Tackling the challenge of cardiovascular disease burden in developing countries Salim Yusuf, DPhil, FRCPC,a Mario Vaz, MD,b and Prem Pais, MDb Hamilton, Ontario, Canada, and Bangalore, India
See related article on page 7.
The last century has witnessed the rise and a partial fall in the rates of cardiovascular disease (CVD) in most Western countries. The rise in CVD coincided with increasing industrialization and urbanization, which were associated with increasing levels of dyslipidemia, blood pressure, and diabetes.1,2 Concurrently, there has also been an increase in the rates of tobacco consumption in several countries. After reaching a peak around the 1960s to 1970s, the CVD rates started to decline in several Western countries, perhaps due to aggressive policies to curb tobacco use, increased awareness by both physicians and lay people that CVD is preventable, the identification of methods for controlling risk factors, and effective strategies for secondary prevention. It has been, therefore, a combination of obtaining reliable data on incidence and prevalence of CVD, research that has identified both risk factors and the demonstrable value of modifying them, and public health policies and awareness that has stemmed the tide of CVD in developed countries. A half century later, it is now recognized that the epidemic of CVD has shifted to middle-income and low-income countries (collectively termed developing countries in this article), so that about 80% of the global burden of CVD currently occurs in these countries.1 It is likely that this epidemic is fuelled by similar societal and biologic factors globally. With increasing industrialization and urbanization worldwide, 2 major lifestyle changes are occurring. First, with increased automation at work and at home, sedentariness has increased, leading to marked reductions in energy expenditure. Second, a nutritional transition to increased energy consumption (especially to foods high in saturated fats and refined carbohydrates) is transforming food consumption globally. These 2 lifestyle changes, occurring across the whole spectrum of societies (es-
From the aPopulation Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Ontario, Canada, and the bPopulation Research Institute, St. John’s Medical College, Bangalore, India. Reprint requests: S. Yusuf, Population Health Research Institute, Hamilton General Hospital, 237 Barton St. East, Hamilton, Ontario L8L 2X2. E-mail: [email protected]
Am Heart J 2004;148:1– 4. 0002-8703/$ - see front matter © 2004, Elsevier Inc. All rights reserved. doi:10.1016/j.ahj.2004.03.045
pecially urban), are probably the root cause of increasing rates of obesity, diabetes, elevated lipids, and elevated blood pressure (BP) levels. Combined with high rates of tobacco consumption, all the ingredients for a dramatic increase in CVD are set. So what can be done about this looming pandemic? First, there is an urgent need to better document the current rates (incidence and prevalence) of CVD mortality and morbidity in—at least—the large developing countries of the world (eg, China, India, Brazil, etc), as well as in some representative countries in several other regions of the world (eg, Middle East, Eastern Europe, and Latin America). In many countries, reliable mortality statistics, especially by cause of death, are not available, and in most developing countries, representative data on morbidity (eg, non fatal vascular events) and risk factors are not available. Data on morbidity and risk factors over time from “sentinel sites” (representing geographically diverse locations, including rural and urban populations and different socioeconomic classes) are urgently needed. This will allow accurate assessment of current disease burdens, as well as allow reliable projections of the future course of the CVD epidemic. Second, while data on the importance of risk factors for CVD are being generated from developing countries, it would be reasonable to extrapolate from studies conducted in Western countries to formulate strategies for prevention. Such strategies, including tobacco control programs, BP control, lipid lowering, as well as the promotion of healthy lifestyles (increased consumption of fruits and vegetables, along with regular physical activity), could be the cornerstone of a global program for prevention. Such strategies are best applied taking into account local economic and social circumstances, with emphasis being placed on risk factors that are common in particular populations. Third, societal-level strategies that include healthoriented agricultural, food, and tobacco policies are essential (as the roots of CVD are probably embedded within an unhealthy societal environment). Food policies that increase the availability of low-cost fresh vegetables and fruits would likely increase their use. While many countries have promulgated some tobacco control policies, enforcement is lax and there are several local barriers to its success that differ from Western countries. For example, the 2 countries with the largest tobacco production are China and India.3 In
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China, the largest tobacco manufacturer is the government. In India, beedies (unprocessed tobacco in a temburni leaf) account for 54% of tobacco use, with cigarettes being 19% and various forms of smokeless tobacco forming the remaining 27%. The beedi industry is a major source of economic sustenance for large parts of the rural population in several states in India and is estimated to employ about 12 million individuals, most of whom are poor. While taxation of cigarettes (an organized industry) and health and safety warnings on packets have been implemented in India, these policies have not been applied to beedies, which are largely produced by the nonorganized sector and are therefore difficult to regulate. Moreover, while cigarettes are relatively expensive (about Rs. 60 for a pack of 20, or US $1.30), a similar number of beedies cost a mere Rs. 3 (or about 8 cents). Implementing an effective tobacco control policy requires major policy and political strategies which include changing the economic base for several tens of millions of low-income individuals engaged in tobacco cultivation and beedi production to alternative agricultural and economic activities. Uncontrolled growth of cities and urban sprawl in developing countries has led to long commutes for workers by buses or trains, thereby decreasing usual physical activity. Additionally, encroachment of public spaces (parks, playing fields, walking paths) in the interests of commercialization has decreased opportunities for leisure time physical activities. There is an urgent need for urban planners in developing countries to ensure the retention of public spaces, as well as to consider planning cities that encourage physical activities, for the future health of their populations. In parallel, the school curricula in many countries have increased emphasis on classroom instruction with little or no emphasis on physical activity or sports. This imbalance promotes sedentary behavior and obesity in children. Therefore, obesity rates among adults in developing countries are likely to be higher in the future. Fourth, there is an urgent need for large-scale epidemiologic and clinical research to provide local answers to the challenges faced in tackling the CVD epidemic in individual societies. As initial steps, case-control studies in multiple countries (such as the INTERHEART Study, which involves 52 countries) will provide preliminary information on which to base preventive strategies.4 However, prospective cohort studies in different regions of the world are needed. In particular, such studies should document societal, cultural, and economic factors that influence lifestyles— especially nutrition and physical activities. Food patterns vary enormously and the common diet consumed by individuals in urban settings in some countries (eg, India) has a level of fat intake that is substantially below the recommendations formulated by the Western
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bodies such as the AHA (AHA-Step II), yet is significantly higher than that consumed by their counterparts in rural areas where CVD rates and risk factors are low. Related to this are cultural norms about body image, which are influenced by centuries of inadequate food availability. Consequently, in some parts of the world, a lean body is perceived to be a sign of illness or poverty, whereas being overweight may be considered a sign of good health and affluence. In India, food policies and subsidies from governments (which include the provision of polished rice at low prices) has led to the replacement of traditional whole grains (high fiber content) with polished cereals (low fiber content). Therefore, in order to develop rational strategies for lifestyle change, awareness of local cultural factors that affect patterns of food intake and activity as well as an understanding of the impact of government policies are essential. A key risk factor in most epidemiologic studies has been measurement of body weight (such as by use of the body mass index [BMI]) as an index of adiposity. This index has been derived from Western populations and its applicability to other populations is unclear. Several studies have indicated that for the same BMI, Asian populations have higher levels of body fat.5 Moreover, in some studies BMI has not been predictive of CVD in Asian populations.6,7 Therefore, alternative measures of adiposity are required that are predictive of CHD (eg, waist-to-hip ratio) and that can be applied to multiple ethnic groups. Fifth, few centers in developing countries have the necessary infrastructure or the expertise to conduct large-scale epidemiologic research studies and clinical trials. A culture of research does not exist among most medical schools in developing countries, and few countries have national bodies that provide funds for studies. Where they do exist, an absence of clear guidelines, lack of timelines for reviews, long delays between submission of grants and funding (often of several years), and a lack of transparency raise additional challenges for investigators. Many of the international bodies that fund health research in developing countries (the Gates Foundation, among others) focus their priorities on infectious diseases. Although this is understandable (given the large burden of infectious diseases in developing countries), increasing recognition of the problems of CVD, diabetes, obesity, and other chronic diseases in developing countries should prompt a more balanced approach to priority setting and funding. Sixth, while most secondary interventions (such as aspirin, ␤-blockers, lipid-lowering agents, angiotensinconverting enzyme inhibitors, etc) have been evaluated in trials conducted in European populations, there are practically no data among Asians, Arabs, or Africans. However, it would still be reasonable to extrapo-
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Table I. Strategies to effectively tackle the growing problem of CVD in developing countries 1 Development of reliable statistics on mortality, morbidity and risk factor levels in multiple developing countries (eg, through sentinel surveillance programs). 2 Utilize available information on the importance of conventional risk factors (tobacco smoking, high BP, elevated lipids etc) to develop strategies for prevention in developing countries. 3 National policies on agriculture (to make fruits and vegetables more affordable and promote the consumption of whole grains), urban planning (to promote physical activity during daily life) and effective tobacco control. 4 Large scale epidemiologic studies to document societal and individual factors influencing lifestyles, and how these relate to risk factors and CVD. 5 Developing research capacity for investigating the determinants and modifiers of chronic disease such as CVD, obesity and diabetes. Strengthening and improving the efficiency of existing national funding bodies for research. Raising the priority of chronic disease (including CVD), as being worthy of research funding by national and international organizations. 6 Encouraging and documenting the use of simple secondary prevention measures through registries and improving optimal prescribing though physician education programs. 7 Ensuring that proven therapies are affordable to those with CVD or for those with CV risk factors. 8 Raising awareness among the public of the health hazard of smoking, physical inactivity and diets high in saturated fats and a high glycemic load.
late the findings to other populations worldwide. The World Health Organization has, since 1999, begun to develop protocols for prevention of CVD in the developing countries. Collaborative registries of common conditions (eg, acute coronary syndromes, heart failure, strokes, valve diseases) in multiple centers will assist in documenting current practices, factors influencing treatment decisions, and how these change over time. This will generate interest in ensuring that treatment practices follow accepted guidelines. Clinical trials of low cost and affordable interventions such as glucose insulin potassium in acute myocardial infarction are urgently needed. The concept of the development of a low cost “poly-pill” (incorporating a diuretic, aspirin, statin, ␤-blocker and an angiotensinconverting enzyme inhibitor) could form a useful part of national programs.8,9 Seventh, unique challenges related to the social and economic circumstances of developing countries should be noted. Most developing countries suffer from a “double burden” of disease: they have high rates of mortality and morbidity resulting from undernutrition and childhood and infectious diseases, while simultaneously experiencing growing rates of chronic diseases. Therefore, there is a need to maintain an infrastructure that can deal with a broader range of prevention and treatment services in developing countries, which differs from that generally needed in most
Yusuf, Vaz, and Pais 3
Multilevel integrated strategies for the prevention of CVD. The size of the box approximates the relative size of the population impact.
developed countries (where the burden of infectious disease is much lower). This double burden is set against a background of low economic circumstances and poverty, meaning there are severe limits to the availability of prevention programs and access to therapies considered proven and relatively inexpensive in several developed countries. Therefore, affordability of simple treatments (eg, some blood pressure lowering drugs or statins) that require lifelong use may pose financial hardship to a laborer (earning US $1–$2 per day or less in some countries in Africa and South Asia), even at prices considered to be low by international standards. (For example, the monthly cost of certain medications in India are the following: 25 mg of hydrochlorothiazide, 70 cents or 35 rupees; 20 mg generic Enalapril, Rs. 195 or US $2.70; 10 mg generic Atorvastatin, Rs. 220 or US $3.90.) Not surprisingly, long-term adherence to medications (especially multiple) is probably poor. The situation is probably worse in other countries (eg, Pakistan) where drug prices are relatively high (about 2- to 3-fold higher than India). While the idea of a low-wage laborer requiring therapy for CVD seems counterintuitive, there is already evidence of increasing levels of obesity, dyslipidemia, and diabetes among slum/shanty-town dwellers in developing countries. The problem of affordability of drugs in developing countries is likely to become more severe, as several multinational pharmaceutical companies have adopted a policy of “global pricing” (where prices in all countries, including developing countries, are pegged to the median price in G7 countries). This will almost certainly make most new drugs unaffordable to the vast majority of patients worldwide with CVD. It is hoped that this pecuniary policy will be short lived, and sensibly modified, so that drugs will be marketed in various countries at prices that reflect local purchasing power in each country. If not, the majority of patients with CVD in developing countries
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(and therefore the world) will not benefit from several of the advances in science and medicine. In summary, despite the imperfections of the available data, the current situation demands a concerted and urgent global effort to prevent and manage the rising epidemic of CVD in developing countries. Such an effort should be multipronged: based on the application of current knowledge for modifying risk factors and secondary prevention, in a manner sensitive to the social, economic and cultural circumstances of each country. To be effective, there is a need for cooperation and coordination of efforts among policy makers, governments, urban planners, national professional societies, physicians and other health workers, research funding bodies, the pharmaceutical and related health industries, and society at large (Table I). Although the challenge is formidable, there is no alternative but to meet it with a cohesive multilevel strategy (Figure 1).
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