Ischaemic heart disease in China: the time to address rising mortality rates

This editorial refers to ‘Increasing mortality from ischemic heart disease in China from 2004-2010: disproportionate rise in rural areas and elderly subjects’, by X. Zhang et al., on page 47. Ischaemic heart disease (IHD) has become increasingly common in China and has overtaken haemorrhagic stroke in recent years as the country’s leading cause of death.1 Models forecast that the incidence of coronary heart disease in China will rise to over 2.5 million events per year by 2030, which represents a 50% increase over the 2010 incidence.2 Also, in contrast to USA and other developed countries, the mortality rate associated with IHD in China is increasing.3 Efforts to reduce the burden of IHD in China must start with a detailed understanding of the underlying epidemiologic trends. China’s Center for Disease Control and Prevention maintains a disease surveillance system that collects information about causes of death at a nationally representative sample of points.4 In this issue, Zhang et al., using data from this surveillance system, describe national trends in the cause-specific mortality rate for IHD in China between 2004 and 2010. During the study period, the crude IHD mortality rate rose from 70.3 per 100 000 in 2004 to 92.9 per 100 000 in 2010. These data imply an annualized increase in IHD mortality of 4.8%. Prior reports also using data from this surveillance system have indicated that the crude IHD mortality rate grew at approximately 3% between 1990 and 2013,5 thus the analysis by Zhang et al. indicates that IHD mortality rates may be increasing. Comparable trends were evident in the IHD mortality rate after age standardization, using both a standardized national population for China and the World Health Organization’s standard population to facilitate international comparison. Stratified analyses revealed significant differences in IHD mortality rates between patients according to their age, sex, and location. Rates of IHD mortality were particularly high among the elderly, males, and patients living in rural China. The analysis presented by Zhang et al. extends previous studies that have observed similar differences in IHD mortality by describing temporal trends in mortality rates for patients in these subgroups.6 Their analysis suggests that the increase in the overall IHD mortality rate is largely driven by increases in IHD mortality rates among patients from rural China and those aged 80 years or older. Specifically, the incidence rate ratio for IHD death for patients in rural China was at least twice that of patients from urban areas, indicating that IHD mortality rates are growing much more rapidly in rural areas. Similarly, the rate of IHD mortality in patients aged 80 years or older increased by over 50% but was unchanged in all other age groups. Although there is clear evidence that mortality from IHD is rising, it is important to acknowledge the possibility that China’s epidemiologic transition is amplifying the increases in the cause-specific mortality rate for IHD reported by Zhang et al. Improvements in public health and access to health care have driven down the incidence of infectious disease and associated mortality leaving more patients at risk of non-communicable diseases, such as IHD. It seems possible that this effect is particularly pronounced among the elderly and those living in rural areas, meaning that the trends in IHD mortality rates reported by Zhang et al. carefully interpreted. Complementary analyses of trends in other causes of mortality would be extremely helpful in contextualizing the magnitude of this effect on trends in IHD mortality rates. Prevention of IHD and improving outcomes for those with existing IHD should be the overarching goals for efforts aiming to slow China’s rising rate of IHD mortality. The findings of the analysis presented by Zhang et al. suggest that focused initiatives that emphasize the elderly and rural residents, in whom the rate of IHD mortality is rising the most rapidly, may be particularly productive. As age is not a modifiable risk factor and most cardiovascular risk factors develop well before the age of 80 years, quality improvement efforts may be more effective among the elderly. In contrast, prevention and risk factor modification is likely to be a critical lever for reducing IHD mortality rates among patients from rural China where access to health care has historically been limited. Effective primary prevention necessitates a thorough understanding of risk factors for IHD, as well as proven strategies for modifying such risk factors. The associations between IHD and risk factors, such as hypertension, hyperlipidemia, diabetes, and smoking, were initially established through large-scale epidemiology studies in Western populations; however, these associations require confirmation in the Chinese population. The China Kadoorie Biobank group has made significant progress on this front and has confirmed strong associations between cardiovascular mortality and both diabetes and smoking,7,8 and it has also detected an interesting association between fresh fruit consumption and lower cardiovascular mortality.9 Similarly, although there is clear evidence that IHD can be prevented by risk factor modification with medications, such as antihypertensives and statins, and behavioural interventions, such as smoking cessation counselling, these interventions have been studied primarily in Western populations, so the magnitude of their benefit in China requires clarification. Improved diagnosis and treatment of IHD risk factors will be important as studies have indicated that IHD risk factors are often underdiagnosed and uncontrolled.10,11 The recently launched China PEACE Million Persons Project will test a rapid screening strategy for cardiovascular risk factors that will provide additional information about the epidemiology of IHD and may enable primary prevention strategies to be tested.12 China must also attempt to improve the outcomes of care for the rapidly growing population of patients who have or will develop IHD. A nationally representative study revealed that there has been little change in in-hospital mortality for patients treated for ST-segment myocardial infarction in China’s hospitals from 2001 to 2011.13 If China is to reverse its rising IHD mortality rate, it must improve the quality of care provided by hospitals for IHD, not only by investing in new technology but also by using existing resources effectively.14 Although rates of IHD mortality in China are similar to those of developed countries,15 IHD mortality is growing quickly in China, while it is falling sharply in many developed countries. In fact, gains have been achieved in USA despite apparently unfavourable epidemiologic trends: patients in USA experiencing acute myocardial infarction are older and have an increasing number of comorbidities yet mortality is falling,3 a finding that suggests that improvements in quality have played an important role. Drivers of falling IHD mortality in developed countries include improved awareness and diagnosis of acute coronary syndromes, timely provision of reperfusion therapy (in particular primary percutaneous coronary intervention), and appropriate use of medical therapy for secondary prevention. China may be able to learn from the experience of developed countries to ease the growing burden of IHD. The growing incidence of IHD in China combined with the recent uptick in the IHD mortality rate indicates that morbidity and mortality due to heart disease will grow in the coming years. To slow this rising tide of IHD, heart disease must be prevented and the quality of care provided to those with IHD must be improved. Since recent increases in the IHD mortality rate appears to be somewhat concentrated in rural China and the elderly, prevention and quality improvement efforts emphasizing these groups seem to have particular promise. The sheer size of China means that the scale of the challenge is massive; however, if China can successfully reverse the rise in IHD, countless lives will be saved and the country will become a model that many others will follow. Conflict of interest: none declared.