A new study shows that the rate of American service members with signs of coronary artery disease has declined sharply in the last half century, falling to roughly 1 in 10 military personnel today from about 8 in 10 during the Korean War.
The findings came as a surprise to some researchers, who expected that the nationwide rise in obesity and Type 2 diabetes, including among young people, might have led to a similar trend in heart disease in the military. But instead it appears that national reductions in other risk factors for heart disease, like hypertension, smoking and high cholesterol, have had a greater effect on cardiovascular health.
Some experts had debated whether the steep decline was real, given that those in today?s all-volunteer military are fitter than the general population and, presumably, those who served during the draft era of the Korean War. But most said the trend was hard to dispute.
?The changes in prevalence of coronary disease are so great that I can only conclude that most of the differences are likely real,? said Dr. Daniel Levy, a cardiologist and director of the National Heart, Lung and Blood Institute?s Framingham Heart Study, who was not directly involved in the study. ?This isn?t a subtle difference; it?s a vast difference.?
The authors of the new study, which was published in The Journal of the American Medical Association on Tuesday, drew their findings from autopsies and medical records of nearly 4,000 service members killed in Iraq and Afghanistan from 2001 to 2011. Most of them were men, with an average age of 26. Over all, 8.5 percent had some degree of hardening and narrowing of the coronary arteries, known as coronary atherosclerosis.
During the Korean War, pathologists who carried out similar research, groundbreaking at the time, on 300 soldiers killed in combat found that 77 percent had coronary atherosclerosis. The finding that so many seemingly healthy men in their late teens and 20s had significant buildup of plaques in the arteries shattered the perception of heart disease as purely an affliction of older people, revealing that the disease had a silent and relatively early onset.
Two decades later, a study of 105 soldiers killed in Vietnam showed that nearly half had signs of coronary atherosclerosis as well.
A shift in the 1970s from a military draft to voluntary enlistment may have produced a so-called healthy warrior phenomenon in recent years, said Dr. Bryant J. Webber of the Uniformed Services University of the Health Sciences in Bethesda, Md, who led the current study. Only 4 percent of those who died in Iraq or Afghanistan were obese, for example, compared with about 18 percent of 18- to 29-year-olds in the general American population.
During the Korean War, ?some of the people they classified as having early or mild disease we might classify as normal? today, Dr. Webber added.
Even so, the downward trend in evidence of heart disease held up even when the researchers looked solely at advanced cases of atherosclerosis, which are hard to misinterpret. Fifteen percent of the Korean War soldiers had severe coronary atherosclerosis, compared with 5 percent of the Vietnam soldiers and just 2.3 percent of the troops in the latest study.
?That?s a fairly reliable and accurate measure, and that decline is pretty steep,? Dr. Webber said.
While obesity and diabetes dominate the public health discussion today, other cardiovascular risk factors, like high cholesterol and uncontrolled high blood pressure, have been falling for decades. And between 1980 and 2000, smoking rates among service members fell by 40 percent. Nationwide, deaths from heart disease, after adjusting for age, have dropped by 72 percent since 1968.
Dr. Levy said it was easy to connect the dots: The prevalence of coronary artery disease in young people is on the decline. The Korean War study revealed a silent epidemic of coronary artery disease, he said, and now the pendulum is swinging in the other direction as a result of prevention efforts.
?There?s a lot of good news here,? he said. But for the general population, at least, ?the problem of obesity holds the potential to reverse these gains.?
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