PHWR Public Health Weekly Report

Heart disease and cerebrovascular diseases are the leading causes of death in the Republic of Korea (ROK), accounting for 16.3% of all deaths as of 2023. Heart disease is ranked as the second leading cause of death, while cerebrovascular diseases are ranked as the fourth [1]. The age-standardized mortality rate for heart disease has remarkably decreased over the last four decades in developed countries [2]. Despite this decrease, ischemic heart disease and stroke were still the first and third leading causes of death, as well as the second and fourth causes of disability-adjusted life years (DALYs) in 2021, respectively, remaining the primary cause of disease burden [3]. In ROK, stroke and ischemic heart disease were ranked as the second and ninth leading diseases among all cardio-cerebrovascular disease DALYs, resulting in a high disease burden.

Therefore, the government has enacted the Act on the Prevention and Management of Cardio-cerebrovascular Diseases to alleviate personal suffering and reduce the social burden caused by cardio-cerebrovascular diseases. They have outlined the first (2018–2022) and second (2023–2027) comprehensive plans for managing cardio-cerebrovascular diseases.

In 2021, the Korea Disease Control and Prevention Agency (KDCA) outsourced a project to a private entity to collect essential data for developing and evaluating prevention and management policies related to cardio-cerebrovascular diseases at a national level. The project focused on generating statistics for the incidence of myocardial infarction and stroke, which have the highest mortality and morbidity rates among older adults among cardio-cerebrovascular diseases. The statistics for 2011–2021 were announced in April 2024, followed by updated statistics for 2021 and previous years, as well as statistics for 2022 in December 2024. This report outlines the methods for data collection and statistical analysis used to generate statistics on the incidence of cardio-cerebrovascular diseases and presents major findings for 2022.

1. Data Collection

Statistics on the incidence of cardio-cerebrovascular diseases were generated by collecting data from the national health information database of the National Health Insurance Service (NHIS) and causes of death statistics from Statistics Korea based on conditions. The methodology for calculating disease incidence was applied to process the data. The raw data for statistical analysis were generated by combining data from the personalized national health information database annually offered by the NHIS and causes of death statistics.

The national health information database was used to extract data from all patients with claims assigned I21–I23, I60–I61, and I63–I64 codes, and admitted between January 1, 2002, and December 31, 2022, to identify the incidence of myocardial infarction and stroke with a definite diagnosis and high disease burden among cardio-cerebrovascular diseases. In the classification of diseases, I21, I22, I23, I60, I61, I63, and I64 represent acute myocardial infarction, subsequent myocardial infarction, certain current complications following acute myocardial infarction, subarachnoid hemorrhage, intracerebral hemorrhage, cerebral infarction, and stroke (not specified as hemorrhage or infarction), respectively. The extracted data were reconstructed as a hospitalization episode unit to calculate the number of cases of myocardial infarction and stroke, incidence rates, age-standardized incidence rates by sex and region, and 30-day and 1-year case fatality rates using algorithms.

The health information database uses claims data, which can lead to duplicate claims for the same disease due to splitting medical insurance claims, transferring to another hospital after discharge from the current hospital, and readmission owing to complications. To differentiate duplicate information, details on medical bills were reconstructed to form a single or separate hospitalization episode based on certain conditions: condition 1 was defined as when the time interval between the first and second admissions was >28 days, and condition 2 was defined as when the time interval between the first discharge and the second admission was ≥3 days. Two medical bills with consecutive dates that met both conditions were considered as two separate hospitalization episodes; if they met only one condition, they are treated as a single hospitalization episode (Figure 1).

Figure 1. Definition of myocardial infarction and stroke hospitalization episodes

An algorithm was applied to the reconstructed hospitalization episode to identify the first occurrence and recurrence of myocardial infarction and stroke. An initial occurrence was defined as the onset of a specific event for the first time in a person’s life, whereas recurrence was defined as the subsequent onset of the same event after the initial onset. Of the total hospitalization episodes, the “first event” was determined as the initial occurrence identified by the algorithm in the total hospitalization episodes, and all hospitalization episodes identified by the algorithm as subsequent recurrences were classified as “recurrent event” (Table 1). This study could not investigate the incidence of myocardial infarction and stroke before 2002 because the customized database only contains claims data after 2002. To examine trends over the past decade, data from 2012 to 2022 were analyzed for myocardial infarction and stroke.

Table 1 Identification algorithms for AMI and stroke events

Category	First identification algorithm	Recurrent identification algorithm
AMI
Primary I21a), I22b), I23c) (+)	(ECG OR Cardiac enzyme test OR CAG OR PCI/CABG OR Death	PCI/CABG AND (Episode length ≥3 days OR Death)
Primary I21–I23 (–) Secondary or lower I21–I23 (+)	CAG OR PCI/CABG	-
Stroke
Primary I63d)–I64e) (+)	[(Brain imaging OR Therapeutic intervention) AND (Episode length ≥3 days OR Death)] OR Death	[(Brain imaging OR Therapeutic intervention) AND (Episode length ≥3 days OR Death)] OR Death
Primary I63–I64 (–) All I60f)–I61g) (+)	[(Brain imaging OR Therapeutic intervention) AND (Episode length ≥3 days OR Death)] OR Death	[(Brain imaging OR Therapeutic intervention) AND (Episode length ≥3 days OR Death)] OR Death
Primary I63–I64 (–) All I60–I61 (–) Secondary or lower I63–I64 (+)	Therapeutic intervention AND (Episode length ≥3 days OR Death)	-
Primary I63–I64 (–) Primary I60–I61 (–) Secondary or lower I60–I61, I63–I64 (+)	-	Therapeutic intervention AND (Episode length ≥3 days OR Death)

AMI=acute myocardial infarction; CABG=coronary artery bypass grafting; CAG=coronary angiography; ECG=electrocardiogram; PCI=percutaneous coronary intervention; -=not available. ^a)I21: AMI. ^b)I22: subsequent myocardial infarction. ^c)I23: certain current complications following AMI. ^d)I63: cerebral infarction. ^e)I64: stroke, not specified as hemorrhage or infarction. ^f)I60: subarachnoid hemorrhage. ^g)I61: intracerebral hemorrhage..

2. Statistical Calculations

The number of cases by total and sex, incidence rates by total, sex, and classification of incidence, age-standardized incidence rates, incidence rates by types of medical institutions, and age-standardized incidence rates by region were used as the calculation index for incidence. Case fatalities of 30-day and 1-year cases, by total, sex, and age group, were calculated for case fatality.

The number of cases was the sum of the first occurrence and the number of subsequent recurrences. An initial occurrence was defined as the onset of a specific event for the first time in a person’s life, whereas a recurrence was defined as the subsequent onset of the same event after the initial onset. The incidence rate is calculated by dividing the number of cases by the registered central resident population for the specific year and then multiplying by 100,000. In other words, it is a ratio of the number of disease cases per 100,000 population. The case fatality rate was calculated by dividing the number of deaths within 30 days and 1 year after the disease onset for the specific year by the total number of disease cases and then multiplying by 100. The 2005-registered central resident population was used as the standard population to calculate age-standardized incidence rates. Sex-standardized rates were calculated separately based on the standard population of each sex.

1. Incidence of Myocardial Infarction

The incidence of myocardial infarction in 2012 and 2022 is shown in Table 2. In 2022, 34,969 cases of myocardial infarction occurred, with 25,944 (74.2%) cases in males and 9,025 (25.8%) cases in females (Table 2). Regarding the types of hospital where patients were diagnosed initially, 14,902 cases were diagnosed in upper-level general hospitals, followed by 19,584 in general hospitals, 347 in hospitals, and 136 in other medical facilities. In terms of age groups, 4 cases were in the 0–19 years age group, 77 in 20–29 years age group, 587 in 30–39 years age group, 2,839 in 40–49 years age group, 6,769 in 50–59 years age group, 9,578 in 60–69 years age group, 8,006 in the 70–79 years age group, and 7,109 in the ≥80 years age group. Of the total cases, 31,604 cases were first events and 3,365 were recurrent events. The recurrence rate of myocardial infarction increased from 6.5% in 2012 to 9.6% in 2022.

Table 2 Trends in the number of MI cases and incidence rate (2012–2022)

Category	MI number of cases (cases, %)			MI incidence rate (cases per 100,000 population)
	2012	2022		2012	2022
Total	23,509 (100.0)	34,969 (100.0)		46.7	68.2
Total (age-standardized)a)	-	-		36.2	38.6
Sex
Male	16,186 (68.9)	25,944 (74.2)		64.3	101.6
Female	7,323 (31.1)	9,025 (25.8)		29.1	35.1
Age group (yr)
0–19	9 (0.0)	4 (0.0)		0.1	0.0
20–29	43 (0.2)	77 (0.2)		0.6	1.2
30–39	494 (2.1)	587 (1.7)		6.1	8.8
40–49	2,482 (10.6)	2,839 (8.1)		28.5	35.2
50–59	5,110 (21.7)	6,769 (19.4)		67.8	79.2
60–69	5,289 (22.5)	9,578 (27.4)		125.4	132.5
70–79	6,372 (27.1)	8,006 (22.9)		223.9	213.3
80+	3,710 (15.8)	7,109 (20.3)		357.7	327.5
Type of event
First	21,973 (93.5)	31,604 (90.4)		43.6	61.7
Recurrent	1,536 (6.5)	3,365 (9.6)		3.1	6.6
First hospitalization
Tertiary hospital	11,443 (48.7)	14,902 (42.6)		22.7	29.1
General hospital	11,026 (46.9)	19,584 (56.0)		21.9	38.2
Community hospital	798 (3.4)	347 (1.0)		1.6	0.7
Others	242 (1.0)	136 (0.4)		0.5	0.3
Local (age-standardized)a)
Seoul	3,944 (16.8)	5,573 (15.9)		32.3	34.9
Busan	1,856 (7.9)	2,697 (7.7)		37.8	41.7
Daegu	1,419 (6.0)	1,654 (4.7)		45.4	38.9
Incheon	1,068 (4.5)	1,866 (5.3)		33.8	38.9
Gwangju	653 (2.8)	1,053 (3.0)		40.2	45.2
Daejeon	683 (2.9)	866 (2.5)		40.1	36.8
Ulsan	406 (1.7)	590 (1.7)		34.6	33.3
Sejong	-	155 (0.4)		-	33.0
Gyeonggi	4,415 (18.8)	7,975 (22.8)		33.4	37.9
Gangwon	815 (3.5)	1,175 (3.4)		34.3	37.4
Chungbuk	791 (3.4)	1,176 (3.4)		36.2	37.8
Chungnam	1,069 (4.5)	1,466 (4.2)		34.9	35.5
Jeonbuk	1,022 (4.3)	1,332 (3.8)		35.5	36.4
Jeonnam	1,290 (5.5)	2,174 (6.2)		38.9	53.4
Gyeongbuk	1,816 (7.7)	2,303 (6.6)		41.6	41.5
Gyeongnam	1,895 (8.1)	2,458 (7.0)		42.2	40.8
Jeju	338 (1.4)	452 (1.3)		45.0	42.0
Otherb)	29 (0.1)	4 (0.0)		-	-

MI=myocardial infarction; -=not available. ^a)Age-standardized: age-standardized based on the 2005 mid-year registration population. ^b)Other: cases with unknown regional information in the national health insurance eligibility data are classified..

In 2022, the incidence rate of myocardial infarction per 100,000 population was 68.2 cases, with 101.6 cases in males and 35.1 cases in females. Regarding age groups, 0.0 cases were in the 0–19 years age group, 1.2 in 20–29 years age group, 8.8 in 30–39 years age group, 35.2 in 40–49 years age group, 79.2 in 50–59 years age group, 132.5 in 60–69 years age group, 213.3 in 70–79 years age group, and 327.5 in the ≥80 years age group. The incidence was higher in males than in females and increased with age. The male-to-female ratios increased from 2.2 in 2012 to 2.9 in 2022.

Although the age-standardized incidence rate per 100,000 population increased by 6.6%, from 36.2 cases in 2012 to 38.6 cases in 2022, the rate has been decreasing since 2020. The highest rates were reported in Jeollanam-do (53.4 cases) and Gwangju (45.2 cases), whereas the lowest rates were reported in Sejong (33.0 cases) and Ulsan (33.3 cases).

In 2022, the 30-day case fatality rate of myocardial infarction was 9.0%, with a higher rate for females (13.2%) than for males (7.5%). The case fatality rate increased with age and was the highest among older adults aged ≥80 years, accounting for 20.5%. The 1-year case fatality rate was 15.8%, with 13.3% for males and 23.1% for females. Both 30-day and 1-year case fatality rates have remained stable for the past decade without any significant changes (Figure 2).

Figure 2. Trend in 30-day and 1-year fatality rates of acute myocardial infarction (2012–2022)

2. Incidence of Stroke

The incidence of stroke in 2012 and 2022 is shown in Table 3. In 2022, there were 110,574 cases of stroke, with 61,988 (56.1%) cases in males and 48,586 (43.9%) in females. Patients were initially diagnosed in different types of hospitals: 36,630 in upper-level general hospitals, followed by 64,887 in general hospitals, 6,549 in hospitals, and 2,508 in other medical facilities. A higher number of cases of stroke were observed at general hospitals than that of cases of myocardial infarction. In terms of age groups, 363 cases were in the 0–19 years age group, 580 in 20–29 years age group, 1,911 in 30–39 years age group, 5,950 in 40–49 years age group, 15,264 in 50–59 years age group, 25,719 in 60–69 years age group, 27,888 in 70–79 years age group, and 32,899 in the ≥80 years age group. Of the total cases, 88,011 were first events and 22,563 were recurrent events. The recurrence rate of stroke increased from 17.5% in 2012 to 20.4% in 2022.

Table 3 Trends in the number of stroke cases and incidence rate (2012–2022)

Category	Stroke number of cases (cases, %)			Stroke incidence rate (cases per 100,000 population)
	2012	2022		2012	2022
Total	100,673 (100.0)	110,574 (100.0)		200.0	215.7
Total (age-standardized)a)	-	-		152.7	114.6
Sex
Male	53,352 (53.0)	61,988 (56.1)		211.8	242.7
Female	47,321 (47.0)	48,586 (43.9)		188.1	188.9
Age group (yr)
0–19	537 (0.5)	363 (0.3)		4.8	4.4
20–29	549 (0.5)	580 (0.5)		8.3	8.9
30–39	2,146 (2.1)	1,911 (1.7)		26.4	28.8
40–49	7,717 (7.7)	5,950 (5.4)		88.6	73.8
50–59	16,956 (16.8)	15,264 (13.8)		225.0	178.6
60–69	20,546 (20.4)	25,719 (23.3)		487.1	355.7
70–79	32,131 (31.9)	27,888 (25.2)		1,129.2	743.2
80+	20,091 (20.0)	32,899 (29.8)		1,937.1	1,515.7
Type of event
First	83,039 (82.5)	88,011 (79.6)		164.9	171.7
Recurrent	17,634 (17.5)	22,563 (20.4)		35.0	44.0
First hospitalization
Tertiary hospital	33,229 (33.0)	36,630 (33.1)		66.0	71.5
General hospital	49,947 (49.6)	64,887 (58.7)		99.2	126.6
Community hospital	13,091 (13.0)	6,549 (5.9)		26.0	12.8
Others	4,406 (4.4)	2,508 (2.3)		8.8	4.9
Local (age-standardized)a)
Seoul	15,549 (15.4)	17,157 (15.5)		127.7	101.6
Busan	7,599 (7.5)	7,800 (7.1)		156.5	115.2
Daegu	5,330 (5.3)	5,409 (4.9)		171.0	119.8
Incheon	4,633 (4.6)	5,570 (5.0)		147.6	112.4
Gwangju	2,388 (2.4)	2,520 (2.3)		145.5	105.6
Daejeon	2,527 (2.5)	2,730 (2.5)		149.8	109.9
Ulsan	1,696 (1.7)	1,905 (1.7)		151.6	108.0
Sejong	-	501 (0.5)		-	104.8
Gyeonggi	18,477 (18.4)	23,983 (21.7)		140.0	109.5
Gangwon	4,149 (4.1)	4,148 (3.8)		169.1	120.0
Chungbuk	3,944 (3.9)	4,355 (3.9)		171.1	131.2
Chungnam	5,081 (5.0)	5,221 (4.7)		156.8	115.4
Jeonbuk	5,662 (5.6)	5,604 (5.1)		179.8	134.5
Jeonnam	6,039 (6.0)	5,798 (5.2)		168.5	125.5
Gyeongbuk	8,250 (8.2)	7,853 (7.1)		180.6	127.4
Gyeongnam	7,879 (7.8)	8,532 (7.7)		170.8	129.8
Jeju	1,260 (1.3)	1,474 (1.3)		155.0	119.5
Otherb)	210 (0.2)	14 (0.0)		-	-

-=not available. ^a)Age-standardized: age-standardized based on the 2005 mid-year registration population. ^b)Other: cases with unknown regional information in the national health insurance eligibility data are classified..

In 2022, the incidence rate of stroke per 100,000 population was 215.7 cases, with 242.7 cases in males and 188.9 cases in females. In terms of age groups, 4.4 cases were in the 0–19 years age group, 8.9 in 20–29 years age group, 28.8 in 30–39 years age group, 73.8 in 40–49 years age group, 178.6 in 50–59 years age group, 355.7 in 60–69 years age group, 743.2 in 70–79 years age group, and 1,515.7 in the ≥80 years age group. The rate was the highest among older adults aged ≥80 years.

The age-standardized incidence rate per 100,000 population decreased by 25.0%, from 152.7 cases in 2012 to 114.6 cases in 2022, and has continued to decline in both males and females for the past decade. The trend in the age-standardized incidence rate of stroke by region was analyzed and showed a reduction for all regions over the past decade; the greatest reduction in the rate was seen in Gyeongsangbuk-do (180.6→127.4 cases) and Daegu (171.0→119.8 cases).

In 2022, the 30-day case fatality rate of stroke was 7.9%, including 8.2% for first events and 6.5% for recurrent events. The total case fatality rate and case fatality rate for the first stroke decreased gradually from 2012 to 2019, followed by an increase since 2020. The case fatality rate was higher for first events than for recurrent events, with the highest rates among older adults aged ≥80 years. The 1-year case fatality rates were 20.1% for total, 19.8% for first events, and 21.2% for recurrent events in 2022, which have gradually decreased, followed by an increase since 2020 (Figure 3).

Figure 3. Trend in 30-day and 1-year fatality rates of stroke (2012–2022)
recur=recurrent.

The KDCA conducted a project to generate statistics for cardio-cerebrovascular diseases based on the Act on the Prevention and Management of Cardio-cerebrovascular Diseases and to establish preliminary data and a basis for cardio-cerebrovascular disease management policy. The statistics on the incidence of cardio-cerebrovascular diseases were approved as national statistics in 2023, with the 2021 statistics being announced for the first time in April 2024. In addition, the 2022 statistics were announced in December 2024 by adjusting the announcement date to December of the second following year, which improved the utilization and timeliness of statistics. Compared with the rates in 2012, the age-standardized incidence rate of myocardial infarction increased by 6.6% in 2022, whereas the rate of stroke decreased by 25%. In the last decade, the incidence of myocardial infarction increased, whereas that of stroke decreased. The annual mortality rate was 15.8% for patients with myocardial infarction and 19.8% for stroke patients. There is a proposal to generate annual statistics for the incidence of cardio-cerebrovascular diseases and use it as a basis for developing disease management policies.

In 2025, to include statistics on additional diseases, a disease with high mortality rates following myocardial infarction and stroke that increases substantially will be selected, and methods for calculating incidence or prevalence rates will be reviewed. A plan has been developed to gradually include statistics on additional diseases in the comprehensive analysis of death rate, medical cost burden from an aging population, availability of calculated data, and required political intervention. The KDCA will continue to establish plans to improve demand and utilization among statistics users and will strive to develop and announce new statistical tables for analyzing the incidence of cardio-cerebrovascular diseases in ROK.

Ethics Statement: Not applicable.

Funding Source: None.

Acknowledgments: None.

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

Author Contributions: Conceptualization: YHY, HWJ, CSP. Data curation: YHY. Supervision: CSP. Writing – original draft: YHY, HWJ. Writing – review & editing: YHY, HWJ, CSP.