Cardiovascular diseases (CVDs) accounted for 31% of total deaths in the world and more than 50% of the CVD deaths occurred in Asian countries. In China, CVDs accounted for about 40% of the total deaths. Heart diseases are part of the CVDs spectrum, and previous evidence showed high burden of certain subcategories of heart disease[4–7]. In 2020, the age-standardized mortality rate (ASMR) in China was as high as 103.16/100,000 of ischemic heart disease (IHD) and 21.86/100,000 of hypertensive heart disease (HHD). Similar results have been reported for years of life lost due to the major CVDs. However, none of these studies reported data separately for urban versus rural areas. The secular trend of different subcategories of heart diseases in different areas also remained unclear. We, therefore, conducted a longitudinal analysis using data from the China National Mortality Surveillance System (NMSS) from 2013 to 2020.
The China NMSS is an ongoing registry that covers over 300 million individuals (24% of China’s total population) from 605 surveillance points in 31 provincial-level administrative divisions (excluding Hong Kong, Macao, and Taiwan), and collects individual death information in real-time using a web-based technologies. Detailed descriptions of NMSS have been reported elsewhere. The basic surveillance unit is district (for urban areas) or county (for rural areas). All deaths within a unit, both inside and outside hospitals, were entered into an online reporting system by local centers for disease control and prevention at district or county levels. The cause of death is determined by a trained staff of the local hospital and coded according to the International Classification of Diseases–10th Revision (ICD-10th). For deaths that occurred outside a hospital without recent medical records, the cause of death was determined by the same personnel using a standard procedure, as described previously[9,10]. Data from the China NMSS have been shown to be nationally and provincially representative[3,11]. Classification of death into urban versus rural area was based on the permanent residence address. Urban areas included districts in municipalities or prefecture-level cities, and rural areas included counties and county-level cities. This classification was identical to that used in the most recent China Cause-of-death Surveillance Data Set 2020. There were certain under-reporting in China NMSS, particularly in rural areas; accordingly, under-reporting survey was conducted every 3 years since 2006. The data used in the current study included under-reporting for the 2012–2017 period and were adjusted for the 2018–2020 period based on the under-reporting rate in 2017. Population data were obtained from National Bureau of Statistics, and the reference population for direct standardization was acquired from 2010 population census. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013) and approved by ethics committee of National Center for Chronic and Noncommunicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention (#202219, date: July 26, 2022). Due to the retrospective nature of the study, the requirement for informed consent was waived.
All deaths with underlying cause of death as heart diseases were included in the analysis. The types of analyzed heart diseases included total heart diseases (I00-I59, I70-I99, and Q20-Q28), IHD (I20-I25), HHD (I11), rheumatic heart disease (RHD) (I01-I09), cardiac arrest (I46), nonrheumatic valvular heart diseases (NRVHDs) (I34-I38), aortic aneurysm (AA) (I71), pulmonary embolism (I26), acute pericarditis (I30), acute myocarditis (I40), cardiomyopathy (I42), and congenital heart disease (CHD) (Q20-Q28).
Causes of heart disease deaths were ranked based on proportion of each subcategory of heart diseases during the entire study period. Crude mortality rates (CMR) of heart diseases were compared between urban and rural areas in 2020. A trend analysis was performed for ASMR of major heart diseases by gender and region to analyze the change over time. Proportion of different heart diseases was compared among three age groups (<45 years, 45–64 years, and above 65 years). Geographic variation of ASMR of total heart diseases in 2020 and the percent change during 2013–2020 was also examined.
All analyses were conducted using SAS version 9.4 (SAS Institute; Cary, NC, USA) and R version 4.0.4 (The R Foundation for Statistical Computing, Vienna, Austria).
IHD, HHD, and RHD were the top three causes of heart disease deaths from 2013 to 2020 (Figure 1). AA moved from the eighth place in 2013 to the fifth place in 2020. NRVHDs moved from the 10th place in 2019 to the ninth place in 2020. The ranking of pulmonary embolism, cardiomyopathy, and acute myocarditis moved down during the study period.
IHD remained the leading cause of heart disease deaths in 2020, with substantially higher CMR (134.87/100,000) than HHD (19.94/100,000), RHD (3.94/100,000), and cardiac arrest (3.62/100,000). Urban areas had lower CMR of IHD (120.31/100,000 vs. 145.32/100,000 in rural areas), HHD, RHD, pulmonary embolism, CHD, and acute myocarditis, but higher CMR of cardiac arrest (4.76/100,000 vs. 2.80/100,000), AA, cardiomyopathy, and NRVHDs (Table 1).
Table 1 -
The Crude mortality rate (/100,000) of subcategories of heart diseases in China, 2020
|Ischemic heart disease
|Hypertensive heart disease
|Rheumatic heart disease
|Congenital heart disease
|Nonrheumatic valvular heart diseases
The secular trend of ASMR varied across subcategories of heart disease during the study period. The ASMR of IHD remained at a high level, from 104.65/100,000 in 2013 to 97.98/100,000 in 2020, with consistently higher level in men versus women and in rural versus urban areas throughout the study period. The ASMR of HHD decreased from 17.52/100,000 in 2013 to 14.22/100,000 in 2020, with consistently higher level in men versus women and in rural versus urban areas throughout the study period. The ASMR of RHD decreased from 4.25/100,000 in 2013 to 2.89/100,000 in 2020 (32.09% reduction), with higher level in women than men and in rural versus urban areas. The ASMR of cardiac arrest decreased from 3.82/100,000 in 2013 to 2.24/100,000 in 2016 but increased to 2.90/100,000 in 2020, with higher level in men and in urban areas. The ASMR of AA increased from 0.55/100,000 in 2013 to 0.88/100,000 in 2020 (58.60% increase), with higher level in men and in urban areas. The ASMR of NRVHDs increased from 0.19/100,000 in 2013 to 0.25/100,000 in 2020 (31.51% increase), with higher level in men and in urban areas (Figures 2 and 3).
The spectrum of heart diseases differed significantly across age groups. In 2020, the proportions of IHD and HHD increased with age; the highest proportion of IHD and HHD occurred in the ≥65-year age group (81.67% and 13.08%, respectively). CHD accounted for 15.64% of the total heart disease deaths in the youngest age group. The proportion of cardiac arrest was 11.51% in the <45-year age group, 5.02% in the 45–64-year age group, and1.42% in the ≥65-year age group (Figure 4).
The ASMR of heart diseases varied significantly across geographic locations. The standard deviation of ASMR among the 31 provinces was 50.04 in 2013 and decreased to 39.76 in 2020. The ASMR of heart diseases was significantly higher in northern provinces than in southern provinces. In 2020, the highest ASMR was seen in Xinjiang (198.14/100,000), Inner Mongolia (196.16/100,000), Henan (195.99/100,000), Qinghai (189.79/100,000), and Hebei (182.36/100,000); the lowest ASMR was in Shanghai (62.19/100,000), Zhejiang (65.63/100,000), Jiangsu (72.07/100,000), Sichuan (85.63/100,000), and Hainan (89.72/100,000) (Figure 5A). The ASMR of heart diseases decreased in all provinces with an exception in Xinjiang (2.87% increase), particularly in Tibet (−43.08%), Tianjin (−38.10%), Jiangsu (−32.08%), Shanxi (−30.85%), and Heilongjiang (−30.44%) (Figure 5B).
The results of the current study clearly showed IHD remained the leading cause of heart disease death, with higher mortality rate than other heart diseases. Increasing trend was observed for ASMR of cardiac arrest, AA, and NRVHDs during the study period. Substantial geographical variations were observed across different provinces in China.
IHD was the second leading cause of deaths in China in 2017 and is expected to surpass stroke as the leading cause of death in the near future. Previous studies showed high mortality rate in out-of-hospital patients with IHD. The lack of cardiopulmonary resuscitation remains a universal problem, with almost no improvement, especially in rural areas[15,16]. HHD is highly heterogeneous, with clinical manifestations ranging from asymptomatic, mild chest tightness, palpitations to dyspnea and even biventricular failure and sudden death. Currently, the control rate of hypertension in the entire world is 32.5%. The crude prevalence rate of hypertension among Chinese residents aged ≥18 years was 27.9% and as high as 59.8% in those aged ≥75 years in 2012–2015. Controlling of hypertension is critical in preventing HHD mortality, and the findings from the current study suggested that more efforts should be made in promoting public awareness of hypertension and optimizing the infrastructure and programs to increase the control rate of hypertension. RHD is one of the sequelae of acute rheumatic fever, usually caused by streptococcal pharyngitis. Despite a decline during the study period, the mortality rate was still higher than that in the global statistics. Patients with cardiac arrest have a very high case fatality rate, and the current global out-of-hospital survival rate was 2%–11%. According to the American Heart Association, the in-hospital and out-of-hospital survival rates in adult patients with cardiac arrest were 23.8% and 10.6%, respectively. In contrast, the out-of-hospital survival rate of such patients was <1% in China, indicating a dire need for improvements in this area.
The ASMR of IHD, HHD, and RHD displayed a downward trend during the study period but remained higher than other heart diseases. The ASMR of cardiac arrest increased after 2016. Implementation of automated external defibrillator outside hospital settings in China is minimal and must be strengthened. Consistent with a previous study, we found increasing ASMR of AA from 2013 to 2020, which in turn may be attributed to increased metabolic risk factors, such as high blood pressure and atherosclerosis[24,25], and improved diagnostic standards and screening technology. In sharp contrast to the Global downward trend[27,28], we found a slight increase in the ASMR of NRVHDs in recent years, suggesting insufficient programs for diseases with low but increasing ASMR.
The ASMR of IHD, HHD, cardiac arrest, NRVHDs, and AA was higher in men than in women, likely due to higher exposure to heart diseases related risk factors. In 2020, the CMR of IHD, HHD, RHD, pulmonary embolism, CHD and acute myocarditis was higher in rural versus urban areas. Such a discrepancy may be attributed to lower rate of awareness and treatment of hypertension in rural populations. In contrast, the CMR of cardiac arrest, AA, cardiomyopathy, and NRVHDs was higher in urban areas, possibly due to higher stress level in urban residents, as well as higher rate of detection due to more abundant medical resources.
The spectrum of heart diseases differed significant across different age groups. The proportion of CHD in lower age was significantly higher than in other age groups. IHD and HHD accounted for >85% of the heart disease patients aged ≥45 years. It is noteworthy that death from cardiac arrest accounted for 11.51% of heart disease death in the younger age group. Future studies are needed to identify the causes for cardiac arrest in this population. In general, heart disease mortality was significantly in northern versus southern provinces. The mortality in Xinjiang is three times higher than that in Shanghai. The underlying mechanism for such differences are complex and may include higher prevalence of hypertension, unhealthy lifestyles (eg, salty food intake), and relatively poor healthcare resources in northern part of the country.
The ASMR of heart diseases in most provinces of China decreased during the study period, possibly due to upgrading of medical technologies, improvement in public health environment, and increased control of risk factors. A particularly critical improvement is the establishment of a basic network of chest pain centers in most provinces across China, which has been shown to dramatically improve the treatment of heart diseases[31,32]. The increase in the ASMR of heart diseases during the study period in Xinjiang is perplexing and may involve increased exposure to risk factors and lifestyle issues. Higher ASMR is associated with lower sociodemographic index. We also noticed decreased standard deviation of ASMR of heart diseases in and number of provinces during the study period, indicating narrowing regional disparity. Nevertheless, studies needed at the province-level to identify the causes for the changes, particularly in regions with increasing ASMR.
Population aging is a critical factor that drives heart disease death. Based on the most recent estimate, there will be 365 million people (26.1% of total population) aged ≥65 years in China in 2050. Accordingly, we expect a rise of heart disease deaths in the future. Established risk factors of heart diseases include increased systolic blood pressure, increased low-density lipoprotein cholesterol, smoking, increased body mass index, and increased blood glucose. The impact of unhealthy diet is a particular problem in China. Average salt intake by Chinese residents (14.5 g/day) is almost three times the recommended level by WHO (5.0 g/day). The Chinese government issued a plan to reduce CVD mortality by 15% by 2025 (vs. 2015). Healthy China Action Plan (2019–2030) issued by China State Council put forward a plan with a set of comprehensive and more defined measures, including reduction of modifiable risk factors, blood pressure and blood lipid monitoring, and self-management.
Despite a decrease in heart diseases mortality during the study period, the estimated number of heart disease deaths was up to 2.53 million in 2020. The estimated number of death due to IHD, HHD, RHD, cardiac arrest, AA, and NRVHDs was 1904.13 thousand, 281.93 thousand, 55.58 thousand, 51.10 thousand, 15.82 thousand, and 4.82 thousand, respectively. Expected increase in the number of heart disease deaths as the result of rapid aging of the Chinese population represents a major challenge.
This study has several limitations. First, data quality is affected by under-reporting, particularly in the western part of the country. The mortality rates, therefore, may be underestimated despite measures that corrected the under-reporting. Second, the accuracy of reported causes of death that occurred outside hospital is questionable, particularly in rural areas. Third, data regarding risk factors of heart diseases were not collected. Future studies that examine the interaction of risk factors with the incidence and mortality rate of heart diseases are needed.
The overall mortality rate of heart diseases decreased during the 2013–2020 period in China. IHD remained the leading cause of heart disease death in China. There was a trend for increasing mortality of cardiac arrest, AA, and NRVHDs. Regional disparity also existed (higher ASMR in northern vs. southern provinces).
Conceptualization, funding acquisition and project administration: PY, LW and MZ; data curation and methodology: ZL, YX and WL; formal analysis: ZL and YX writing the original draft: ZL; and writing—review & editing: PY and YH
CONFLICTS OF INTEREST STATEMENT
Yong Huo is the Editorial Board member of Cardiology Plus. The article was subject to the journal’s standard procedures, with peer review handled independently of this Editorial Board member and their research groups. The remaining authors declare that they have no financial conflict of interest with regard to the content of this report.
The authors thank all provincial and local health administrative departments, the Centers for Disease Control and Prevention.
DATA SHARING STATEMENT
Research materials will be made available to other researchers upon request to the corresponding author.
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