Cardiovascular disease and global health: an overview of a major “neglected disease”
Joshua Schulman-Marcus discusses the global burden of this disease
Cardiovascular disease is the leading cause of mortality in almost every developing country in the world. This under-recognized epidemiological reality is true in both low-income countries such as India and Pakistan as well as middle-income countries such as Mexico and Russia (1); the notable exception is several countries in sub-Saharan Africa that are predominantly afflicted by HIV/AIDS. (1)
Cardiovascular disease (CVD) has many symptomatic manifestations, notably ischemic heart disease, myocardial infarction (heart attack), or congestive heart failure. Related disease entities, each aggravating CVD and causing additional morbidity and mortality, include diabetes, cerebrovascular, renovascular, and peripheral vascular diseases. (2) Even though 80% of the global CVD burden is already in developing countries, we can expect that CVD prevalence will continue to increase as many developing countries advance economically and shift towards an urban, aging population with greater lifestyle risk factors. (3,4)
Epidemiological Myths
Despite the known and growing impact of cardiovascular diseases in developing countries, epidemiological data at the country level is generally of poor quality. Most data are derived from global estimates of disease burden and risk factors. (1,2) For example, a brief search through the recently-initiated WHO Global InfoBase (a databank of chronic disease prevalence and risk factors) reveals that most developing countries have little to no population-level information or disease surveillance systems. (5)
However, emerging research is challenging many widespread notions about the disease in developing countries. For example, while CVD is more common in urban areas, an Indian study found it increasingly in rural areas as well. (6) Even though CVD prevalence is still higher among wealthier socioeconomic classes, the majority of the disease burden actually falls on the poorest members of society. (4) The poor are less likely to receive preventive care and are more likely to die from acute manifestations of CVD such as myocardial infarction and stroke. (7) Furthermore, the true prevalence of CVD among the poor is likely under-estimated, as they are far less likely to be diagnosed or treated. (8)
Significantly, the disabilities of chronic CVD can cast households into poverty. If ischemic heart disease results in exertion-limiting chest pain or poorly-controlled vascular disease results in amputations, a family’s income may be sharply curtailed. (7,8) Furthermore, the intensive and prolonged costs of treatment can be a major financial drain on a family, forcing them to take out loans or sell possessions. (7) A recent World Bank report suggests that this scenario is already widespread, and its prevalence is likely under-estimated owing to a lack of research on the topic. (9)
The economic and human repercussions are further amplified by epidemiological evidence that CVD strikes at much earlier ages in low and middle-income countries than is common in high-income countries. This was best demonstrated by INTERHEART, a case-control study of patients suffering a first heart attack in 52 countries throughout the world. (9) In many large developing regions (notably the Middle East, South Asia, and Africa) the average age of first heart attack is about a decade earlier than is common in developed countries. This gap also appears to be true of other noncommunicable diseases such as diabetes, which itself further increases the risk of an early heart attack. (4,7) Thus, many people suffering a first heart attack and its attendant disability are likely still to be in the prime of their working lives. While thorough research still remains to be conducted, this early-disease paradigm is likely to have a range of pernicious effects on family economic decisions, gender dynamics, and social advancement. (4)
Prevention, Treatment, Attention
Recent studies suggest that developing world CVD and its risk factors can be addressed through a range of cost-effective strategies. Disease prevention is paramount, as INTERHEART demonstrated that 80% of the population attributable risk of heart attack is due to five preventable factors: smoking, obesity, elevated lipids, hypertension, and diabetes. (10) Possible interventions suggested by a recent WHO report include population-level policies such as reducing the salt content of foods, discouraging smoking, designing cities to be more conducive to exercise, and educating people about healthy lifestyle habits. (7) The report further highlights a number of successful schemes and policies, such as exercise promotion in Brazil and tobacco taxation in South Africa. One consequence of the recently signed WHO Framework Convention on Tobacco Control be a reduction in the cardiovascular effects of tobacco use. (11)
Medical treatment of hypertension and secondary prevention of coronary artery disease are also validated, cost-effective strategies that could avert thousands of premature deaths each year. (2) Most of the drugs used to treat and prevent the progression of CVD are already off-patent and cheap, yet all remain under-used. (12) Interestingly, as a result of early successes in campaigns against chronic HIV/AIDS and tuberculosis, it has been recently suggested that community health workers could help prevent and treat hypertension. (13) However, the projected effectiveness of such strategies is limited by the woeful scarcity of research studying the prevention and treatment of CVD in developing countries. (14)
Cardiovascular disease has not garnered the attention of the global health community, despite the fact that it is a leading and growing cause of excess morbidity and mortality in most developing countries. (15) Indeed, many students interested in global health are unaware of its enormous impact, despite the fact that this disease is almost certain to be one of the major international health challenges throughout our careers.
The current paucity of research and policies attests to this lack of awareness. As such awareness is necessary for promoting research, collaboration, advocacy, policy-making, and community-based programs, it is imperative that the global health community pay attention to the complete burden of disease in less developed countries. Only by doing so can we begin to lessen the inequitable hardships faced by those who suffer in silence from this less exotic but no less devastating disease.
Joshua Schulman-Marcus
4th year medical student
Mount Sinai School of Medicine
New York
USA
and
2007-08 Sarnoff Cardiovascular Foundation Fellow
Brigham and Women’s Hospital/Harvard School of Public Health
Boston
USA
jschumar@gmail.com
(1) Mathers C, Lopez A, and Murray CJ. “The Burden of Disease and Mortality by Condition: Data, Methods, and Results for 2001.” Global Burden of Disease and Risk Factors,ed. 45-93. New York: Oxford University Press, 2006
(2) Gaziano TA, Reddy KS, Paccaud F et al. “Cardiovascular Disease.” Disease Control Priorities in Developing Countries (2nd Edition),ed. , 645-662. New York: Oxford University Press, 2006
(3) Lopez AD, Mathers CD, Ezzati M et al. Global and regional burden of risk factors, 2001: systematic analysis of population health data. Lancet 2006; 367:1747-57.
(4) Leeder, S., S. Raymond, H. Greenberg, H. Liu, and K. Esson. A Race against Time: The Challenge of Cardiovascular Disease in Developing Countries. New York: Trustees of Columbia University, 2004.
(5) http://www.who.int/infobase/ (Accessed 11 November 2007).
(6) Joshi R, Cardona M, Iyengar S et al. Chronic diseases now a leading cause of death in rural India - mortality data from the Andhra Pradesh Rural Initiative. Int J Epidemiol 2006; 35:1522-1529
(7) Preventing chronic diseases: a vital investment. Geneva: WHO, 2005
(8) Suhrcke M, Nugent RA, Stuckler D and Rocco L. Chronic Disease: An Economic Perspective. London: Oxford Health Alliance, 2006
(9) Adeyi O, Smith O, Robles S. Public Policy and the Challenge of Chronic Noncommunicable Diseases. Washington DC: World Bank, 2007
(10) Yusuf S, Hawken S, Ounpuu S, et al., INTERHEART Study Investigators. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet 2004;364:937-52
(11) http://www.who.int/tobacco/framework/en/index.html (Accessed 11 November 2007)
(12) Gaziano T, Opie L, Weinstein M. Cardiovascular disease prevention with a multidrug regimen in the developing world: a cost-effectiveness analysis. Lancet 2006; 368:679-86
(13) Abegunde DO, Shengelia B, Luyten A et al. Can non-physician health-care workers assess and manage cardiovascular risk in primary care? Bull World Health Org 2007; 85:432-440.
(14) Mendis S, Yach D, Bengoa R et al. Research gap in cardiovascular disease in developing countries. Lancet 2003; 361:2246-47.
(15) Fuster V and Voute J. MDGs: chronic diseases are not on the agenda. Lancet 2005; 366:1512-14.
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