Exporting failure? Coronary heart disease and stroke in developing countries

The burden of coronary heart disease (CHD) and stroke is considerable, representing 30% of all deaths worldwide, that is about 15 million deaths a year, of which 11 million are in developing or transitional countries.1 Commentators have predicted a global epidemic of cardiovascular disease on the basis of current trends.2 One enthusiast has even stated that ‘In fact, cardiovascular disease is already the leading cause of death not only in developed countries but, as of the mid-1990s, in developing countries as well’,3 a statement not supported by data in the World Health Report 2000.4 Citing statistics in this way undoubtedly fuels the view that ‘something must be done’, promulgated by bodies such as the World Heart Federation.1 Clearly the absolute numbers of deaths should be related to the population at risk, which is substantially greater in developing countries of the world. The Global Burden of Disease study has attempted to provide a picture derived not only from mortality data but also from cardiovascular disability, some of which is consequent upon diseases other than coronary heart disease and stroke.5 This study demonstrated that while ischaemic heart disease and stroke were 5th and 6th in the 1990 league table of disability adjusted life years (DALYs), they contributed 20.4% of the DALYs in developed countries, but only 8.3% in developing countries.6 Concerns about the accuracy of international mortality data and the virtual absence of relevant incidence and disability data clearly need to be addressed urgently if the approach is to have validity.7 Epidemiological studies in developing countries, although small in number, provide evidence that stroke mortality rates tend to be higher than coronary heart disease rates,8 and may be considerably higher than in developed countries,9 but both stroke prevalence10 and coronary heart disease prevalence11 are considerably lower, which may reflect more severe disease or worse health services, leading to higher case-fatality rates. The World Health Organization MONICA surveys, while dominated by developed countries, have data from China which experienced the lowest coronary heart disease event rates of any MONICA centre, but one of the highest annual relative increases among men, but not women.12 Adverse risk factor changes in Chinese men, but not women, were associated with the increased male event rate.13 Surveys of cardiovascular risk factors in developing countries tend to show lower mean levels of blood cholesterol, blood pressure and body mass index; although urban levels may be closer to those found in developed countries.10,14,15 Smoking in developing countries is of growing concern as consumption in the developed world tends to contract, but manufacturers’ cigarette production and profits increase markedly.16 Of the 1.1 billion smokers worldwide, 800 million live in developing countries—with 300 million in China. It is to be expected that the cardiovascular disease consequences of smoking will be increasingly felt as these comparatively young smokers age.17 It has been estimated that current smoking uptake rates in China will result in 100 million deaths among the 0.3 billion men aged now under 30 years, with half of these deaths occurring in middle age.18