Epidemiology
Historically, the health status and disease profile of a society has been linked to its level of economic and social development.  Industrialization has led to improvements in the treatment of diseases that previously afflicted people, such as infectious diseases and conditions arising from nutritional deficiencies.  Subsequently, noninfectious chronic diseases such as cancer and cardiovascular disease have taken preeminence as the leading causes of death in contemporary society.[5] This phenomenon, termed “the epidemiologic transition,” was described first in 1971 by Abdel Omran, an epidemiologist from Johns Hopkins.[6] The decline in infectious disease mortality and the rise in cardiovascular disease may occur at different times chronologically, but the steps of transition are the same globally.

Omran’s stages of epidemiologic transition can be applied easily to the contemporary international development of cardiovascular disease (see table 2.1).[5]

At any given time, different countries are at varying stages of the epidemiologic transition. Currently, the developing world and middle-income countries are continuing to deal with the burden of infectious and nutritional disease while simultaneously experiencing a rise in cardiovascular disease. With low-cost, highcaloric foods now more readily available in most countries around the world, and with globalization increasing the purchasing power of many individuals, many people are shifting toward a Western diet that is high in saturated fats, trans fats, and processed carbohydrates. Moreover, urbanization transforms the workforce from labor-intensive agricultural work to more sedentary office-based and service-oriented occupations, leading to a decrease in daily physical activity. This shift began in England in the 1920s and later in the 1950s in countries as diverse as Japan and Sri Lanka. Most of the developing world, such as urban China, India, and Latin America are in the third stage, known as the “age of degenerative and manmade disease,” wherein cardiovascular disease accounts for 50 percent of all deaths.[7]

While in Western Hemisphere countries, this transition in the epidemiology of cardiovascular disease occurred over centuries, alarmingly, the developing world is now seeing this shift occurring over the course of decades.[8]

Table 2.1
Modified Model of the Stages of Epidemiologic Transition as It Pertains to Cardiovascular Diseases
Source: Adapted from Yusuf S, Reddy S, Ounpuu S, and Anand S. Global burden of cardiovascular diseases. Circulation. 2001;104:2746-2753.

Whereas many developing countries have made significant improvements in reducing or eliminating infectious diseases, none have totally eradicated their infectious disease burdens.  Thus,  this accelerated change in disease profile adds to existing public health and economic strain, creating a double challenge for countries dealing with infectious and, now, cardiovascular diseases.

The WHO and the World Bank published the Global Burden of Disease study to chronicle the current state of health worldwide. Not surprisingly, the study demonstrated that ischemic heart disease and stroke were the two leading causes of death worldwide with a decline in infant mortality and an improvement in life expectancy in many of the developing countries.  Moreover,  while the birth rate decreased worldwide, life expectancy has increased to such a degree that the average age, worldwide, has become older. With more people living to old age, it is not surprising to see a trend toward diseases of the elderly—that is, degenerative diseases such as cardiovascular disease.[9] Yet, despite the growing prevalence and importance of chronic illness and improvements in treating most infectious diseases, infectious diseases still affiict far too many people in the developing world. Malaria, HIV/AIDS, and tuberculosis remain epidemic, consuming most of the research, resources, and public health focus in those areas. Now, as the world recognizes the new epidemics of obesity, hypertension, dyslipidemia, diabetes, and cardiovascular disease, additional resources and a communal commitment are needed to decrease the growth of these “modern” conditions.