Cardiovascular disease remains the leading cause of mortality among middle-aged adults globally, accounting for 40 percent of all deaths. But in high-income countries (HIC) cancer is now responsible for twice as many deaths as cardiovascular disease, according to findings from the Prospective Urban and Rural Epidemiologic (PURE) study. Another report from PURE found that modifiable risk factors contributed to the majority of cardiovascular disease and related deaths globally. Both reports were presented Sept. 3 at ESC Congress 2019 and simultaneously published in The Lancet.

The PURE study is the only large prospective international cohort study with substantial data from a large number of low-income countries (LIC), middle-income countries (MIC) and HIC, using standardized and concurrent methods of sampling, measurement and follow-up.

For the first report, researchers followed 162,534 middle-aged adults (aged 35-70 years, 58 percent women) in five LIC, 12 MIC and four HIC over a median of 9.5 years (between 2005-2016).

Cardiovascular death was 2.5-times more common in middle-aged adults in LIC compared with HIC, although LIC experience a substantially lower burden of risk factors for cardiovascular disease compared with wealthier countries. Other findings include a substantially lower rate of first hospitalization and of medications for cardiovascular disease in LIC and MIC, compared with HIC, and the researchers suggest this may contribute to the higher rate of cardiovascular mortality in LIC.

"The world is witnessing a new epidemiologic transition among the different categories of noncommunicable diseases (NCDs), with cardiovascular disease no longer the leading cause of death in HIC," said lead author Gilles R. Dagenais, MD. "Our report found cancer to be the second most common cause of death globally in 2017, accounting for 26 percent of all deaths. But as cardiovascular disease rates continue to fall, cancer could likely become the leading cause of death worldwide, within just a few decades."

While the study found the incidence of cardiovascular disease per 1,000-person years is 7.1, 6.8 and 4.3 in LIC, MIC and HIC respectively, it conversely found cancer, pneumonia, chronic obstructive pulmonary disease and injuries is least common in LIC and most common in HIC. Overall mortality rates were twice as high in LICs vs. MIC, and four times higher in LICs vs. HIC, though rates of deaths from cancer were similar across all country income levels.

"While long-term cardiovascular disease prevention and management strategies have proved successful in reducing the burden in HIC, a change in tack is required to alleviate the disproportionately high impact of cardiovascular disease in LIC and MIC," said principal investigator Salim Yusuf, DPhil, FACC. "Governments in these countries need to start by investing a greater portion of their gross domestic product in preventing and managing noncommunicable diseases including cardiovascular disease, rather than focusing largely on infectious diseases."

The second report, presented by Yusuf, found that 70 percent of cardiovascular disease cases and deaths globally are due to modifiable risk factors. The study examined the relative contribution (population attributable factor [PAF]) of 14 modifiable risk factors among 155,722 community-dwelling, middle-aged people without a history of cardiovascular disease in the same countries as the first report.

Metabolic risk factors were the largest contributing risk factor for cardiovascular disease globally (41.2 percent), with hypertension (22.3 percent) the leading metabolic risk factor.

However, the relative importance of cardiovascular disease risk factors varied widely between the categories of countries. For deaths, the largest group of PAFs overall were for behavioral risk factors (26.3 percent), but in LIC and MIC, the importance of household air pollution, poor diet, low education and low grip strength were substantially larger compared with their impact in HIC. Metabolic risk factors, including high cholesterol, abdominal obesity or diabetes, played a larger role in causing cardiovascular disease in HIC, compared with LIC.

"We have reached a turning point in the development of cardiovascular disease prevention and management strategies," said Annika Rosengren, MD, a study author.

"Efforts to tackle cardiovascular disease through focusing on a small number of behavioural risk factors, such as reducing smoking, are important, but these efforts should expand to better blood pressure control and better use of secondary prevention, with simple and effective low-cost medications," said co-lead author Philip Joseph, MD.

In terms of generalizing results to all countries, the authors note the lack of data from west Africa, north Africa or Australia; the modest number of participants from the Middle East; and data from LICs are predominantly from south Asia with a few African countries.

"However, the inclusion of nearly 900 urban and rural communities from multiple countries in different regions of the world provides substantial diversity of risk factors and contextual variables and makes it likely that the PURE results are more broadly applicable than most previous studies," said study author Antonio Dans, MD.

Countries included in the PURE Study are Argentina, Bangladesh, Brazil, Canada, Chile, China, Colombia, India, Iran, Malaysia, Pakistan, Palestine, Philippines, Poland, Saudi Arabia, South Africa, Sweden, Tanzania, Turkey, United Arab Emirates and Zimbabwe.

Clinical Topics: Cardiovascular Care Team

Keywords: ESC 19, ESC Congress, Cardiovascular Diseases, Neoplasms, ACC International

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