We aimed to determine the incidence, processes of care, and outcomes in out-of-hospital cardiac arrests (OHCA) in Ansan, South Korea.
From the Ansan Fire Department’s (1-1-9 emergency call number) Emergency Medical Services (EMS) database, we obtained a list of adult cardiac arrest cases occurring between January 2008 and December 2011. We excluded cases with obvious non-cardiac causes, such as trauma, drowning, hanging, and asphyxia. We matched the EMS data with in-hospital care and outcome data. We analyzed basic demographic variables (age and gender), the time and place of incidence, witnesses, bystander cardiopulmonary resuscitation (CPR), major time variables, CPR instructions during transport, initial cardiac rhythm at the scene, and automated defibrillator use.
The overall incidence of OHCA in Ansan was 33.1/100,000 persons per year. Out of 778 adult OHCAs in our study population, bystander CPR was provided in 103 cases (13.2%). Of the 517 OHCAs whose initial rhythms were confirmed, 85 (16.4%) showed shockable rhythms, but only 23 (27.1%) received defibrillation at the scene or during transportation. Of the 106 patients whose spontaneous circulation returned at the hospital, only 6 (5.7%) received mild therapeutic hypothermia. During the study period, 31 patients (4%) survived to discharge from hospitals, and 6 of these discharged patients (19.4%) showed favorable neurologic outcomes.
While the survival rate from OHCA in Ansan is very low, this study provides basic information needed to create improvements. Our analysis suggests that multiple variables contribute to the low OHCA survival rate. Several of these variables are modifiable; addressing them is a clear first step toward strengthening the chain of survival from OCHA in Ansan.
The survival rate from out of hospital cardiac arrest in Korea is still low compared with other developed countries. Moreover, the survival rates in small cities near the capital are much lower than that of Seoul metropolitan area.
To improve survival rate from out-of-hospital cardiac arrests (OHCA), multiple variables should be modified, according to the local features. This study is the first step necessary in improving survival within small cities in Gyeonggi-do province, Korea.
Out-of-hospital cardiac arrest (OHCA) is one of the leading causes of death, and it is regarded as an important public health issue [
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 [
Effective responses to OHCA require emergency medical services (EMS), hospitals, and the public to integrate care and continually monitor interventions [
Ansan City is approximately a one-hour drive from Seoul Metropolitan City and has an area of approximately 150 km2. It consists of residential, commercial, agricultural, and large industrial complexes. As of 2012, the population of Ansan was 759,402 (391,819 men and 367,583 women) [
This was a retrospective cohort review of adult (18 years or older) OHCA in which cardiac arrest was recognized by EMS providers of the Ansan Fire Department (excluding cases in which arrest occurred after EMS arrival). Using the Ansan Fire Department EMS database, we obtained a list of adult cardiac arrest cases between January 2008 and December 2011. We excluded from the sample all cases with obvious non-cardiac causes, such as trauma, drowning, hanging, and asphyxia.
The importance of OHCA to public health prompted Ansan City officials to form the “Committee for Development in Emergency Medical Responses in Ansan City.” The committee members were directors and managers of the city’s Public Health Center, representing the Fire Department’s EMS providers and physicians from the Emergency Medical Centers.
Our team of two trained researchers (one nurse and one emergency physician) used the EMS database of the Ansan Fire Department to gather information about OHCA response in Ansan City. We gathered information on basic demographics (age and gender), the time and place of incidence, witnesses, bystander CPR, CPR instructions during transport, initial cardiac rhythm at the scene, use of an automated defibrillator and major time variables: time between emergency call and EMS arrival, EMS time spent at the scene, and transport time to the hospital.
We also examined hospital data on our sample. There are 12 hospitals in Ansan City to which cardiac arrest patients are transported (A through L). A is a regional emergency medical center with approximately 400 beds, B is a regional emergency medicine clinic with approximately 300 beds, and C is a university hospital that functions as a regional emergency medical center with approximately 600 beds. D through L are hospitals of about 100 beds. We were able to match charts from these hospitals with the corresponding emergency medical transportation (EMT) data by comparing patients’ names (when available on EMT charts), ages, and times of transport to the hospital.
Hospital medical records were obtained in two steps: (1) hospitals received a patient list and a form to fill out and (2) the trained investigators visited the hospitals to verify the data and collect any missing information. Through the medical records investigation, we obtained information on the recovery of spontaneous circulation (ROSC), survival and postcardiac arrest care, including whether therapeutic hypothermia (TH) was delivered and whether coronary angiography was performed. The primary outcome we examined was survival to discharge, measured using the cerebral performance category (CPC) score in patients’ medical records at the time of discharge or transfer. The report forms and data elements in this study were based on the Utstein style reporting template [
Prehospital and hospital data were entered into a Microsoft Excel (Microsoft Co., Redmond, VA, USA) spreadsheet, then transferred to the Stata 12.1 (StataCorp, College Station, TX, USA) program for statistical analysis. Normally distributed continuous data are reported as a mean±standard deviation (SD), and non-normally distributed continuous data are reported as a median with an accompanying interquartile range (IQR). A chi-square test was used to compare categorical variables. A multivariable model analyzed age, sex, witness status, public location, bystander CPR, EMS response interval, and initial EMS rhythm. The decision to include these covariates was based on the scientific understanding that these characteristics can influence resuscitation prognosis. Hosmer and Lemeshow tests were used to evaluate modeling fitness. A multivariate logistic regression analysis was performed to identify factors that significantly influenced survival outcomes. We calculated odds ratios (OR) to determine the strength of these associations, using 95% confidence intervals.
This study was approved by the Institutional Review Board of Korea University Ansan Hospital (IRB number: AS 12014). Under the board’s approval, we were exempted from obtaining written informed consent from enrolled patients.
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%) (
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).
Of the 778 cases, 295 (37.9%) were witnessed. Bystander CPR was provided in 103 cases (13.2%). No cases of automated external defibrillation were reported. Location information indicated that 511/778 of these cardiac arrests (65.7%) occurred in residential areas, and the remaining 267/778 (34.3%) occurred in public places (
The median response time between the report of the incident and the arrival of EMS providers was 6 minutes (IQR, 5 to 9 minutes). EMS providers spent a median of 5 minutes (IQR, 3 to 8 minutes) at the scene to resuscitate and prepare patients for transport. The median transportation distance to the hospital was 2 km (IQR, 1.5 to 3.5 km), and the median transportation time was 5 minutes (IQR, 3 to 6 minutes).
Of the 778 OHCAs, the initial cardiac rhythm at the scene was confirmed in 517/778 (66.5%) cases. Among these, 85/517 (16.4%) showed shockable rhythms, 115/517 (22.3%) showed pulseless electrical activity and 317/517 (61.3%) showed asystole. Of the 83 cases of ventricular fibrillation and the two cases of ventricular tachycardia that required defibrillation, only 23 patients (27.1%) received defibrillation by EMS providers prior to arrival at the hospital.
In 111/778 cases (14.3%), 1-1-9 prearrival telephone CPR instructions were given to bystanders, and 57/111 patients (51.4%) received bystander CPR (
Patients were transported to one of 12 hospitals in the Ansan City area. The number of patients and their survival rates by hospital are shown in
In the multivariate logistic regression analysis, victim’s age, location of arrest, witness of arrest and initial rhythm were significantly correlated with survival to discharge (
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 [
In Korea, various efforts have been made to determine OHCA incidence and 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 [
Rapid defibrillation has been shown to improve the likelihood of good outcomes following OHCA [
In its 2010 guidelines, the American Heart Association added integrated postcardiac arrest care to the chain of survival [
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.
No potential conflict of interest relevant to this article was reported.
The authors appreciate all emergency medical services providers in Ansan Fire Department, who dedicate themselves in spite of a harsh work environment. Also the sincere cooperation of emergency medical facilities and leadership from Public Health Center in Ansan City made this meaningful work possible.
The core data elements of out-of-hospital cardiac arrests (OHCAs) in Ansan City according to the Utstein reporting template.
VF, ventricular fibrillation; VT, ventricular tachycardia; PEA, pulseless electrical activity; EMS, emergency medical service; CPC, cerebral performance category.
Characteristics of included out-of-hospital cardiac arrest cases (n=778)
Characteristic | No. of patients (%) |
---|---|
Gender | |
Male | 458 (58.9) |
Female | 320 (41.1) |
Age (yr), mean±SD | 64.9±18.2 |
Location | |
Private home | 511 (65.7) |
Public | 200 (25.7) |
Unknown | 67 (8.6) |
Witnessed by bystander | 295 (37.9) |
Resuscitation attempted by bystander | 103 (13.2) |
AED application by bystander | 0 |
Initial rhythm at the scene |
|
Shockable | 85 (16.4) |
Not shockable | 432 (83.6) |
This does not include the 261 patients whose initial rhythms were not recorded at the scene.
AED, automated external defibrillator.
Prearrival CPR instructions by emergency medical service providers and provision of bystander CPR
Prearrival CPR instruction | Bystander CPR provision |
P-value | ||
---|---|---|---|---|
Total | Yes | No | ||
Yes | 111 | 57 (51.4) | 54 (48.7) | < 0.001 |
No | 667 | 46 (6.9) | 621 (93.1) | |
Total | 778 | 103 (13.2) | 675 (86.8) |
Values are presented as number (%).
CPR, cardiopulmonary resuscitation.
Number of transferred out-of-hospital cardiac arrest (OHCA) patients and survival rate by hospital
Hospital |
Transferred patients | Discharged alive |
---|---|---|
A | 191 | 8 (4.2) |
B | 171 | 3 (1.8) |
C | 148 | 9 (6.1) |
D | 61 | 2 (3.3) |
E | 59 | 2 (3.4) |
F | 42 | 0 |
G | 34 | 2 (5.9) |
H | 28 | 1 (3.4) |
I | 22 | 2 (9.1) |
J | 11 | 1 (9.1) |
K | 6 | 1 (16.7) |
L | 5 | 0 |
Total | 778 | 31 (4) |
Values are presented as number (%).
Listed as the order of the number of transferred OHCA patients. A is a regional emergency medical center with approximately 400 beds. B is a regional emergency medicine clinic with approximately 300 beds. C is a teaching tertiary university hospital that functions as a regional emergency medical center with approximately 600 beds. The hospitals D through L are hospitals containing about 100 beds.
Postresuscitation care and survival rates in the major transfer hospitals
Hospital | No. of patients | ROSC |
PCI | MTH | Discharged alive |
---|---|---|---|---|---|
A | 148 | 26 (17.6) | 8 (5.4) | 5 (3.4) | 9 (6.1) |
B | 191 | 51 (26.7) | 3 (1.6) | 0 | 8 (4.2) |
C | 171 | 29 (17.0) | 2 (1.2) | 1 (0.6) | 3 (1.8) |
Total | 510 | 106 (20.8) | 13 (2.6) | 6 (1.2) | 20 (3.9) |
Values are presented as number (%).
P=0.042,
P=0.125.
ROSC, return of spontaneous circulation; PCI, percutaneous coronary intervention; MTH, mild therapeutic hypothermia.
The multivariate logistic regression model for survival to discharge
Characteristic | Adjusted OR |
95% CI |
P-value | |
---|---|---|---|---|
Gender | ||||
Male | 1.00 | |||
Female | 1.16 | 0.39 | 3.45 | 0.788 |
Age (yr) | 0.94 | 0.91 | 0.97 | < 0.001 |
Location of arrest | ||||
Private home | 1.00 | |||
Public place | 3.64 | 1.40 | 9.45 | 0.008 |
Arrest witnessed | ||||
No | 1.00 | |||
Yes | 3.58 | 1.35 | 9.50 | 0.010 |
Bystander CPR provided | ||||
No | 1.00 | |||
Yes | 0.93 | 0.30 | 2.91 | 0.902 |
Initial rhythm | ||||
Non-shockable | 1.00 | |||
Shockable | 4.12 | 1.61 | 10.52 | 0.003 |
Call to EMS arrival time | ||||
7 min or less | 2.97 | 0.99 | 8.93 | 0.052 |
Odds ratio (OR) and 95% confidence interval (CI) was calculated with adjustment for related factors (gender, age, location of arrest, witness, bystander cardiopulmonary resuscitation [CPR], initial rhythm, and time between emergency call and emergency medical service [EMS] arrival).