The causes of heart disease are surprisingly the same in every region and race, and stress seems to play a more important role in heart attacks than previously recognized, a major new study has found.
Nearly all of what is known about the causes of heart disease comes from studies of white people in rich countries, because that's where the illness first emerged.
However, with the globe's No. 1 killer now taking over the developing world as well, scientists have been worried that the way it is tackled in the West - by combatting smoking, obesity, blood pressure and cholesterol, among other things - may not necessarily apply in poorer countries.
"Some 80 percent of the heart disease in the world is in developing countries, yet 99 percent of the research done into the causes of heart disease comes from developed countries and largely white, European populations, so we really don't know for sure whether we can apply the results of the studies we've got to the rest of the world," said the study's leader, Dr. Salim Yousef, a professor of medicine at McMaster University in Canada, explaining what prompted the study.
The research, presented Sunday at the annual meeting of the European Society of Cardiology, followed 29,000 people in 52 countries. It took a decade and 262 scientists to complete the work, which, according to the editor of The Lancet medical journal, is probably the most robust study on heart disease risk factors ever conducted.
The scientists, who concluded that about 90 percent of the risk factors for heart attacks can be prevented, are scheduled to published the findings in The Lancet next week.
"This study confirms that the risk factors are the same all over the planet and ... has made it possible to assess the weight of the different risk factors," said Dr. Jean-Pierre Bassand, president of the European Society of Cardiology. "It's a fantastic study.
"It is clear that not a single continent, not a single civilization, not a single race, can be spared from cardiovascular disease, which will hit humankind more dangerously than the Black Death in the Middle Ages," said Bassand, who was not connected with the study or the publication. "What we need is political action."
The study examined 15,000 people who had suffered their first heart attacks and matched them with someone of the same age, sex and location who had not had a heart attack.
A bad cholesterol profile, measured using a new test considered better than the standard one that looks at the balance between good HDL cholesterol and bad LDL cholesterol, was the most important risk factor.
Smoking was the next most important player, followed by diabetes, high blood pressure and a fat belly.
Stress came next, followed by inadequate fruit and vegetable intake, then lack of exercise. Light to moderate alcohol consumption was found to be of slight benefit.
Yousef said he was surprised by some of the findings.
"My expectation when I went into this was that I would find ethnic and regional variations, because some of our earlier papers had suggested that. It just shows you need massive numbers to get the right answer," Yousef said. "I thought smoking would be bad everywhere, but the (cholesterol) I wasn't sure."
But what was most unexpected, he said, was the power of stress.
"The standard biomedical scientist is really not interested in stress, partly because they are uncomfortable with the concept, the certain softness with which you measure it," Yousef said. "I came into this with a little educated hostility regarding stress, but I've changed my mind after seeing the data."
The problem is psychological, not physical, stress - things such as tension at home or at work, financial problems, divorce, losing a child, or feeling of loss of control.
Most experts believe that about half of the risk of a heart attack can be prevented. The latest study, however, indicated that about 90 percent of the causes of heart attacks can be averted.
The study indicated that about 50 percent of the chance of having a heart attack comes from a bad cholesterol profile alone, Yousef said.
"Globally, in urban populations, there's practically nobody with a level of (cholesterol) that avoids an increased risk of heart disease," he said.
Smoking is responsible for another 36 percent of the risk, the study found.
"The impact of these risk factors was the same in every ethnic group and in every region of the world," Yousef added. "That means preventive messages can be simple and we can use the same strategy, of course adjusted for economic and cultural circumstances, in every part of the world."
The difference between men and women seen in the West was also observed all over the world. Men usually get heart attacks at about 57, women at 65.
Although that sex difference held true everywhere, the study found that in southern Asia, the Middle East and Africa, people suffer heart attacks about 10 years earlier.
The study implies that the main way to tackle the problem is societal change, including better urban planning and health-promoting food policies and advertising regulations, experts said.
The study comes on the heels of a World Health Organization vote in May to implement a global strategy on diet and exercise aimed at combatting obesity, diabetes, heart disease and other illness linked to an unhealthy lifestyle.