PURE: Telling CVD Risk-Factor, Outcomes Paradox in Affluent vs Poorer Nations

September 02, 2013

AMSTERDAM — The burden of cardiovascular disease risk factors is more pronounced in affluent countries than in the poorest nations, yet wealthier countries also have the lowest CVD mortality and the poor ones the highest, suggests an early analysis from a major, ongoing epidemiologic study with insights about how to confront the epidemic of CVD around the world, researchers say [1].

Dr Salim Yusuf

In the Prospective Urban Rural Epidemiologic (PURE) study encompassing 155 000 adults in >600 communities in 17 countries around the world, surveyed from 2003 to 2010, mortality from MI, stroke, or heart failure was seven times higher in low-income countries compared with high-income countries. The mortality was of intermediate magnitude in middle-income countries, observed Dr Salim Yusuf (McMaster University, Hamilton, ON) when presenting PURE here at the European Society of Cardiology (ESC) 2013 Congress.

But surprisingly, he said, high-income countries showed markedly higher INTERHEART risk scores derived from CVD risk factors like smoking, poor diet, low activity levels, family CV history, high BP, and diabetes, averaging about 13, compared with lower-income countries with average scores of about 8 (middle-income countries scored at about 10.5).

On the Wealth of Nations

The apparent disconnect between CVD risk-factor burden and CVD outcomes by country affluence, Yusuf said, "indicates that something else besides risk factors" is playing a role, something that "reflects marked differences in the quality of care between countries." He and his colleagues have concluded that superior healthcare and management of CVD in wealthier countries attenuates the impact of greater risk-factor burden.

There's internal consistency in the data, Yusuf observed. "Compared with lower-income countries, in higher-income countries there is more non-major CVD, suggesting earlier detection and better management of less severe CVD."

The findings mean that "the higher incidence of major CVD and fatal CVD in poorer countries is not due to a higher level of risk factors," suggesting that measures to improve CVD outcomes designed for Europe and North America, for example, won't necessarily work in developing nations.

"We need to think about improving case management, early detection, primary prevention, and secondary prevention--these are essential if we want to control the epidemic [of CVD in] middle-income and low-income countries," Yusuf said. "So just as we talk about policies to reduce risk-factor burden, we need to work with governments to improve healthcare systems [to make them] stronger and efficient.

Incidence of CVD Per 1000 Person-Years in PURE by Country Income Level, 3.9 Years Follow-up

End point High Middle Low p
Any fatal CVD 1 4.86 7.25 <0.0001
Major CVD (MI, stroke, HF) 1 1.20 1.43 <0.0001
Any other hospitalized CVD 1 0.47 0.26 <0.0001
Total CVD 1 0.86 0.88 <0.05

In the current analysis, Yusuf said, high-income countries included Canada, Sweden, and the United Arab Emirates; among the middle-income countries were Argentina, Brazil, Chile, Poland, Turkey, South Africa, Colombia, China, and Iran; and low-income countries included India, Pakistan, Bangladesh, and Zimbabwe.

Dr John Gordon Harold

Commenting on the PURE analysis for heartwire , Dr John Gordon Harold (Cedars-Sinai Heart Institute, UCLA) agreed that CVD-prevention solutions in the high-income countries aren't necessarily appropriate for lower- and middle-income countries. It's not enough, for example, to tell people in low-income countries that taking statins and controlling blood pressure are the answer. "For the average worker in low-income countries, even inexpensive statins would be perhaps three or four days of income." It should challenge policy makers to look at health recommendations and strategies by the specific needs and capabilities of each country, he said.

As the assigned discussant for Yusuf's presentation, Dr Joep Perk (Linnaeus University, Kalmar, Sweden) said the findings shouldn't be all that surprising. "It shows that in the Western world, the high-income countries, we do detect disease earlier; we have better methods to deal with it and better methods to follow-up."

"It's Become Your Disease"

Perk agreed that "taking our guidelines and our system down to these countries is simply impossible." The PURE study "will stress [that] politicians in these countries . . . improve legislation--for example, on tobacco smoke." It should help providers fight for stronger resources for their countries. "But most of all, it will also show the people of the Third World that cardiovascular disease is not any more a disease from Sweden or Canada, it's become your disease, you have to find your own solution. And in this way, I feel the PURE study has opened doors that will not simply close anymore."

Added Harold: "I think the PURE study has thrown down the gauntlet to health policy makers, particularly in the World Health Organization and the UN. [CVD] is an epidemic that's going to explode, and we have to be prepared to deal with it. It's going to require resources, it's going to require vision, and it's going to require cooperation."

PURE is funded by government sources in participating countries and by many companies, Yusuf said. The biggest contributors in industry are Boehringer Ingelheim, Servier, Astra Zeneca, Sanofi, and GlaxoSmithKline. Yusuf, Perk, and Harold had no disclosures.

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