"A success story," says PURE investigator
PARIS -- The leading cause of death in high-income countries has commenced its shift from cardiovascular disease (CVD) to cancer, an analysis of 21 countries across five continents indicated.
In the PURE study, CVD remained the most common cause of mortality overall, but accounted for just 23% of deaths in the included high-income nations, reported Salim Yusuf, MD, PhD, of Health Research Institute at McMaster University in Hamilton, Ontario, at the European Society of Cardiology (ESC) congress here.
This compared with 41% and 43% in the middle- and low-income countries, respectively. Cancer, meanwhile, was responsible for 55% of deaths in the richer nations versus 30% and 15% in middle- and low-income countries.
"We're seeing a new transition, the old transition was infectious diseases giving way to non-communicable disease, now we see a transition within non-communicable disease," Yusuf said during a press briefing. "In rich countries, cardiovascular disease is going down."
He emphasized that for now the findings applied specifically to the high-income nations that took part in the study -- Canada, Sweden, the United Arab Emirates, and Saudi Arabia. Among these, the ratio of CVD to cancer deaths was 0.40. Further, four more upper-middle-income nations -- Argentina, Chile, Poland, and Turkey -- also had similar ratios.
"This is a success story," said Yusuf, who told MedPage Today that PURE is a harbinger of things to come over the coming decades.
"It won't happen overnight, and it won't happen universally," he said. "It's like a sentinel flag, not every one will show it."
Salim Yusuf, MD, PhD, presenting results of PURE at an ESC press briefing
The CVD to cancer deaths ratios were 1.3 in middle-income nations and 3.0 in low-income countries, according to the findings, results of which were published simultaneously in The Lancet.
But aren't cancer death rates going down as well?
"The answer is yes," said Otis Brawley, MD, former chief medical officer at the American Cancer Society, now of Johns Hopkins University in Baltimore. "It's just heart disease death rates are going down even faster."
Brawley pointed to recent research showing that certain states and women in the U.S. have undergone this same transition, and now too show higher death rates from cancer.
High-income countries are better able to handle prevention of CVD than cancer, said Brawley, who was not involved in the research, noting the difference in lag time for their respective prevention strategies.
"If I treat enough newly diagnosed hypertensives today, I am likely to prevent some strokes in 5 years. If I stopped some smokers from smoking today, I'm preventing lung cancer 20 and 25 years from now," said Brawley. "The other issue that I hear about a lot is we need to treat, treat, treat, because prevention takes 10, 15, 20 years to actually show benefit, and I wish we could do both in this country."
A second analysis of PURE found that globally, roughly 70% of deaths from CVD could be attributed to modifiable risk factors, with hypertension accounting for about 22.3% of the attributable risk. This was followed by elevated lipids (8.1%) and household pollution (6.9%) -- "This was a big surprise to us," said Yusuf.
In high-income nations, high cholesterol (20.7%) led the way, followed by tobacco use (15.7%), hypertension (14.6%), and diabetes (7.8%).
"I want to hasten to add that the difference in risk between high-, middle-, and low-income countries for cardiovascular disease is not due to risk factors," Yusuf said. "Risk factors if anything are lower in the poor countries compared to the high-income countries."
Rather, he said, the differences in CVD mortality were largely due to differences in healthcare.
"The findings from the PURE study that indicate a large proportion of cardiovascular disease events and mortality can be attributed to a small number of modifiable risk factors are consistent with and extend the findings from several other large studies," wrote Stephanie Read, PhD, of the Women's College Research Institute, Women's College Hospital in Toronto, and Sarah Wild, PhD, of the Usher Institute and University of Edinburgh, in an editorial
that accompanied The Lancet
"Reducing the prevalence of hypertension at the community level and improving treatment of hypertension require a variety of approaches," they said. "Priorities will differ by country and will depend on factors such as expected benefit, access to health care, and quality of health care."
ESC had a global theme this year, and other studies at the meeting -- HOPE 4 and a full-sodium salt swap-out study, among them -- took unique paths to reduce CVD risk in low- and middle-income countries.
Additionally, said Read and Wild, improving education in these nations might yield larger returns in reducing CVD mortality than efforts targeting some of the other modifiable factors noted in the study -- diabetes, abdominal obesity, physical activity, or depression. In middle-income countries for example, low education (6.3%) came in second as far as modifiable risk factors for CVD, behind only hypertension.
For the PURE analysis, the researchers assessed deaths and risk factors among over 150,000 participants ages 35 to 70 who were enrolled from 2005 to 2016, and who were then followed for a median 9.5 years. Roughly 11% of the cohort were from the four high-income countries, about 66% were from 12 middle-income nations, and 23% were from five low-income countries. Deaths occurred in 7% of the cohort, and overall mortality rates were lowest in the richer nations, at 3.4 deaths per 1,000 person-years compared with 6.9 and 13.3 per 1,000 in the middle- and low-income countries, respectively.
Some PURE authors reported relationships with the Heart and Stroke Foundation of Canada, grants from the Canadian Institutes of Health Research, and the Ontario Ministry of Health and Long-Term Care.
Read and Wild declared no conflicts of interest.
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Read the original article on Medpage Today: 'Sentinel' Nations See Heart Deaths Slip Below Cancer