PHWR Public Health Weekly Report

Sudden cardiac arrest (SCA) is a legally classified cerebrocardiovascular condition that requires prevention and management [1]. Since 2008, the Out-of-Hospital Cardiac Arrest Surveillance (OHCAS) has been operated annually to support the development of prevention and treatment strategies by investigating the current status of SCA in the Republic of Korea, as well as post-event management and treatment outcomes [2]. Approximately 30,000 SCA cases occur outside hospitals and are transported by emergency medical services (EMS) each year, and despite ongoing monitoring, the nationwide survival rate identified through the surveillance has never exceeded 10%. Although medical treatment is essential for survival and recovery, early emergency response at the moment of occurrence is equally critical. This has led to increasing emphasis on strengthening pre-hospital capacity, particularly at the community level where SCA most commonly occurs. A widely recognized key factor is whether the event was witnessed and whether the witness was able to provide timely and appropriate assistance [3]. As a result, areas with higher population density tend to show higher rates of bystander cardiopulmonary resuscitation (CPR) and correspondingly higher survival rates. However, even when an event is witnessed, outcomes may remain poor if the witness does not know how to respond or if an emergency medical system is not in place to guide them and ensure rapid patient transport. For this reason, the major indicators generated through OHCAS also serve as an important resource for evaluating the effectiveness of local emergency medical systems. Although SCA can arise from various causes, many cases stem from cardiac conditions, and advanced age is a major risk factor. Consequently, SCA occurs more frequently in provinces with larger older adult populations than in more urbanized regions, reflecting distinct regional patterns. From a public health policy perspective, understanding these local trends and identifying areas in need of improvement is essential. Reliable data sources, such as those provided by OHCAS, play a crucial role in this process.

Against this backdrop, the present study was conducted to generate foundational data on SCA incidence and areas for improvement in the Daegu and Gyeongbuk regions, which fall under the jurisdiction of the Gyeongbuk Regional Center for Disease Control and Prevention. Its aim is to help local governments and relevant institutions develop a shared understanding of the issues and establish clear targets for improvement by analyzing factors that may influence survival and recovery, including regional hospital utilization and bystander CPR. Additional contextual considerations relevant to interpreting these findings are also provided.

1. Data Source

Although the OHCAS collects data in the first and second halves of each year, the raw data are released annually. For this study, raw data from the most recent 11-year period (2013–2023) were used (Korea Disease Control and Prevention Agency Approval Number: KDCA-12-02-CA-2025-000139). These data included patients transported by EMS for SCA and for whom medical record reviews had been completed [4]. Since 2013, more than 96% of such patients have had completed reviews in the OHCAS (Supplementary Table 1; available online).

2. Data Analysis

The raw dataset provides three types of regional information: the location where the SCA occurred, the patient’s place of residence, and the location of the treating hospital. In the official OHCAS statistics, all regional analyses are based on the location of occurrence. This study first calculated incidence rates based on residential address to assess potential differences from the occurrence-based incidence rates reported in OHCAS. All other indicators, including survival and recovery, were analyzed according to the occurrence location, consistent with national statistics.

Patient survival and recovery were determined using outcomes from the initial receiving emergency department and from hospital discharge. Records from the receiving hospital were included for patients who were transferred. In this study, an SCA was considered “witnessed” if another person observed it at the moment it occurred; it is acknowledged that not all cases discovered after the event were included [5]. “CPR administration” was defined as CPR performed by laypersons, rather than healthcare providers or individuals performing related duties.

Analyses of occurrence location, witness presence, bystander CPR, and survival outcomes were conducted using data from the most recent three years (2021–2023). This approach ensured adequate sample sizes for subgroup comparisons, as although approximately 30,000 cases occur nationwide each year, sufficient for detailed subgroup analyses, the annual case counts in Daegu and Gyeongbuk are considerably smaller.

All other indicator definitions followed the standard methods used in OHCAS [2].

Over the past 10 years, the incidence of out-of-hospital cardiac arrest (OHCA) has shown a gradual upward trend, reaching its peak in 2022 nationwide (Table 1). The incidence among men was consistently about 1.8 times higher than among women, and Gyeongbuk consistently showed a rate approximately 1.3 times higher than the national average based on residential area. Survival rates increased from 4.8% in 2013 to 8.7% in 2019 but declined by about one percentage point between 2020 and 2022 before partially recovering to 8.6% in 2023 (Figure 1). In Daegu, survival rates peaked at 8.7% in 2019 and remained in the 8% range thereafter. Gyeongbuk showed slightly lower survival rates than Daegu and the national average but improved steadily, reaching 6.1% in 2023. Similarly, neurological recovery rates increased to 5.4% in 2019, declined in 2020 and 2021, and then rose again to a peak of 5.6% in 2023 (Figure 2). Daegu’s recent neurological recovery rate was 5.8%, higher than the national average, while the rate for Gyeongbuk was 3.8%.

Figure 1. Trend of survival rate^a) of out-of-hospital cardiac arrest patient in Daegu and Gyeongbuk
^a)Survival means discharge from emergency center or after admission.

Figure 2. Trend of neurological recovery rate^a) of out-of-hospital cardiac arrest patient in Daegu and Gyeongbuk
^a)Neurological recovery means the score 1 or 2 of Cerebral Performance Category Scale.

Table 1 Occurrence of out-of-hospital cardiac arrest patient among residents of Daegu and Gyeongbuk (2013–2023)

City and province/gender		2013	2014	2015	2016	2017	2018	2019	2020	2021	2022	2023
Nationwide
Total	No. of patient	28,170	29,282	29,959	28,963	28,629	30,179	30,279	31,417	33,041	34,848	33,402
	(incidence rate)	(55.1)	(57.0)	(58.1)	(56.0)	(55.3)	(58.2)	(58.4)	(60.6)	(64.0)	(67.7)	(65.2)
Men	No. of patient	18,244	18,620	19,202	18,530	18,500	19,286	19,505	20,041	20,970	22,233	21,485
	(incidence rate)	(71.3)	(72.5)	(74.5)	(71.7)	(71.6)	(74.6)	(75.4)	(77.6)	(81.4)	(86.7)	(84.3)
Women	No. of patient	9,926	10,662	10,757	10,433	10,129	10,893	10,774	11,376	12,071	12,615	11,917
	(incidence rate)	(38.8)	(41.6)	(41.7)	(40.3)	(39.1)	(42.0)	(41.5)	(43.8)	(46.6)	(48.9)	(46.3)
Daegu
Total	No. of patient	1,198	1,255	1,303	1,316	1,323	1,346	1,331	1,382	1,298	1,309	1,319
	(incidence rate)	(47.9)	(50.3)	(52.4)	(53.0)	(53.4)	(54.7)	(54.6)	(57.1)	(54.4)	(55.4)	(55.8)
Men	No. of patient	795	819	826	844	833	877	839	910	824	868	872
	(incidence rate)	(63.8)	(66.0)	(66.8)	(68.4)	(67.8)	(71.9)	(69.6)	(76.3)	(70.1)	(74.6)	(75.2)
Women	No. of patient	403	436	477	472	490	469	492	472	474	441	447
	(incidence rate)	(32.1)	(34.8)	(38.1)	(37.7)	(39.3)	(37.7)	(39.9)	(38.5)	(39.2)	(36.7)	(37.1)
Gyeongbuk
Total	No. of patient	2,181	2,146	2,140	2,040	2,033	2,108	2,040	2,169	2,107	2,356	2,098
	(incidence rate)	(80.8)	(79.5)	(79.2)	(75.5)	(75.5)	(78.7)	(76.5)	(82.2)	(80.2)	(90.6)	(82.9)
Men	No. of patient	1,399	1,376	1,374	1,309	1,277	1,311	1,327	1,347	1,350	1,469	1,337
	(incidence rate)	(103.2)	(101.5)	(101.2)	(96.5)	(94.4)	(97.3)	(98.9)	(101.3)	(102.0)	(112.0)	(104.4)
Women	No. of patient	782	770	766	731	756	797	713	822	757	887	761
	(incidence rate)	(58.2)	(57.3)	(56.9)	(54.4)	(56.5)	(59.9)	(53.9)	(62.7)	(58.1)	(68.8)	(60.8)

Unit: cases, cases per 100,000 population..

Most patients were transported to hospitals within the city or province where the SCA occurred (annual national range: 96.5–97.9%). In 2023, 99.2% of patients in Daegu were transported to local hospitals, compared with 95.1% in Gyeongbuk (Supplementary Table 2; available online).

Between 2021 and 2023, 64.0% of SCA events occurred in non-public settings (64,815 of 101,291 cases), most often at home (Table 2). The nationwide survival rate for SCA in non-public settings was 6.3%, whereas it was 13.5% for events in public locations. Similar trends were observed in Daegu and Gyeongbuk: survival rates for non-public versus public SCA events were 7.0% and 14.4% in Daegu, and 4.4% and 9.5% in Gyeongbuk, respectively, indicating that survival nearly doubled when SCA occurred in public settings. During the same period, 53.6% of SCAs were witnessed (54,255 of 101,291 cases), with Daegu and Gyeongbuk at 55.2% and 51.1%, respectively (Supplementary Table 3; available online). Nationwide survival for witnessed events was 12.0%, compared with 3.2% for unwitnessed events. Daegu and Gyeongbuk showed similar patterns (12.0% vs. 4.3% and 9.2% vs. 2.1%, respectively). When bystander CPR was performed, survival rates increased to 12.3%, compared with 6.4% when it was not performed, demonstrating nearly a two-fold difference. Similar trends were seen in Daegu and Gyeongbuk (Table 3).

Table 2 Survival rate^a) by the place of occurrence of out-of-hospital cardiac arrest (2021–2023)

Place	Nationwide				Daegu				Gyeongbuk
	Patient	Survived patient	Rate (%)		Patient	Survived patient	Rate (%)		Patient	Survived patient	Rate (%)
All	101,291	7,991	7.9		3,779	321	8.5		6,774	385	5.7
Publicb)	16,845	2,273	13.5		658	95	14.4		1,214	115	9.5
Road/highway	5,665	370	6.5		199	17	8.5		556	17	3.1
Public building	630	138	21.9		32	4	12.5		49	12	24.5
Leisure-related place	719	242	33.7		39	10	25.6		39	15	38.5
Industrial facility	1,831	245	13.4		70	9	12.9		123	18	14.6
Commercial facility	4,876	734	15.1		204	32	15.7		274	32	11.7
Terminal	484	100	20.7		21	3	14.3		19	2	10.5
Others	2,640	444	16.8		93	20	21.5		154	19	12.3
Non-public	64,815	4,054	6.3		2,642	185	7.0		3,898	170	4.4
Home (including garage, garden)	45,817	2,214	4.8		2,007	113	5.6		2,561	84	3.3
Residential facility	361	32	8.9		6	0	0.0		15	2	13.3
Nursing facility	6,733	173	2.6		172	6	3.5		460	5	1.1
Medical facility	2,099	265	12.6		119	17	14.3		99	11	11.1
Farm	1,060	50	4.7		17	1	5.9		181	5	2.8
Inside the ambulance	8,745	1,320	15.1		321	48	15.0		582	63	10.8
Others	3,494	218	6.2		51	0	0.0		302	18	6.0
Unknown	16,137	1,446	9.0		428	41	9.6		1,360	82	6.0

^a)Survival means discharge from emergency center or after admission. ^b)The classification of locations, such as public places, non-public places, and detailed places, follows the classification system of the Out-of-Hospital Cardiac Arrest Surveillance..

Table 3 Survival rate^a) by cardiopulmonary resuscitation by bystander^b) for the patient of out-of-hospital cardiac arrest (2021–2023)

Cardiopulmonary resuscitation	Nationwide				Daegu				Gyeongbuk
	Patient	Survived patient	Rate (%)		Patient	Survived patient	Rate (%)		Patient	Survived patient	Rate (%)
All	101,291	7,991	7.9		3,779	321	8.5		6,774	385	5.7
Non-performed	10,357	664	6.4		832	42	5.0		361	26	7.2
Performed	26,305	3,246	12.3		1,416	153	10.8		1,275	150	11.8
Not applicablec)	12,977	1,777	13.7		558	74	13.3		806	80	9.9
Unknown	51,652	2,304	4.5		973	52	5.3		4,332	129	3.0

^a)Survival means discharge from emergency center or after admission. ^b)Cardiopulmonary resuscitation performed by a bystander excluding paramedics and medical staff before arriving at the hospital. ^c)Witnessed by paramedics and medical staff before arriving at the hospital..

The rate of bystander CPR has also steadily increased nationwide, even during the coronavirus disease 2019 (COVID-19) pandemic. In Daegu, it rose fivefold from 9.6% in 2013 to 50.9% in 2023, and in Gyeongbuk, from 4.2% to 21.9% over the same period (Figure 3).

Figure 3. Trend of CPR by bystander^a) for the out-of-hospital cardiac arrest patient in Daegu and Gyeongbuk
CPR=cardiopulmonary resuscitation. ^a)CPR performed by a bystander excluding paramedics and medical staff before arriving at the hospital.

SCA is a condition in which the heart abruptly stops, and the longer the duration of the arrest, the lower the chances of survival and recovery. Rapid emergency response is therefore essential. Moreover, because SCA incidence increases with age, the continued aging of the population makes strengthening response systems an increasingly critical task. The OHCAS was introduced in 2008 and first applied to out-of-hospital cases that occurred in 2006. Among patients transported by EMS, the incidence was 39.8 per 100,000 population in 2006 and rose to 65.7 per 100,000 population by 2023 [2]. Although the overall trend shows gradual growth, the increase between 2020 and 2022 appears unusually steep. The number of cases decreased slightly in 2023 compared with 2022, and according to the National Fire Agency’s Statistical Yearbook, the number of patients transported for cardiac arrest was 34,338 in 2023 and 33,077 in 2024. Since OHCAS includes only patients transported by EMS, the number of surveyed cases is also expected to decrease in 2024 [6,7]. From 2013 to 2023, incidence rates based on both occurrence and residential locations did not show major differences. For example, Daegu had incidence rates of 53.9 per 100,000 population based on occurrence location and 55.8 per 100,000 population based on residential location in 2023. The corresponding figures for Gyeongbuk were 84.8 and 82.9 per 100,000 population, respectively.

Moreover, national patient survival and neurological recovery rates have generally improved. Although these rates temporarily declined during the COVID-19 pandemic after 2020, the overall trend remained upward. Urban areas tend to show higher rates, while rural areas, including Gyeongbuk, consistently show lower rates. This reflects the greater likelihood in densely populated areas of having large hospitals nearby, more potential witnesses at the time of cardiac arrest, and increased access to professional assistance. With respect to hospital transport, 96.7% of patients nationwide were transported to hospitals within the same city or province in 2023. In Daegu, this proportion reached 99.2%, while in Gyeongbuk, 95.1% of patients were transported within the province. Patients from Gyeongbuk who were transported outside the province were mostly sent to nearby regions such as Daegu (3.4%), Ulsan (1.1%), and other adjacent areas including Chungbuk, Gangwon, Gyeongnam, and Gyeonggi (data not shown). Survival rates varied depending on occurrence location, witness presence, and bystander CPR. Patients who experienced SCA in public settings had approximately twice the survival rate of those in non-public settings. Additionally, survival rates were about four times higher when the event was witnessed, and twice as high when bystander CPR was performed. These trends were consistent nationwide as well as in Daegu and Gyeongbuk. While occurrence location is strongly associated with the likelihood of an SCA being witnessed, most events occur at home, and patients have no control over these circumstances. The stable annual distribution of occurrence location and witness presence further highlights that these factors are largely unmodifiable [2]. By contrast, bystander CPR rates can be improved through public awareness campaigns and expanded CPR training for the general population, thereby enhancing survival outcomes.

Recovery from SCA is unlikely without immediate bystander intervention. CPR must be initiated within 4 to 5 minutes to maintain oxygen delivery to the brain, leaving no time to wait for emergency medical personnel to arrive, even after calling 119 [8]. Thus, policies should continue to promote the mindset that any local resident may become a first responder, and should strengthen public-private collaboration to expand CPR training opportunities, regardless of occupation. Bystander CPR rates have increased across all cities and provinces, with Daegu showing a particularly rapid rise since 2021, ranking first among all regions over the past two years [2]. For comparison, the United States’ OHCA registry, the Cardiac Arrest Registry to Enhance Survival (CARES), reported a nationwide bystander CPR rate of 41.7% in 2024, ranging from 23.8% in Connecticut to 79.7% in Alaska [9]. However, CARES collects data only from a subset of voluntarily participating hospitals, making direct comparison with OHCAS, which captures over 96% of EMS-transported patients, difficult. Despite this limitation, Daegu’s 50.9% bystander CPR rate is highly encouraging. Following a major social incident that heightened national CPR awareness, the local government has focused on establishing an integrated communication system among Daegu City Hall, public health centers, and the Emergency Medical Support Center, as well as conducting hands-on CPR training. These efforts appear to have contributed to improving the effectiveness of CPR education. Moving forward, there is a need to evaluate policy outcomes by comparing CPR training programs across cities and provinces and through expert assessment. Establishing a platform for sharing best practices and benchmarking successful strategies among municipalities is also an important role that relevant agencies can play, using these statistics to further improve overall bystander CPR rates.

The OHCAS is an irreplaceable tool for assessing the incidence and outcomes of OHCA patients, as well as evaluating community response. However, this study has several limitations that should be considered when interpreting the findings. First, the registry is based on EMS and medical records compiled after patient transport, emergency treatment, and follow-up care have been completed. Because data are recorded by various personnel, including paramedics, physicians, nurses, and emergency medical technicians, records are often not standardized and may contain gaps in information. Second, there is a lack of variables that assess bystander interventions, CPR implementation, stepwise treatment and transport, and the appropriateness of subsequent care, which limits the analytical depth. Therefore, the results of this study should be interpreted with caution, as its ecological design restricts the ability to draw causal inferences for individual patients.

In conclusion, this study confirmed that survival after SCA is strongly influenced by whether the event occurred in public, whether it was witnessed, and whether bystander CPR was performed. Although patients cannot control these factors, bystander intervention can positively affect survival and recovery. Thus, it is essential to strengthen relevant policies to expand CPR training within communities and to establish robust systems for evaluating the effectiveness of such education.

Ethics Statement: Not applicable.

Funding Source: None.

Acknowledgments: None.

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

Author Contributions: Data curation: SHK. Formal analysis: SHK. Writing – original draft: YLS, YJJ, SHK. Writing – review & editing: YLS, YJJ, SHK.

Supplementary data are available online.