PHWR Public Health Weekly Report

Sudden cardiac arrest (SCA) refers to the abrupt cessation of cardiac function due to any cause, which leads to hemodynamic instability and can result in multiorgan damage and death. The survival rate after SCA is low, and without prompt and appropriate medical intervention, even survivors may suffer from sequelae, leading to significant economic and social implications. Therefore, prevention of circulatory collapse through immediate and appropriate cardiopulmonary resuscitation (CPR), rapid transport to the emergency room (ER), and proper treatment and procedures in the ER and hospital are of utmost importance. The survival of patients with out-of-hospital cardiac arrest (OHCA), in particular, is often used as a metric for evaluating a nation’s emergency medical system [1]. According to the Out-of-Hospital Cardiac Arrest Surveillance from the Korea Disease Control and Prevention Agency (KDCA), the following changes have been observed in key indicators over the last 5 years. The incidence of OHCA per 100,000 population increased from 60.0 in 2019 to 65.7 in 2023, although the survival rate remained similar, only changing from 8.7% in 2019 to 8.6% in 2023. However, because the survival rate hovered between 7.0% and 8.0% from 2020 to 2022, the 2023 figure suggested partial recovery. The neurological recovery rate also showed a slight increase from 5.4% in 2019 to 5.6% in 2023, indicating a gradual improvement in prognosis. While indicators such as the survival rate, neurological recovery rate, and bystander CPR rate have been improving (excluding the incidence of OHCA), there are disparities among different regions [2].

The aim of this investigation was to analyze the differences in OHCA-related indicators between the nation as a whole and the cities and provinces of the Chungcheong region using the recently released 2023 Out-of-Hospital Cardiac Arrest Surveillance. The Chungcheong region is divided into four administrative districts: Daejeon, Sejong, Chungcheongnam-do (Chungnam), and Chungcheongbuk-do (Chungbuk). Although its aging index is relatively low, the region is characterized by distinct geographic concentrations of elderly and younger populations [3]. As a reflection of these characteristics, there are disparities in the rate of aging, health-related indicators, and the prevalence of chronic diseases among the different areas [4]. Furthermore, a shortage of hospitals has been reported in parts of the Chungnam area [3], and according to the Chungcheong Community Health Survey, the rate of unmet medical needs in the cities and provinces of the Chungcheong region increased from 2022 to 2023; this indicated issues related to the demand and distribution of healthcare resources [5]. On the basis of such studies, the Chungcheong Regional Center for Disease Control and Prevention has been making various efforts to address health issues tailored to the Chungcheong region. The findings of this study are expected to provide foundational data for establishing OHCA prevention management strategies that consider the specific characteristics of the Chungcheong region. They may also serve as meaningful data for other cities, provinces, and districts with regional characteristics similar to those of the Chungcheong region.

1. Study Population

This study used raw data from the 2019–2023 medical record surveys that were a part of Out-of-Hospital Cardiac Arrest Surveillance (National Statistics Approval No. 117088) conducted by the KDCA under Article 6 of the Act on the Prevention and Management of Cardiovascular Diseases (Approval No. KDCA-12-02-CA-2025-0001118). The primary data from the 2023 Out-of-Hospital Cardiac Arrest Surveillance were collected from August 2023 to July 2024. From 33,586 patients transported by 119 emergency services nationwide, 33,402 individuals with complete medical records were analyzed. From these individuals, 4,260 were from the Chungcheong region, including 792 from Daejeon, 158 from Sejong, 1,451 from Chungbuk, and 1,859 from Chungnam.

2. Variable Selection and Analysis

To compare the incidence and prognosis of OHCA in the cities and provinces of the Chungcheong region with the national average, the incidence rate, survival rate, and neurological recovery rate were analyzed for both the nation and the Chungcheong region. The OHCA incidence rate was calculated from the number of OHCA patients transported to hospitals by 119 emergency services and the mid-year resident registration population for the corresponding year [2]. Survival was defined as discharge from the ER, discharge after admission, discharge against medical advice, or transfer to another facility [6]. The neurological recovery rate referred to the proportion of OHCA patients who achieved a favorable neurological outcome [2], which was defined as a cerebral performance category scale score of 1 or 2 upon discharge in this study [7]. In addition, factors that could influence the prognosis of OHCA were identified through a review of previous studies [1]. While rapid and precise medical intervention is critical for a good prognosis in OHCA, prehospital factors also affect outcomes [1]. For this study, we selected variables that could be monitored and potentially modified at the community public health level. These variables included sex, age, witnessed arrest status, bystander CPR provision, cause of OHCA, past medical history (hypertension, heart disease, kidney disease, stroke, dyslipidemia), and time from OHCA onset to ER arrival [1]. The time to ER arrival was calculated as the interval between the time at which OHCA was witnessed and the time of ER arrival [1,6]. The cause of OHCA was categorized as disease-related factors or non disease-related factors, with the latter including unknown causes. The time to ER arrival was categorized as <8, 8–11, 12–19, 20–39, and ≥40 minutes.

The data were analyzed using descriptive statistics in Microsoft Excel 2021 (Microsoft) and are presented as frequencies and percentages (%).

1. Incidence of OHCA by City and Province in the Chungcheong Region

Examination of the OHCA incidence over the past 5 years (2019–2023) showed a slight increase from 2020 to 2022, followed by a decreasing trend in 2023 (Figure 1A). In 2023, 119 emergency services transported 33,586 OHCA patients nationwide, with 4,268 (12.7%) being in the Chungcheong region [2]. When converted to an incidence rate per 100,000 population, the national average was 65.7 cases. The rates in Sejong (41.1 cases) and Daejeon (55.1 cases) were lower than the national average, while the rates in Chungbuk (91.4 cases) and Chungnam (87.9 cases) were higher. Notably, Chungbuk had the third-highest incidence rate, following Jeju (95.1 cases) and Gangwon (94.4 cases) (Figure 1B). Within the Chungcheong region, the difference between the highest (Chungbuk) and lowest (Sejong) incidence rates was 50.3 cases, indicating a larger intraregional disparity than that in other provinces nationwide.

Figure 1. Trends in OHCA incidence per 100,000 population in the Chungcheong region
(A) Annual incidence. (B) Regional differences in incidence based on 2023 data.
OHCA=out-of-hospital cardiac arrest.

2. Survival and Neurological Recovery Rates of OHCA Patients by City and Province in the Chungcheong Region

As of 2023, the national survival rate for OHCA patients was 8.6%. Within the Chungcheong region, the rates in Daejeon (7.7%), Chungnam (7.7%), and Chungbuk (7.9%) were lower than the national average, while the rate in Sejong (14.6%) was higher than that in other areas in the region (Figure 2A).

Figure 2. Trends in characteristics related to survival over the past five years (2019–2023)
(A) Survival rate: discharge alive. (B) Neurological recovery rate: brain function recovered enough to enable daily life.
^a)Data not presented for categories with fewer than 10 cases.

The national neurological recovery rate for OHCA patients was 5.6%; in the Chungcheong region, the rates were 5.4% in Daejeon, 4.9% in Chungbuk, and 5.2% in Chungnam. Similar to its high survival rate, Sejong showed a high neurological recovery rate of 13.3%, exceeding the average in other areas (Figure 2B).

3. General Characteristics of OHCA Patients by City and Province in the Chungcheong Region

The general characteristics of patients with OHCA in 2023 were analyzed (Table 1). The incidence of OHCA was higher for male than for female individuals and increased with age, a pattern that was similar both nationwide and within the cities and provinces of the Chungcheong region. However, there were regional differences in the age distribution of OHCA patients. The proportion of elderly patients aged ≥80 years in Daejeon and Sejong was comparable to or lower than the national average, whereas in Chungbuk and Chungnam, this proportion was 33.8% and 37.5%, respectively, being higher than the national average by 1–5%p.

Table 1 Chungcheong regional demographic and characteristics of OHCA patients in 2023

Variable	Overall (n=33,402)	Daejeon (n=792)	Sejong (n=158)	Chungbuk (n=1,451)	Chungnam (n=1,859)
Sex
Male	21,485 (64.3)	479 (60.5)	101 (63.9)	918 (63.3)	1,174 (63.2)
Female	11,917 (35.7)	313 (39.5)	57 (36.1)	533 (36.7)	685 (36.8)
Age (yr)
<20	680 (2.0)	13 (1.6)	7 (4.4)	30 (2.1)	42 (2.3)
20–39	2,004 (6.0)	62 (7.8)	6 (3.8)	103 (7.1)	87 (4.7)
40–59	6,631 (19.9)	141 (17.8)	29 (18.4)	266 (18.3)	342 (18.4)
60–79	13,386 (40.1)	316 (39.9)	70 (44.3)	561 (38.7)	690 (37.1)
≥80	10,701 (32.0)	260 (32.8)	46 (29.1)	491 (33.8)	698 (37.5)
Past history
Hypertension	11,284 (33.8)	312 (39.4)	64 (40.5)	450 (31.0)	632 (34.0)
Diabetes mellitus	7,765 (23.2)	200 (25.3)	35 (22.2)	301 (20.7)	440 (23.7)
Heart disease	5,510 (16.5)	154 (19.4)	35 (22.2)	219 (15.1)	274 (14.7)
Renal disease	2,110 (6.3)	64 (8.1)	11 (7.0)	84 (5.8)	89 (4.8)
Pulmonary disease	1,924 (5.8)	47 (5.9)	9 (5.7)	82 (5.7)	94 (5.1)
Stroke	2,531 (7.6)	56 (7.1)	11 (7.0)	98 (6.8)	124 (6.7)
Dyslipidemia	2,228 (6.7)	50 (6.3)	11 (7.0)	99 (6.8)	103 (5.5)
Causea)
Disease	25,604 (76.7)	636 (80.3)	123 (77.8)	1,124 (77.5)	1,417 (76.2)
Non disease	7,798 (23.3)	156 (19.7)	35 (22.2)	327 (22.5)	442 (23.8)
Witnessb)
Yes	18,133 (54.3)	477 (60.2)	102 (64.6)	855 (58.9)	1,116 (60.0)
No	15,269 (45.7)	315 (39.8)	56 (35.4)	596 (41.1)	743 (40.0)
Bystander CPRc)
Yes	9,068 (31.3)	236 (33.9)	52 (39.1)	426 (33.8)	293 (18.1)
Time from onset of the cardiac arrest to ER arrive (min)d)
<8	826 (4.8)	21 (4.5)	8 (7.8)	36 (4.4)	46 (4.3)
8–11	549 (3.2)	13 (2.8)	2 (2.0)	27 (3.3)	37 (3.5)
12–19	1,539 (9.0)	32 (6.9)	5 (4.9)	84 (10.3)	66 (6.2)
20–39	9,795 (57.0)	314 (67.2)	51 (50.0)	424 (52.0)	533 (50.2)
≥40	4,484 (26.1)	87 (18.6)	36 (35.3)	245 (30.0)	379 (35.7)

Unit: number (%). OHCA=out-of-hospital cardiac arrest; CPR=cardiopulmonary resuscitation; ER=emergency room; ^a)OHCA etiology was categorized as disease-related or non-disease-related; the latter includes unknown causes. ^b)“Witnessed” indicates the arrest was seen; “No” includes unknown cases. ^c)Bystander CPR refers to CPR performed by laypersons, excluding on-duty healthcare providers. ^d)Based on cases with documented time intervals between the witnessed cardiac arrest and arrival at the emergency department in medical records..

Regarding the past medical history of OHCA patients, hypertension, diabetes, and heart disease, in that order, were the most common; this pattern was consistent with national data. Furthermore, in both the nation and the Chungcheong region, over 70% OHCA were due to disease-related factors, the majority of which were of cardiac origin.

Whether an OHCA is witnessed is an important factor that can influence the survival rate [2,8]. In 2023, the national rate of witnessed OHCA was 54.3%. In the Chungcheong region, the rates were higher than the national average: 60.2% in Daejeon, 64.6% in Sejong, 58.9% in Chungbuk, and 60.0% in Chungnam.

The bystander CPR rate, excluding CPR performed by healthcare professionals or on-duty emergency medical technicians, was 31.3% nationwide. Regional variations were observed, with a rate of 33.9% in Daejeon, 39.1% in Sejong, 33.8% in Chungbuk, and 18.1% in Chungnam.

In both the nation and the Chungcheong region, ≥80% cases showed an interval of ≥20 minutes between the time at which OHCA was witnessed and ER arrival.

SCA refers to the sudden cessation of cardiac function due to factors such as disease and injury. As the time from cardiac arrest to intervention such as CPR increased, the survival and neurological recovery rates decrease. Therefore, a rapid intervention to SCA is essential [1].

In 2023, 33,586 patients were transported to hospitals for OHCA. For individuals with complete medical records, an analysis of the incidence rate per 100,000 population showed that Daejeon and Sejong had lower rates than the national average, whereas Chungbuk and Chungnam had higher rates. This can be understood in the context of previous research indicating that differences in age distribution within the Chungcheong region lead to disparities in key health-related indicators [3].

Nationwide, 72.1% OHCA patients were aged ≥60 years. In the Chungcheong region as well, this proportion was >70% in all cities and provinces: 72.7% in Daejeon, 73.4% in Sejong, 72.5% in Chungbuk, and 74.6% in Chungnam. Furthermore, in Daejeon, Chungbuk, and Chungnam, the proportion of OHCA patients aged ≥80 years exceeded 30%. Considering the pace of population aging in the Republic of Korea, the proportion of elderly individuals among OHCA patients is expected to increase further, thus affecting patient survival and neurological recovery rates. In Chungnam and Chungbuk, which had a relatively higher proportion of OHCA patients aged ≥80 years than did Daejeon and Sejong, the incidence rate was high while the survival and neurological recovery rates were low. This suggests that aging is a factor that influences not only incidence but also prognosis. The fact that prognosis worsens with increasing age has been discussed in many studies [6,7,9]. This is because physiological resilience decreases while comorbidities increase; furthermore, with advancing age, treatment options for OHCA may become limited [7]. Thus, strategies to address OHCA in the elderly population probably differ from those for other age groups, and regions with a high proportion of elderly residents must develop plans that take this into account.

The survival and neurological recovery rates for OHCA patients are important indicators to evaluate the propriety of the provided medical interventions [8]. During the coronavirus disease 2019 (COVID-19) pandemic in 2020 and 2021, the incidence increased while the survival rate decreased. However, by 2023, survival and neurological recovery rates across the nation, including the Chungcheong region, had recovered to pre-COVID-19 levels [2,10]. The neurological recovery rate, a determinant of post-survival quality of life among OHCA patients, shows a trend similar to that shown by the survival rate. Although the absolute number of OHCA events in Sejong was lower than that in other areas in the Chungcheong region, the survival and neurological recovery rates were higher than both the regional and national averages. The higher-than-average neurological recovery rate in Sejong can be explained by a combination of factors, including the lower proportion of elderly OHCA patients compared to that in other areas in the region as well as the high witnessed arrest and bystander CPR rates. These findings are consistent with those in studies on post-OHCA prognosis [1,6,9].

As mentioned above, various factors collectively influence the recovery of OHCA patients. In particular, if OHCA is witnessed, the survival rate increases by more than three-fold [2] because witnessed OHCA is associated with rapid initiation of CPR and prompt transport to the ER. Compared with the national average, the witnessed arrest rates in Daejeon, Sejong, Chungbuk, and Chungnam were all high. In particular, the witnessed arrest rate in Sejong was 64.6%, ≥10%p higher than the national average, while that in the other areas was also 4–10%p higher than the national average. The correlation between higher witnessed arrest rates and increased survival is a common finding in many studies [2,10,11]. Witnessed OHCA is closely associated with the location of the event, and its likelihood tends to decrease for older individuals and for individuals with arrests occurring at home [10,11]. With aging and nuclearization of families in many countries, the proportion of single-person households is increasing along with that of households comprising single elderly individuals or elderly couples. Consequently, a decline in the witnessed arrest rate is an inevitable outcome when OHCA occurs in these settings. Therefore, in regions with a high proportion of elderly residents, community surveillance systems should be enhanced by establishing monitoring systems involving the use of wearable devices for high-risk groups [10]. In the Chungcheong region, projects have been implemented to reduce health disparities by selecting areas with significant gaps according to the results of the Community Health Survey. These community-based projects have included not only direct education of residents but also training programs for community health leaders. Incorporation of content regarding monitoring of OHCA among high-risk individuals within these training programs could be an effective strategy.

CPR performed by a bystander before the arrival of 119 emergency services is crucial for the patient’s survival and neurological recovery rates [12]. The importance of the witnessed arrest rate, as previously discussed, also stems from the fact that it increases the likelihood of rapid CPR initiation. In Sejong, the bystander CPR rate was high at 39.1% relative to that in other areas, whereas in Chungnam, it was low at 18.1%. While various factors can influence CPR provision, the issue of population aging must be examined first. According to a 2023 Statistics Korea survey, the proportion of individuals aged ≥65 years was 19.1% nationwide, 16.9% in Daejeon, 10.7% in Sejong, 20.6% in Chungbuk, and 21.1% in Chungnam. For the super-aged population (≥85 years), the proportions were 2.0% nationwide, 1.7% in Daejeon, 1.1% in Sejong, 2.4% in Chungbuk, and 2.9% in Chungnam. This indicates that Chungnam’s elderly population ratio is higher than the national average and that in other areas in the Chungcheong region [13]. Age can influence the effectiveness of CPR training. The importance of CPR training is well-established, as evidenced by the finding that a 10% increase in community CPR training experience is associated with a 1.4-fold increase in OHCA patient survival [14]. However, merely conducting protocol-based training may not yield the expected results. A trend of decreasing CPR training experience with increasing age has already been confirmed in a previous study [9], and this trend can also be observed in the age-specific CPR training status within the Chungcheong region, according to data from the 2022 and 2024 Community Health Surveys. Although the overall rate of CPR training experience increased in all four cities and provinces of the Chungcheong region, a marked decrease in the experience rate can be seen with increasing age [15]. Thus, it is necessary to explore ways to promote CPR education for the elderly. However, as the CPR training rate for those aged ≥60 years in Chungnam increased by more than 1.5-fold from 2022 to 2024, it will be necessary to monitor the bystander CPR rate in Chungnam in the post-2024 Out-of-Hospital Cardiac Arrest Surveillance in order to evaluate the effectiveness of this training [15]. For CPR training to translate into successful bystander CPR, factors such as awareness of CPR, hands-on experience through training, and a sense of self-efficacy for performing CPR have been shown to be influential [14]. As of 2022, the CPR awareness rate was ≥90% in most districts and across all age groups [15]. Therefore, the focus should be on an increase in CPR training to boost self-efficacy. In particular, when providing CPR-related education to the elderly, it is necessary to simplify the content to focus on speed and accuracy. As current guidelines already encourage chest compressions, which are relatively easy, after calling 119 in an OHCA event [11], it is important to increase self-efficacy for CPR through educational campaigns.

Finally, the time from witnessed arrest to ER arrival is another factor that can influence prognosis [1]. In this investigation, the proportion of cases with a time to ER arrival of ≥20 minutes was 83.1% nationwide, 85.8% in Daejeon, 85.3% in Sejong, 82.0% in Chungbuk, and 85.9% in Chungnam. The interval between the time at which OHCA is witnessed and ER transport has already been cited as a critical factor for survival and neurological recovery rates in various previous studies [1,3,4,6]. In particular, Kim and Chun [9] reported that the survival rate decreases by approximately 50% when this interval exceeds 32 minutes; this signifies the need for improvement in the current provision of emergency medical services. For OHCA, the importance of the golden time is extremely high, and it is closely related to the response of the community healthcare system [16]. Because it is often caused by an underlying disease, its risk is, to some extent, predictable [17]. Establishment of an emergency medical services system that can adequately respond to OHCA cannot be achieved simply by increasing the number of hospitals. It is a complex problem that requires consideration of regional supply and demand, traffic conditions, and distribution [18]. According to a study by Kim et al. [18] comprehensive consideration of demographic characteristics, environmental factors, and the availability of medical services is necessary when building an emergency medical services system. The authors suggested that deployment of even a small number of dispatchable emergency response bases in rural and fishing villages could significantly improve access to emergency care.

In conclusion, the present study confirmed the status of OHCA among residents of the Chungcheong region, examined various factors that could affect survival and neurological recovery rates, and considered the main factors influencing OHCA from three perspectives. First, the trend of increasing OHCA incidence and worsening prognosis with advancing age is commonly reported in numerous studies; this calls for the establishment of a response system tailored to the characteristics of an aging population. In particular, it is necessary to build a system for early screening and monitoring of high-risk groups with risk factors for OHCA at the community level. Furthermore, because the receptivity to and effectiveness of CPR education and campaigns can vary by age, research on age-specific, tailored education and promotion strategies should be prioritized. Second, to improve the witnessed arrest rate and bystander CPR rate, which are key factors influencing OHCA prognosis, it is necessary to establish community-based collaborative systems through community health leaders. This also requires a tailored approach that considers age-specific characteristics. Third, when establishing an emergency medical services system, simply expanding the number of medical institutions has its limitations; a strategic design that comprehensively incorporates demographic, geographic, and social factors is necessary.

The limitations of this study are as follows. First, this study alone cannot fully explain the high incidence of OHCA in Chungbuk and Chungnam. Therefore, a more detailed analysis of OHCA-related risk factors is needed at the city, province, and district levels, particularly where the population is aging. Identification of these risk factors is expected to enable the establishment of prevention-oriented response strategies suitable for each community. Second, this study primarily explained the bystander CPR rate in relation to age. However, research considering factors other than age is needed to explain the disparity in bystander CPR rates between Chungbuk and Chungnam, which have similar population distributions. Finally, this study did not include information on regional emergency medical resources that could affect patient prognosis, such as the number of emergency medical institutions per one million people or the status of automated external defibrillator deployment per 10,000 people. Moreover, it did not include details of in-hospital treatment, such as the provision of CPR and defibrillation in the ER or the time to procedures like reperfusion therapy. Therefore, subsequent research considering these factors is necessary.

Ethics Statement: Not applicable.

Funding Source: None.

Acknowledgments: None.

Conflict of Interest: The authors have no conflicts of interest to declare.

Author Contributions: Conceptualization: HJP, JHJ, YHC. Data curation: HJP. Formal analysis: HJP, JHJ, GML, YHC. Project administration: YHC. Visualization: JHJ, GML. Supervision: YHC. Writing – original draft: HJP. Writing – review & editing: HJP, YHC.