‘The challenge of the cardiovascular disease epidemic is not whether it will occur at all in the developing countries but whether we respond in time to telescope the transition and avoid the huge burden in young and middle age adults. The question is not whether we can afford to invest in cardiovascular disease prevention in the developing countries, but whether we can afford not to’ (Ruth Bonita).
This statement by the director for the surveillance of non-communicable diseases at the World Health Organization (WHO) forcefully summarizes critical issues related to cardiovascular disease (CVD) in developing countries: the upsurge of the CVD epidemic and the need for an urgent response to prevent an impending additional burden that can hardly be afforded by low and middle-income countries already plagued with scarce resources and a large burden of infectious diseases. Global–regional–local interrelations are central to these considerations. Globalization fuels the epidemic even to the remotest communities by spreading many unhealthy behaviours and environments conducive to CVD. However, globalization can also provide powerful means to tackle CVD at broad and local levels.
The rise in CVD in developing countries can be best understood in the light of the ‘epidemiological transition’ (Omran 1971; Reddy & Yusuf, 1998), an evolutionary framework linking demographical and social change to disease patterns. The rapid ageing of populations in developing countries is the first engine in the emergence of CVD. This demographic transition results from improved sanitation, nutrition and infectious disease control, particularly in childhood, which accompany urbanization and industrialization. Prolonged survival allows for longer exposure to CVD risk factors and this inevitably results in larger total numbers of CVD cases. In addition to ageing populations, industrialization and urbanization also bring about several changes in lifestyles such as sedentary habits, tobacco use and unfavourable dietary patterns, which further increase the incidence of CVD and other chronic diseases. While the mix between specific chronic diseases in populations, particularly cerebrovascular disease and ischaemic heart disease, can differ substantially between developing countries, the shift from early transition diseases (infections and malnutrition) to late transition diseases (CVD and other chronic diseases) is rapid, large and consistent among most developing countries (Yusuf et al. 2001a, b).
It is not often appreciated that the current CVD burden in developing countries is already high. Approximately 78% of the burden of non-communicable diseases and 85% of the cardiovascular burden worldwide arose from the low- and middle-income countries in 1998 (WHO 1999). Furthermore, the CVD burden is expected to further increase significantly over the next decades. The combined morbidity and mortality burdens (expressed as disability-adjusted years of life lost) caused by ischaemic heart disease and cerebrovascular disease in developing countries are anticipated to rank first and fourth in 2020, comparedwith sixth and seventh in 1999 (WHO 2000a, b). It is also often not realized, possibly because of very high mortality rates from other diseases, that age-specific death rates from non-communicable diseases are higher in developing than developed countries (Murray & Lopez 1996). For example, the probability of stroke death is several folds higher, at all ages, in Tanzania than in the UK (Walker et al. 2000).
A number of factors could exacerbate the CVD epidemic in developing countries compared with its course in western countries. Urbanization in settings of poverty differs from that which occurs in prosperous economies, and the vulnerability to unhealthy behaviours is likely to be increased in a context of loose social network, stressful waged labour and restricted resources for public health response. This points to the higher prevalence of CVD and CVD risk factors among people of low socio-economic status – as we found for example in Tanzania (Bovet et al. 2002). An anthropological view suggests that high prevalence of some risk factors in population subgroups (e.g. hypertension in urban settings) can express a human maladaptation in an affluent society due to a dissonance between modern culture and the evolutionary legacy (i.e. an ‘acculturation’ process) (Dressler 1999). A gene–environment interaction has been postulated (the ‘thrifty genotype’ hypothesis) whereby CVD risk factors (e.g. obesity, diabetes, ‘diabesity’) would be the result of an evolutionary advantageous thrifty genotype that promotes fat deposition in times of plenty (Neel 1962). A foetal programming hypothesis postulates that intrauterine malnutrition (reflected by a low birth weight) leads to permanent biological structure and function changes that pre-dispose to CVD in adult life (Barker 1995).
Although the population-attributable importance of different risk factors can vary substantially between populations, the proximal causes of the CVD epidemics are qualitatively similar in all populations (van den Hoogen et al. 2000). Some major factors – physical inactivity, tobacco use and inappropriate diet (as expressed through unfavourable lipid levels, overweight and elevated blood pressure) – explain as much as 75% of the occurrence of CVD (Magnus & Beaglehole 2001). In the absence of these main risk factors, CVD is a rare cause of premature death (Stamler et al. 1999). Importantly, experience in a variety of populations has consistently demonstrated that lowering BP, blood cholesterol and quitting smoking greatly reduce CVD occurrence and numerous well-conducted trials have shown the importance of lifestyles and diet for improving risk factor levels and CVD outcomes (de Lorgeril et al. 1999; Sacks et al. 2001; Tuomilehto et al. 2001). From a strategic perspective, it must be recognized that interventions targeting only high-risk individuals (e.g. hypertensive or diabetic patients) will have very limited impact on the total CVD burden at the population level because most CVD cases in a population arise from the many individuals who have only moderately elevated risk factor levels – the so called ‘prevention paradox’ (Rose 1981). Population-wide intervention makes sense: it is estimated that a reduction in diastolic BP of only 3 mmHg in the entire population would reduce stroke deaths by about 1 million in the Asia/Pacific region by 2010 (Eastern Stroke and CHD Collaborative Research Group 1998). Overall, enough knowledge is now available for rational and effective prevention and control of CVD, even in developing countries (Beaglehole 2001).
The rapidly escalating prevalence of risk factors in many developing countries points to several detrimental effects of globalization. Globalization can be characterized by intensified human interactions in a wide range of spheres (social, political, economic, environmental). The formidable spread of communication technologies has brought about an unprecedented flow of information across geographical, political and cultural boundaries via the mass media, advertising agencies and electronic channels. Unleashed trade liberalization has resulted in profound changes in consumption patterns worldwide, which parallel a concentration of the food production and expanded markets at an intercontinental scale. Remarkable examples of increased consumption of unhealthy products resulting from global marketing campaigns and trade liberalization include cigarettes, carbonated drinks (‘coca-colonization’) and cheap energy dense foods – the latter replacing locally produced low-fat and fibre-rich foods. In this respect, CVD can be appropriately considered as a communicated disease. By fuelling ‘vectors’ that can alter people's lifestyles, particularly with regards to tobacco use and unhealthy dietary patterns, globalization is certainly an important factor for the increasing prevalence of overweight, high blood pressure, dyslipidaemia, type II diabetes, and ultimately CVD.
However, globalization also offers a range of potentially powerful opportunities for improving public health, including the prevention of CVD. On a general note, globalization can benefit health through improved economic growth and incomes, including the poor (Feachem 2001). More specifically, electronic information technologies permit expeditious and inexpensive dissemination of evidence-based knowledge to individuals, health professionals and policy-makers. This provides unprecedented opportunities for training in the remotest places and it facilitates network-building and information-sharing at regional, national or international levels. Global mechanisms can also be created to counter transnational political or economical influences. An example is the Framework Convention for Tobacco Control (FCTC), which is currently being drafted by the member states of the WHO. This legally binding international treaty will be a powerful global public health instrument for improving and harmonizing tobacco control measures and legislations in most countries. The ‘power of the process’ of negotiating this global treaty is already galvanizing new mechanisms of multisectoral collaboration at both national and continental levels. The influence of globalization on trade can also be positive. In Hungary, liberalization of trade in 1989 (alongside an unchanged health budget) resulted in substantially improved dietary patterns (e.g. fewer animal products and more fresh fruit and vegetables) that are believed to have largely accounted for the 25% decrease of the CVD mortality from 1989 to 1995 (Zatonski et al. 1998).