Most previous reports regarding the epidemiology of cardiovascular disease (CVD) in China focus on ischemic heart disease (IHD) and stroke, the two major types of CVD.[1,2] Data regarding the burdens and epidemiological trends of other types of heart diseases are relatively inadequate. A paper entitled, “Mortality trend of heart diseases in China, 2013–2020,” published in this issue of Cardiology Plus by Zheng et al, presents the epidemiological characteristics and temporal trends of mortality for IHD and other types of heart disease in the Chinese population.
Some findings from this study need to discuss specifically.
SIGNIFICANT GEOGRAPHIC DIFFERENCES IN AGE-STANDARDIZED IHD MORTALITY
While the results of the current study indicated that the age-standardized mortality of IHD decreased in most of provinces from 2013 to 2020, remarkable geographic differences in the mortality of IHD remained in 2020, with similar patterns reported in the early 1990s and 2015[4,5]. In 2020, the age-standardized mortality of IHD in high-risk regions of China was as much as three times higher than that in low-risk regions. Theoretically, significant geographic differences of age-standardized IHD mortality can be explained by the regional lifestyle and living environment differences; different levels of risk factors, treatment, and control of the risk factors; and the capacity of acute care of IHD and secondary prevention.
First, the lifestyles and living environments of a region are the most upstream determinants of IHD burden and include the proportion of the population with unhealthy diets, physical inactivity, smoking, or obesity, as well as the extent of air pollution. Second, the levels of risk factors and awareness, treatment, and control of these risk factors in a region are major determinants of the risk of age-standardized IHD incidence in the region, especially prevalence of hypertension, dyslipidemia, and diabetes in this region. Third, the capacity of acute care to treat acute events of IHD and the quality of care for patients with chronic IHD are also critical determinants of age-standardized IHD mortality in a region. The preventive strategies targeted on the three aspects are called primordial, primary, and secondary prevention. Persistent geographical differences in age-standardized IHD mortality in China have been observed for more than 30 years, indicating that disparities in implementations of primordial, primary, and secondary prevention strategies persist among different regions in China. An understanding of the particular problems and weaknesses in primordial, primary, and secondary prevention in a specific region, especially regions with high age-standardized IHD mortality, will be helpful in determining effective and specific solutions to develop localized strategies.
The China Cardiovascular Health Index (CHI), a well-designed index system, was developed and issued by the Chinese Center of Disease Prevention and Control, and the Chinese Heart Association provided a useful performance measures system for the effectiveness of prevention strategies in a region. The CHI consists of five dimensions: prevalence of CVD, exposure to risk factors, prevention and control of risk factors, treatment, and public health policy and service ability. Fifty-two indicators are included under the five dimensions. A previous study examined the performance of each Chinese province in CVD prevention by assessing these indicators of CHI. The total CHI scores were associated with age-standardized IHD mortality.
Another critical determinant of IHD mortality is the aging of the population. Unfortunately, the study does not provide adequate information regarding crude IHD mortality in each region and temporal trends, which reflect the real burden of IHD in a region with a more meaningful value for the planning and allocation of medical resources.
CARDIAC SUDDEN DEATH AND CONGENITAL HEART DISEASES IN POPULATION AGED <45 YEARS
The current study reported that the proportions of cardiac sudden death and congenital heart disease in total deaths of heart disease aged < 45 years were notably higher than that in older age groups. The cause of sudden death in young people is often unclear. An autopsy study conducted in China reported in deceases of age <35, 35% was myocarditis, 22% were due to unknown causes, and 10.4% were due to IHD. Few previous studies have focused on prevention and treatments of heart diseases other than IHD in young people. The results of this study may lead to more research regarding heart diseases in young and promote the development of effective strategies to prevent premature deaths from heart diseases in the young population.
EMERGING IMPORTANCE OF THE BURDENS OF AORTIC ANEURYSMS AND NON-RHEUMATIC VALVULAR HEART DISEASES
It worth to notice that aortic aneurysms and non-rheumatic valvular heart diseases upgraded their ranks as causes of deaths of heart diseases from 2013 to 2015, with significant raising trends in age-standardized mortalities. The raising trend of mortalities from the two diseases may continue because the risks of both diseases are closely associated with population aging. Age-standardized mortality may underestimate the burden of aortic aneurysms and non-rheumatic valvular heart diseases, especially when the population structure from 2010 census, which was more than 20 years ago, are used as a standard age structure. The population aging will rapidly progress in China over the next 30 years. Degenerative changes of the cardiovascular system will play a more essential role in CVDs. As life expectancy increases, the numbers of aging patients with more than one complicated heart diseases may also increase. Although the improved diagnostic methods for aortic aneurysms may affect the increasing mortality rate, the challenge of epidemiological transition during the era of degenerative heart diseases has emerged.
CONFLICT OF INTEREST STATEMENT
Dong Zhao is the Associate Editor-in-Chief of Cardiology Plus. The article was subject to the journal’s standard procedures, with peer review handled independently of these Editorial Board members and their research groups.
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