival, composed of early recognition and EMS activation, early bystander CPR, rapid defibrillation, effective advanced life support and integrated postcardiac arrest care is important for enhancing the OHCA survival rate [6]. Our study suggests that in Ansan City there are several links in the chain of survival that need to be strengthened. Of the 778 adult OHCA cases of presumed cardiac etiology, 295/778 (37.9%) were witnessed by first responders, and this result was not significantly different from that of previous studies [4,10]. Nevertheless, only 103/778 (13.2%) received bystander CPR, a rate significantly lower than those reported in other studies [4,10-13]. Considering the large impact bystander CPR has on survival [12-15], this deficit likely contributes to Ansan City’s very low survival rate. One of our strategies going forward will be to target large-scale public and dispatch CPR education, training, and outreach aimed at improving bystander CPR. Of the 103 cases in which patients received bystander CPR, CPR instructions were given by dispatchers in 57/103 cases (55.3%). As shown in Table 2, when lay rescuers were provided with CPR instructions by dispatch personnel, the rate of bystander CPR was significantly higher than the rate without instructions (51.4% vs. 6.9%, P<0.001). This finding suggests that dispatcher guidance is effective in increasing the incidence of prearrival CPR. Prearrival CPR instruction, in fact, has been suggested as a cost-effective strategy for increasing bystander CPR rates and OHCA survival [16-18]. Of the 778 OHCA cases in our study, EMS personnel provided CPR instructions only in 111 cases (14.3%). This finding reveals a clear opportunity for system improvement, especially since Ansan City has no standardized protocol for dispatcher-guided bystander CPR instruction. Another important strategy, then, will be to implement a 1-1-9 training program that focuses on instructing dispatchers to recognize cardiac arrest and instruct callers on how to perform chest compressions.

Rapid defibrillation has been shown to improve the likelihood of good outcomes following OHCA [6,7]. In our study, the rate of trained EMS rescuer defibrillation for patients who required it was only 27.1%. Our data suggest that EMS providers should receive more complete training with an emphasis on identification of ventricular dysrhythmias and the need for immediate defibrillation.

In its 2010 guidelines, the American Heart Association added integrated postcardiac arrest care to the chain of survival [6]. Appropriate postcardiac arrest care, including, when indicated, mild therapeutic hypothermia or percutaneous coronary intervention, is believed to be critical for obtaining good outcomes from OHCA [19-21]. Our results showed that mild therapeutic hypothermia and coronary angiocardiography were performed infrequently during in-hospital postcardiac arrest care in the 3 medical institutions that treated more than 100 OHCA patients during the study period. While Ansan City hospitals already have standard guidelines for in-hospital postcardiac arrest care, our findings indicate that these are not being followed. Emergency care facilities in Ansan city need prompt education and continuing assessment and feedback to reinforce the importance of these postarrest procedures. Of the 12 medical institutions in Ansan City that accept cardiac arrest patients, 7 received fewer than 50 cardiac arrest patients in 4 years. Considering the human resources, equipment and facilities available at these low-volume institutions, integrated postcardiac arrest care may require the creation of a regional community plan for patient transportation after ROSC [22,23].

This study has several limitations. We retrospectively reviewed all of the available EMS and hospital data using the Utstein style of reporting, but it is possible that our data capture was incomplete, and there may have been some ascertainment bias with regard to the determination of arrest etiology. It is also possible that EMS and hospital databases contained erroneous information. Differences in the style and integrity of medical records among the 12 hospitals studied might have affected the accuracy of hospital data collection. Furthermore, our study of the survival group was limited, as the total number of patients and the number of patients who survived until discharge was small. More standardized electronic data collection may, in the future, help overcome such limitations.

In summary, our analysis of the incidence, processes of care and outcomes of OHCA in Ansan City, Korea, showed its survival rate to be very low. This is likely related to multiple variables within the chain of survival, several of which are modifiable. Our results identified key areas for improvement, a first step necessary in increasing OHCA survival in Ansan City. Our findings should prompt the Ansan City medical and public policy communities to join together, creating a comprehensive plan for an effective, integrated resuscitation system that will strengthen the OHCA chain of survival in Ansan City.