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Affluence and the Worldwide Distribution of Cardiovascular Disease Risks

Affluence and the Worldwide Distribution of Cardiovascular Disease Risks


Cardiovascular diseases (CVDs) are responsible for more than 16 million deaths worldwide, about 30% of total global deaths. Many of these deaths could be prevented by tackling major risk factors such as overweight and obesity as a result of unhealthy diet and physical inactivity, and smoking. Traditionally, CVDs have been considered a “Western” disease or a “disease of affluence” and not a pressing public health concern for low-income populations. However, within upper-middle-income and high-income countries, CVDs and their associated risk factors are increasingly concentrated among the lowest socioeconomic groups, and globally, 80% of all CVD deaths are in low-income and middle-income countries.

In this month's PLoS Medicine, Majid Ezzati and colleagues conclude that a large proportion of the world's population living in low-income and middle-income countries should indeed be the focus of attention for CVD risk factors. This attention is needed because the aging populations of the currently low-income and middle-income countries are expected to be those among whom major cardiovascular risk factors will increasingly be concentrated.

The patterns of risks in relation to one another and to economic variables such as income are not fully established at the population level but need to be understood if better long-term policies and interventions are to be deployed. Ezzati and colleagues examined when interventions should be started by looking at the relationship between nutritional cardiovascular risk factors—overweight and obesity, and elevated blood pressure and cholesterol—and three economic indicators, using data for more than 100 countries. Their analysis uncovered economic–epidemiological patterns more complex than the “Western” or “affluence” labels would suggest. They found that body mass index (BMI) and cholesterol increased rapidly in relation to national income, then flattened, and eventually declined. BMI increased most rapidly until an income of about I$5,000 (international dollars) and peaked at about I$12,500 for women and I$17,000 for men. Cholesterol showed a similar pattern, but with some delay. The authors also found an inverse relationship between BMI/cholesterol and the share of household expenditure put towards food, and a positive relationship with proportion of population in urban centers, which may be due to changes in patterns of diet and physical activity with city life. For blood pressure and cholesterol, possible contributors to the decline at higher levels of income include dietary changes and use of pharmacological interventions.

As more interventions for blood pressure and cholesterol are adopted in high-income societies, the three risk factors will become a feature of low-income and middle-income nations, the authors say. Demographic and technological changes are increasingly modifying the income patterns of cardiovascular risk factors and shifting their burden to the developing world; as a result, low-income and middle-income countries will simultaneously face the burden of infectious disease and cardiovascular risk factors. Unless better interventions are pursued, we will face a world in which all major diseases are the diseases of the poor, the authors warn. (See also the Perspective by Thomas Novotny [DOI: 10.1371/journal.pmed.0020104].)