In 2019, CVD accounted for approximately 35% of total deaths in Asia, causing 10.8 million fatalities and making it the leading cause of death in the region [5]. However, the age-standardized CVD mortality in five Asian countries shows a decreasing trend over time, especially during the period from 2003 to 2008, with the largest decline observed in South Korea (37.47% decline) and the lowest in China (7.29% decline). From 2015 to 2020, South Korea had the highest decrease (30.36% decline), while Taiwan had the lowest (1.01% decline). The age-standardized CBD morality also showed a similar downward trend over time. Whereas the growing crude CVD mortality rates indicated the increasing burden of CVD in Asian populations. In addition, the fall in age-standardized CVD mortality implied that the trend in the crude mortality rate was driven mainly by the growing aging population and medical service changes [3]. However, there was no similar trend in hypertension. Singapore had the largest decrease in hypertension (105.33% decline) from 2003 to 2008, followed by South Korea (86.0% decline), while Taiwan and China showed an increase (33.93% and 18.64%, respectively). From 2015 to 2020, Japan showed an increase of 20.00%. Diabetes had a decreasing trend over time, but the magnitude of the decrease varied across countries, with the largest decrease in China and the lowest in Taiwan. Although both hypertension (HP) and diabetes mellitus (DM) are risk factors for CVD and CBD, the results showed that the SMRs (standardized mortality ratios) of HP and DM did not contribute much to the mortality rates of CVD and CBD. This might be due to the changing trends in mortality rates over the years with competing causes of death. It could be also due to the fact that this study measured indicators as SMRs, not incidence rates, and susceptible to the influence of the medical level of each country and other risk factors, such as lifestyle and economic conditions. Of note, China has higher age-standardized CVD and CBD moralities than other countries, possibly due to its aging population trend. In China, the incidence and mortality rates of CVD and CBD are generally higher in older people, which is one of the main factors affecting China's CVD and CBD mortality rates. In addition, Chinese dietary habits, lifestyle, and environmental factors all have significant impacts on the incidence and mortality rates of CVD and CBD. For example, Chinese people have a higher intake of salt, a higher rate of obesity, and a lack of exercise, which are factors that contribute to the incidence and mortality rates of CVD and CBD. The risk of CVD shows geographical variation in China, with higher rates observed in the northeast (12.6% [12.4-12.8]) and north China (11.4% [11.3-11.6]), while lower rates were found in the south part of the country (8.0% [7.8-8.2]). Possibly, the primary risk factors contributing to CVD vary across different regions of China [10]. In addition, China's healthcare system and resource distribution may also contribute to higher CVD and CBD mortality rates. Particularly, in remote and impoverished areas, medical services and conditions are relatively poor, leading to insufficient early diagnosis and poor treatment of CVD and CBD, increasing the risk of death. Given the geographical variation in CVD risk factors and prevalence in China, it is important to implement targeted interventions in specific regions to mitigate the risk and reduce the burden of CVD in this vast country. As China is currently in a stage of economic development, it is even more important to take preventive measures against CVD-related diseases. As for Taiwan, the SMR of hypertension and DM is higher than that of the other four Asian countries, which is a warning. Since hypertension and DM are common chronic diseases in Taiwan, their prevalence and incidence are relatively high. The lifetime prevalence rates of hypertension and DM in Taiwan are between 25-30% and 10-15%, respectively. With factors such as population aging and unhealthy lifestyles, the incidence of these diseases is increasing. According to data from the National Health Agency of the Ministry of Health and Welfare, the annual incidence of hypertension in people over 50 years old is approximately 3%, while the incidence of diabetes is about 1-2%. Therefore, the prevalence and incidence of hypertension and diabetes are important public health issues in Taiwan. Preventing and treating these diseases requires the active participation of individuals and communities to change unhealthy lifestyles, such as reducing salt intake, controlling weight, and increasing exercise, as well as actively treating and managing these diseases.

This study showed that the proportion of CBD in all CVD varies among countries. Most CVD deaths (87%) were due to ischemic heart disease (IHD, 47%) or stroke (40%). South Korea has a proportion of approximately 35.97% to 61.13%, which has been decreasing annually. Singapore has the lowest proportion, ranging from only 19.85% to 30.61% over time. The other three countries have relatively high proportions, while Taiwan decreased from the highest 41.92% to 25.33%. In 2011, there was a peak of around 47%, indicating significant differences among countries in the proportion of CBD in all CVD over the years. The reasons for this may be related to the following factors: 1. Population structure: Countries with a higher proportion of elderly people have a higher incidence and mortality rate of CVD and CBD. 2. Medical level: Differences in the allocation of medical resources and medical level may affect the prevention, diagnosis, and treatment of CVD and CBD. Countries with more developed medical resources and technology can detect and treat CVD and CBD earlier, resulting in a relatively lower proportion of CBD in all CVD. 3. Disease management and prevention: Different countries have different disease management and prevention strategies, especially for high-risk groups, such as regular screening and management, to reduce the incidence and mortality rate of CVD and CBD.

In addition, there are significant differences in the proportion of CBD to all CVD between Asian and Western countries. In Asian countries, the proportion of CBD to all CVD is usually higher than that of Western countries. For example, in the United States, the proportion of CBD to all CVD deaths is only about 33%. CVD and CBD generally refer to heart, cerebral ischemia, or hemorrhagic diseases caused by various factors such as diabetes, dyslipidemia, hypertension, overweight, or obesity in the United States from 2012 to 2019 [11]. It is worth noting that different studies may use different definitions and methods to calculate the proportion of CBD to all CVD, and these proportions are for reference only. There may be several reasons for the difference between Asian and Western countries. First, different population structures: the population structure in Asian countries is generally younger than in Western countries and the proportion of CBD among young people is lower, resulting in a lower proportion of CBD among all CVDs. Second, differences in lifestyle: people in Asian countries generally have a healthier diet, consume less high-fat, high-salt, and high-sugar foods, and engage in less unhealthy behaviors such as smoking and drinking alcohol, resulting in a lower incidence of CBD. Third, differences in healthcare systems: the distribution of healthcare resources in Asian countries may be insufficient and lead to higher mortality rates of CVDs and CBDs, especially in remote and impoverished areas where medical conditions are poorer. Such limited healthcare resources result in the failure of early diagnosis and treatment of CBD and the increased risk of death. Overall, the proportion of CBD among all CVDs is influenced by various factors, including population structure, lifestyle, healthcare system, etc. Countries should formulate corresponding prevention and treatment measures based on their own situations to reduce the impact of CBD on public health. For example, compared to Western populations, Asian populations tend to have higher sodium intake, lower calcium intake, and lower animal protein intake. Additionally, men in Asian countries tend to consume more alcohol. These dietary differences may contribute to the higher prevalence of hypertension and the increased risk of stroke among Asian countries. As a result, the national chronic disease prevention and control plan reports revealed that Chinese individuals had a good dietary behavior rate of 82%, whereas Koreans and Japanese had rates of 48% and 64%, respectively [12]. Hence, corresponding prevention and treatment measures based on each country’s situation are vital to reduce the impact of CBD on public health.

The risk factors for CVD in Asian countries are comparable to those in other regions, although some factors are more widespread in this area. The major risk factors contributing to the CVD epidemic in Asia are the result of an intricate interplay between socioeconomic and living conditions, demographics, lifestyles, the prevalence of CVD risk factors, and the capacity to achieve prevention and treatment goals. In China, the risk factors for CVD and CBD in young people include obesity, current smoking, atrial fibrillation, hypertension, systolic blood pressure, and total cholesterol, while triglycerides serve as protective factors for CVD and CBD in young and middle-aged individuals [13]. A cross-sectional study showed significant variations in the prevalence of hypertension (24.5% in China, 17.6% in Korea, and 15.2% in Japan) and DM (8.9% in China, 5.7% in Korea, and 4.8% in Japan). Although these countries have made significant progress in modifying risk factors for non-communicable diseases (NCDs) over the past few decades, the prevalence and control of major modifiable risk factors remain concerning (Ma et al., 2017). The age-standardized mortality of hypertension and DM in these countries are not only correlated with their prevalence but also influenced by the sufficient emergency and medical systems in place. As for the risk factors of CVD in other lifestyle factors, including smoking, alcohol consumption, and overweight/obesity, this study could only obtain data on the proportion of alcohol dependence but not historical alcohol consumption habits in the five Asian countries. According to Our World in Data, in 2016, the proportions of alcohol drinkers and heavy drinkers were 55.9% and 40.7% in China, 63.9% and 47.7% in South Korea, 57% and 40.0% in Japan, and 70% and 42.9% in Singapore, respectively. The average monthly alcohol consumption per person was approximately 7.05 liters in China, 9.7 liters in South Korea, 7.96 liters in Japan, and 2.03 liters in Singapore, respectively, indicating that the proportion of alcohol drinkers and alcohol consumption in South Korea is higher than in other three countries. However, information quality needs to be taken into consideration when analyzing the risk factors for CVD in these countries. It should be also noted that this study did not include data on historical alcohol consumption habits, and the proportions and quantities of alcohol consumption may have changed in recent years. In addition, except for Singapore (r=-0.795), the smoking rates in these four countries were positively correlated with CVD mortality, despite efforts to implement national smoking cessation programs. Data from Our World in Data showed that in 1990, among these five countries, the highest smoking rate was observed in South Korea at 29.15%, followed by 28.65% in China, 26.71% in Japan, 25.49% in Taiwan, and 10.29% in Singapore. However, by 2016, Japan had the highest smoking rate at 22.73%, followed by 20.87% in China, 18.63% in South Korea, 12.63% in Taiwan, and the lowest at 7.47% in Singapore. A pooled meta-analysis based on individual participants from 20 prospective cohort studies in Asian indicated that smoking prevalence for men steadily increased in China and India, whereas it plateaued in Japan, South Korea, Singapore, and Taiwan. It also found that lung cancer mortality associated with tobacco smoking continued to increase among Asian men in recent birth cohorts [14]. Based on the report from Global Obesity Observatory indicated that the prevalence rates of overweight and obesity in the four Asian countries were in South Korea at 36.3% and 6.01 [15], followed by 33.07% and 6.51% in China, 22.6% and 4.5% in Japan, and 28.8% and 10.5% in Singapore. In Taiwan, three waves of the NAHSIT data were investigated from 1993–1996, 2005–2008 to 2013–2014, and the prevalence rates of overweight (24≦BMI≦27) (21.5%, 25.5%, to 21.3%), obesity (27 < BMI < 30) (11.8%, 17.9%, to 22.1%) and morbid obesity (BMI > 30) (0.4%, 0.6%, to1.4%) increased sharply in Taiwan. Morbid obesity was found to be correlated with low socioeconomic status and poor dietary patterns. Moreover, the prevalence of obesogenic dietary patterns increased over time in Taiwan [16]. Therefore, further research is needed to better understand the relationship between lifestyle and CVD risk in these countries. Establishing an inter-countries study cohort for CVD and lifestyle is recommended for accurate and up-to-date information [17].

However, our study had some limitations. We noted that correlation did not imply causation and further research is needed to better understand these relationships. Additionally, the specific direction and strength of these correlations may change over time and should be interpreted with caution. Although we tried to standardize our data in different Asian countries as uniformly as possible, some risk factors attributable to CVD in Taiwan had to be retrieved from the governmental survey. However, data representation and accuracy from various sources in international institutions were not promised among the five Asian countries. In addition, different understandings of the definition of lifestyle including dietary behavior, and alcohol drinking that are based on cultural background may also introduce bias into the results. Nevertheless, the trends in the morality from various diseases and their lifestyles may be comparable at different consecutive times in the five countries.

Despite the limitations, owing to the five Asian countries in this study are high levels of economic development, our findings can help governments and healthcare professionals better understand the burden of CVD and CBD mortality and develop effective prevention and management strategies to reduce this incidence of risk factors.

Not applicable.