Globally, a third of deaths can be attributed to CVD, while TE is the major contributor and causes approximately 3 million cardiovascular deaths per year . In 2019, WHO reported estimates for the prevalence of smoking in all countries in response to the global tobacco epidemic . From the report, it is found that China has the highest smoking prevalence compared to the other three regions in this study. Meanwhile, the smoking prevalence decline was smallest in China and the country has the highest level of exposure to second-hand smoke. Due to the possibility of TE, sex is an important demographic risk factor for CVD . From the results in this study, it is found that the mortality rates of CVD, IHD, and stroke attributable to smoking and SHS were similar for both sexes. It is suggested that males were the primary victims from smoking, while women were the primary victims from SHS.
The results show a significant downward trend in ASMRs for CVD attributable to smoking from 1990 to 2017 in the four regions studied. Compared to the world, the ASMRs of CVD, IHD and stroke attributable to smoking had the biggest decline in the USA and Japan, while China had the smallest rate of decline from 1990 to 2017. It is found that in China, the ASMRs of CVD and IHD attributable to smoking became the highest in 2017, while the ASMR of stroke continued to be highest in China from 1990 to 2017. All the ASMRs of CVD, IHD, and stroke attributable to smoking in China were higher compared to the world, and the ASMRs of CVD, IHD, and stroke attributable to smoking in Japan and the USA were lower than those in the world. For SHS in China, the ratio of SHS to smoking in the ASMR of CVD ranged from one-quarter to one-third in the period 1990 to 2017. Compared with the other three regions, SHS exposure had caused a serious CVD burden in China. One study on SHS found that non-smoking women married to husbands that smoke had an almost 40% increased mortality risk, while the incidence of heart disease also increased . A national population-based case-control study found that SHS can increase the risk of death by 10% for all forms of strokes by adjusting for related variables . In 2017, the researchers also found all the ASMRs of CVD, IHD, and stroke attributable to SHS in China were higher than those in the world, while the results for Japan and USA were the reverse.
In 2017, the researchers found that China had the highest levels of ASMRs of CVD, IHD, and stroke attributable to TE. This may be due to when tobacco control measures were implemented. Tobacco control is a global health priority for non-communicable diseases. The USA and Japan started tobacco control relatively early compared to the world, while this only happened later in China . The WHO Framework Convention on Tobacco Control (FCTC) was formalised global commitment by 180 countries and began to be implemented in 2005 . The United States Congress passed the Federal Cigarette Labelling and Advertising Act and the Cigarette Act in 1965 and 1969, respectively. The Family Smoking Prevention and Tobacco Control Act, which passed in 2007, was stricter than FCTC . In Japan, tobacco control started later than most developed countries. In 1978, a non-governmental movement for tobacco control was launched, and in 1985 the tobacco monopoly system was reformed . In 2010, tax on cigarettes was raised by a large amount. China signed FCTC, which came into operation in 2006. China implemented restrictions on the packaging, advertising, and ingredients of tobacco products, for instance one cigarette with 15mg of tar would be regarded as an unqualified products and not be allowed to enter the cigarette market .
In APC analysis, the longitudinal age curve reflects the impact of age on the mortality rate of disease. In this study, the longitudinal age curves of the mortality rate of CVD, IHD, and stroke attributable to smoking increased by age in China, Japan, the USA, and the world, with this increasing in China more than the other regions studied. Before age 60, the morality rates of CVD, IHD, and stroke attributable to smoking were at lower levels with slight differences in the four regions, but they became wider after the age of 60. In each age group, the morality rates of CVD, IHD, and stroke attributable to smoking were lowest in Japan. Similar results were also found for the mortality rate of CVD, IHD, and stroke attributable to SHS. Age is an important factor for CVD, and the results in the present study could be due to two reasons: First, long-term TE results in vascular damage; second, physical resistance declines with age . In China, it is suggested that the elderly should be listed as key persons in the prevention and treatment of CVD, basic public health services should be optimised for them, and the screening and management of the elderly should be performed well.
In four regions, the period RRs indicate a downwards trend in the mortality rate of CVD attributable to smoking from 1990 to 2017. Similarly, the cohort RRs also indicate a downwards trend in CVD mortality from births in 1910 to births in 1990. China is found to have experienced the smallest decline in the cohort and period RRs, while the cohort and period RRs in females declined faster than for males. The changes of the period and cohort RRs for stroke were similar to CVD, while IHD was found to be little different from CVD. While the period and cohort RRs indicate a down trend in the USA, Japan, and the world, these fluctuated in China. In the four regions, all the net drifts were significant and below zero, with the exception of the net drift of IHD in China. All the SHS results are similar to those for smokers, while the results for males and females are also similar. Compared with the USA, there were significant differences in the morality pattern of CVD in China, since the proportion of stroke was higher, the proportion of IHD was lower, and the morality pattern of CVD in China was similar to Japan . Similar patterns are also identifiable in Tables S3 and S4. Due to improvements to medical conditions in China, increased public health funding, and the early diagnosis and treatment of noncommunicable diseases such as CVD and cancer, the occurrence and death of CVD has been effectively controlled. In particular, there have been significant improvements in stroke mortality, which could be due to more attention paid to strokes due to its prevalence. But the results reflect that the downwards trend in the mortality rate of IHD is not obvious. Through comparison, it is found that the mortality rate of IHD decreased in the USA, where IHD is the main component of CVD. Meanwhile, the mortality rate of IHD also decreased in Japan with a similar CVD composition to that of China in which IHD was not the main component of CVD. Based on China’s actual situation, China should learn from these two countries to explore appropriate measures for CVD and tobacco control.
A number of limitations are identified in the present study. First, GBD 2017 underwent many modifications and adjustments to its data sources, collation, and evaluation methods to fulfil missing data and improve its data quality and comparability, but it is still difficult to avoid bias. Therefore, the integrity and accuracy of the data in the present study was affected. Yet using the GBD database to show the long-term trends minimises the adverse effects, meaning that the bias from the GBD database will not have an intolerable impact to the present study and barely affects the changes to the long-term trends [29-31]. Second, the APC model only regards population as the unit of observation and analysis, which could lead to ecological fallacy. Therefore, the results of this study must be further confirmed by future research. Third, the researchers only estimated the effects of age, period, and cohort on the CVD mortality data attributable to tobacco exposure, while no further analysis was conducted on other risk factors.