Combating the Epidemic of Heart Disease
Authors: Daniel Levy
Journal: JAMA (2012)

AT THE BEGINNING OF THE 20TH CENTURY, THE 3 leading causes of death in the United States were infectious diseases—pneumonia, tuberculosis, and diarrhea—which in combination claimed 539 lives per 100 000. Lurking in the background as the fourth leading cause of death was heart disease (137 deaths per 100 000). But this would change. With life expectancy of only 47 years at the beginning of the century, people did not live long enough for heart disease to claim many lives. Without a means for accurate diagnosis, many deaths from heart disease went unrecognized. With the advent of the electrocardiogram to facilitate the diagnosis of heart disease, antibiotics to treat infectious diseases, and increasing life expectancy, the number and proportion of deaths due to heart disease soared. During the Great Depression, the number of deaths due to heart disease was twice that of the next leading cause of death (pneumonia). In 1945, at the time of President Roosevelt’s fatal brain hemorrhage due to decades of uncontrolled hypertension, heart disease accounted for more deaths in the United States than the next 3 causes combined. Deaths due to heart disease peaked in 1968 at 374 per 100 000. Necropsy studies of soldiers killed in the wars in Korea and Vietnam provided an opportunity to define the prevalence of subclinical coronary atherosclerosis in young people. In 1953 Enos et al described coronary lesions discovered at autopsy in 300 male soldiers (mean age, 22 years) killed in the Korean War. Gross evidence of coronary disease was present in 77% of the decedents: 35% with fibrous thickening, 26% with a coronary artery narrowed by 10% to 49%, and 15% with a coronary occlusion of 50% or more. In 1971, McNamara et al reported evidence of coronary atherosclerosis in 45% of 105 Vietnam War combat deaths (mean age, 22 years), with 5% having severe coronary disease. In their concise descriptive narratives, these studies provided unequivocal evidence of the silent burden of coronary atherosclerosis in young, otherwise healthy adults, and in finding a “reservoir” of carriers of disease, they helped explain the emergence of heart disease as a 20th century epidemic among middle-aged and older adults. In this issue of JAMA, Webber and colleagues report on the prevalence of coronary and aortic atherosclerosis in 3832 US service members who died from combat or unintentional injuries from 2001 to 2011 while serving in support of military operations in Iraq or Afghanistan. With a mean age of 27 years, the service members’ prevalence of coronary atherosclerosis of any degree was 8.5%, a value considerably lower than reported by Enos et al (77%) and McNamara et al (45%). Minimal, moderate, and severe coronary atherosclerosis were present in only 1.5%, 4.7%, and 2.3% of the recent decedents, respectively. The large sample size of the study provided robust estimates of the low burden of subclinical atherosclerotic disease and permitted an exploration of differences in prevalence of disease across various demographic strata. The prevalence of atherosclerosis increased with age and was greater in those with lower education levels but was not associated with occupation, ethnicity, service branch, or military rank. Taken together, the reports by Enos et al, McNamara et al, and Webber et al offer cross-sectional perspectives on subclinical atherosclerosis in healthy young military service members, but unlike standardized, population-based, cross-sectional studies (eg, the National Health and Nutrition Examination Survey [NHANES], for example), these studies are not directly comparable and also might not be generalizable to the US population of young adults. Unlike NHANES, the 3 autopsy studies were conducted at irregular intervals and were restricted to military personnel who were likely to be healthier than the US population as a whole. The restrictive criteria used by Webber et al to establish the presence of cardiovascular disease risk factors, along with the “healthy warrior effect,” may have resulted in low measures of prevalence of key risk factors. Specifically, the prevalence of obesity (4%), smoking (3%), hypertension (1%), dyslipidemia (0.7%), and impaired fasting glucose (0.2%) were markedly lower than among comparable age groups in the US population or compared with published estimates of risk factor prevalence in the military. The methods used for ascertainment of several risk factors likely underrepresented their true prevalence and limited the authors’ ability to draw conclusions about risk factor associations with