PRB

Developing countries are undergoing a rapid epidemiological transition—from infectious diseases such as diarrhea and pneumonia to chronic ones such as heart disease—that threatens to overwhelm their strapped health systems and cripple their fragile economies.

Of the top four causes of death worldwide, three—cardiovascular disease (CVD), cancer, and chronic respiratory diseases—are associated with chronic disease.¹ Almost three times as many people die annually from CVD (which includes heart disease and stroke) as from AIDS, tuberculosis, and malaria combined.² And CVD, chronic respiratory diseases, cancer, and diabetes made up 60 percent of the 58 million annual worldwide deaths estimated for 2005—with more than three-quarters of these deaths occurring in developing countries.³

In October 2005, the World Health Organization (WHO) released a report—Preventing Chronic Disease: A Vital Investment—to raise awareness about this largely invisible epidemic in developing countries and to issue a call to action for national governments, international organizations, civil society, and the private sector.⁴ WHO proposes a new global goal: to reduce the projected trend of chronic-disease death rates by 2 percent each year until 2015. Such a reduction would prevent 36 million people from dying of chronic disease in the next 10 years, most of them in middle- and low-income countries.

Prevention of chronic disease is key to meeting this goal. Yet without urgent attention to the scope of the problem, developing-country governments will not be able to bolster health system resources nor shift the focus of their health services adequately. Although some effective prevention programs have shown success in developed countries (particularly in tobacco control and education), caution must guide application to other settings.

Lifestyle Choices Are Major Risks

A number of factors—including population aging and a decline in the number of deaths from infectious diseases—have led to a growing burden of chronic disease in less developed countries. (See A Critical Window for Policymaking on Population Aging in Developing Countries for an overview of the trends and consequences of population aging.) Urbanization (because of increased migration to cities); industrialization (as more in-country manufacturing leads to decreased work in agriculture); and globalization (through more interdependent worldwide trade relationships, especially regarding food supplies) have contributed to this transition.

But three of the most important risk factors for chronic disease—unhealthy diet, physical inactivity, and tobacco use—are related to lifestyle choices. The prevalence of these risk factors is increasing globally as diets shift to foods high in fats and sugars, while work and living situations become more sedentary. Increased marketing and sales of tobacco products in low- and middle-income countries have also meant greater exposure to the risk of tobacco in developing countries.

Obesity contributes to a number of chronic diseases: hypertension, heart disease and stroke, osteoarthritis, high cholesterol, and sleep apnea and respiratory problems. It is also the most influential risk factor for adult-onset (or Type 2) diabetes, which affects an estimated 177 million people globally—two-thirds of whom live in the developing world.⁵ (See Obesity-related Diseases Creep Up On Developing Countries for more details on these trends.)

Unfortunately, obesity rates are climbing in developing countries: More than 1 billion people worldwide are overweight, as well as more than 30 percent of the populations in Latin America, the Caribbean, the Middle East, and northern Africa.⁶ Of the 22 million children under age 5 globally who are overweight, 77 percent live in developing countries.⁷ Populations living on Pacific and Indian Ocean islands now have the highest obesity prevalence in the world—with some, such as urban Samoa, as high as 75 percent.⁸ And in China, the proportion of calories from fat in the average individual diet has doubled over a 20-year period, with levels now resembling a high-fat American diet.⁹

Likewise, smoking is a risk factor for a number of chronic diseases, including CVD, cancer, and chronic respiratory conditions. The pattern of global deaths from smoking is shifting dramatically, with about as many people now dying annually (about 2 million) from smoking in the developing world as in industrialized nations.¹⁰ Currently, 1.3 billion people worldwide smoke, 84 percent of them in developing and transitional economy countries.¹¹ China alone has 350 million smokers, and 57 percent of all Chinese men smoke.¹²

“In most regions, current trends in cigarette smoking, obesity, physical activity, and diet will predictably lead to further increases in the health and economic burden of chronic disease for decades into the future,” says Walter Willett, professor of epidemiology and nutrition at the Harvard School of Public Health.

Understanding the Health Burden of Chronic Disease

While diarrhea and pneumonia once were the leading causes of mortality in developing countries, the toll of those and other infectious diseases has largely been surpassed by deaths from chronic disease:

• CVD is the number one cause of death worldwide, accounting for 30 percent of all deaths globally in 2005. CVD accounts for three-quarters of the mortality from chronic diseases in developing countries.¹³ These deaths are especially prevalent in urban centers of countries such as China and India, where CVD is now the leading cause of death (see table).¹⁴
• Cancer accounts for nearly 7 million annual deaths worldwide, and one-half of these fatalities are in developing countries—10 percent of all deaths in these countries.¹⁵
• Chronic respiratory diseases, chief among them chronic obstructive pulmonary disorder (COPD), accounts for an estimated 2.75 million deaths worldwide annually—almost 5 percent of all deaths.¹⁶

Cardiovascular Disease: Total DALYs (in millions)

Sources: Christopher J.L. Murray and Alan D. Lopez, “Policy Forum,” Science 274, no. 5288 (1996); WHO, The World Health Report 2004 (www.who.int); and Colin Mathers and Dejan Loncar, “Updated Projections of Global Mortality and Burden of Disease, 2002-2030: Data Sources, Methods and Results” (2005) (www.who.int/evidence/bod).

Surprisingly, nearly one-half of chronic disease deaths worldwide occur among people who are under 70 years old, and one-quarter among those who are under age 60. Moreover, chronic disease deaths occur at much earlier ages in low- and middle-income countries than in high-income countries.

Indeed, CVD is also increasingly affecting developing country populations in their productive years. In one seven-country study, CVD death rates were significantly higher among the working-age populations (ages 35 to 64) in low- and middle-income countries than in the United States and Portugal.¹⁷ About 41 percent of all CVD deaths in South Africa and 35 percent in India occur during the working years.¹⁸ CVD also now accounts for as many deaths in young and middle-aged adults as HIV/AIDS.

Finally, beyond their contributions to mortality, chronic diseases contribute significantly to the burden of disease disability borne in developing countries. The most popular measure of the burden of any disease is the DALY, or disability adjusted life year—a summary measure that includes the number of healthy years of life lost to premature death and the number of years spent with less than full health.¹⁹

Measured in DALYs, chronic disease is responsible for 86 percent of the burden of ill health for those under age 70 worldwide. And because men die at earlier ages from chronic disease than women, they bear a greater share of the burden of chronic disease.

Health Systems Ill-Prepared to Make the Shift

Whether health systems in developing countries can ramp up to deal with the consequences of a wave of chronic diseases remains in question. Analysts such as Derek Yach, professor of global health at the Yale School of Public Health, say such a transition calls for nothing less than a systemwide reorientation. “This transformation will require addressing incentives, human resources, information technology, and public needs together in new ways,” says Yach.

Although proven interventions exist to address many of the problems of chronic disease, the health systems in many developing countries must contend with the practical realities of limited resources, especially given the extra burden of infectious diseases. In South Africa, for example, the demand on health services is particularly high: Managing chronic diseases (which are responsible for 41 percent of the country’s deaths) adds to the already heavy onus of addressing infectious diseases, including the 20 percent of people there ages 15 to 49 who are infected with HIV.²⁰

Developing-country health systems also often cannot provide good opportunities for diagnosing and treating the rising tide of chronic diseases. Moreover, the disabilities resulting from chronic disease demand longer-term care and services than these health systems are structured to provide.

Lessons from developed countries demonstrate that prevention can go a long way toward addressing the risk factors for many chronic diseases. The WHO Global Strategy on Diet, Physical Activity and Health and the WHO Framework Convention on Tobacco describe prevention measures.²¹ For instance, the tobacco treaty requires countries to:

• Impose restrictions on tobacco advertising, sponsorship, and promotion;
• Establish new packaging and labelling of tobacco products;
• Establish clean indoor air controls; and
• Strengthen legislation to clamp down on tobacco smuggling.
• In addition, investment in health systems must be made to expand the skills and training for health care providers, and to purchase equipment and supplies and to upgrade technology. Overall management of health systems also needs to pay attention to management of chronic diseases. As Yach puts it: “Low-middle income countries face the same major challenge to their health systems. How best to shift from an historically developed health care system—designed to address acute infectious diseases and maternal deaths—to one that can address chronic diseases?”

These issues—a pervasiveness of risk factors, a high burden of chronic diseases with an early age of onset, and lack of preparedness of health systems—raise some important questions about the implications of chronic diseases for developing countries as well as the urgent need for national prevention strategies. To address some of these questions, PRB is publishing, as of January 2006, a series of Web-exclusive articles on aging and health care, featuring the demographic problem of aging and its consequences, the preparedness of health care systems, and aging and health care in China. Click on Aging for a list of articles.