Contemporary Prevalence of Atherosclerosis in Military Personnel at Autopsy
Abstract & Commentary
By Andrew J. Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco.
Source: Webber BJ, et al. Prevalence of and risk factors for autopsy-determined atherosclerosis among U.S. service members, 2001-2011. JAMA 2012;308:2577-2583.
Autopsy studies from the Korea and Vietnam wars, which demonstrated that atherosclerosis begins in teens and young adults, have revolutionized our understanding of the pathogenesis and progression of coronary artery disease (CAD). Mortality from ischemic heart disease has declined in the United States since then. To determine the prevalence of CAD in young adults in the modern era, Webber and colleagues present data from the autopsies of persons serving the U.S. military from 2001-2010. They linked data from the autopsy reports of all U.S. service members who died of combat or unintentional injuries with the demographic and medical encounter data from the Defense Medical Surveillance System. Hearts were visually inspected for the presence of CAD in the major epicardial coronary arteries, and this was classified according to the following scheme: minimal (fatty streaking only), moderate (10-49% luminal narrowing of ≥ 1 vessel), and severe (≥ 50% narrowing of ≥ 1 vessel). The presence of aortic atherosclerosis was also noted. To assess the contribution of risk factors to age-adjusted prevalence of atherosclerosis, the authors present the data as age-adjusted prevalence ratios (PR).
A total of 3832 autopsy results were included, with the subjects ranging in age from 18-59 years (mean, 25.9 years), with 98.3% males. The prevalence of any CAD was 8.5%; severe CAD was present in 2.3%, moderate in 4.7%, and minimal in 1.5%. The prevalence of aortic atherosclerosis was 5.7%. The prevalence of any atherosclerosis (i.e., either coronary or aortic atherosclerosis or both) was 12.1%. Those with atherosclerosis were older (mean age 30.5 ± 8.1 years vs 25.3 ± 5.6 years; P < 0.001). Those ≥ 40 years had about seven times the prevalence of disease as compared with those ≤ 24 years (45.9% vs 6.6%). Atherosclerosis prevalence was higher in those with risk factors. The prevalence of any atherosclerosis in those with no risk factors was 11.1%, whereas in those with dyslipidemia it was 50.0% (PR, 2.09), in those with hypertension 43.6% (PR, 1.88), and in those with obesity 22.3% (PR, 1.47). Smoking was not associated with a higher prevalence of atherosclerosis. The authors conclude that among deployed U.S. service members who died of combat or unintentional injuries and received autopsies, the prevalence of atherosclerosis varied by age and cardiovascular risk factors.
This study demonstrates a much lower rate of CAD (8.5%) in military autopsies than was shown in the Korean (77%) and Vietnam (45%) wars. This suggests a significant reduction in the prevalence of atherosclerosis in young U.S. service personnel. This may be due to a true decline in the prevalence of atherosclerotic disease, or it may also be influenced by methodological differences between the different studies. The earlier reports were from the era of conscription, when smoking rates were higher, and the rate of autopsy was approximately 1%. The current study is from this century, from a time of voluntary enlistment, and has a > 60% autopsy rate. There are likely significant biases and methodological differences between studies, but the current study is encouraging that the prevalence of CAD is declining. It is enticing to speculate that lower smoking rates or better education about lifestyle choices have beneficially impacted our communities. Alternatively, we may just be seeing the natural history of the rise and fall of prevalence as seen in any epidemic. Regardless, CAD remains a leading cause of morbidity and mortality in the United States. Any decline in the prevalence of atherosclerosis is most welcome news.