December 25th, 2012
Autopsy Studies Find Dramatic Drop in Early Atherosclerosis Over the Past 60 Years
Larry Husten, PHD
Military service members who died during the past decade were far less likely to have atherosclerosis than service members who died in Korea or Vietnam, according to a new study published in JAMA. Although it is impossible to fully understand the causes and implications of the finding, the results provide powerful new evidence of a very long-term, enormous reduction in the prevalence of coronary disease, especially in younger people, although an aging population and disturbing trends in obesity and diabetes mean that cardiovascular disease will continue to be a major public health problem for the foreseeable future.
Bryant Webber and colleagues analyzed autopsy reports and available health data from 3832 service members who died of combat or unintentional injuries in Afghanistan and Iraq and compared their findings with those from similar studies conducted during the Korean and Vietnam wars. 8.5% of the newer group had evidence of coronary atherosclerosis, compared with 77% in the Korean War group and 45% in the Vietnam War group. The authors acknowledge many reasons why the groups should not be directly compared but conclude that the overall trend in the reduced prevalence of atherosclerosis is undoubtedly true.
As might be expected, service members with atherosclerosis were older and more likely to have dyslipidemia, hypertension, or obesity than service members without atherosclerosis. Surprisingly, cigarette smoking was not significantly associated with atherosclerosis in this study.
In an accompanying editorial, the Framingham Study’s Daniel Levy writes that “the main finding of this study is valid: the prevalence of atherosclerosis in young men today is much lower than the prevalence in the Korean or Vietnam War eras. If these findings are generalizable to the US population as a whole, then the cardiovascular health of the US population may have improved appreciably over the past 6 decades.”
Levy writes that the concurrent decline in mortality from cardiovascular disease is likely the result of advances in both prevention and treatment, but only advances in primary prevention can explain the trend found in the autopsy studies. Nevertheless, he notes, cardiovascular disease is still the leading cause of death in the U.S.: “The national battle against heart disease is not over; increasing rates of obesity and diabetes signal a need to engage earlier and with greater intensity in a campaign of preemption and prevention.”
5 Responses to “Autopsy Studies Find Dramatic Drop in Early Atherosclerosis Over the Past 60 Years”
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Statistic illusions?
The data used in the article cited (JAMA. 2012;308(24):2577-2583) may have multiple readings:
a) “As might be expected, service members with atherosclerosis were older and more Likely to have dyslipidemia, hypertension, or obesity than service members without atherosclerosis”, the Author’s (and Larry’s) conclusions,
other:
b) The classic factors that are considered to cause atherosclerosis explain only 92 of the 389 cases of atherosclerosis;
c) Only 14 of the 389 cases of atherosclerosis correspond to dyslipidaemia;
d) etc. etc.
If we are waiting for a particular outcome we also tend to be less demanding in the analysis. To what extent our prejudices can lead to biased analysis?
Since we know that moderate alcohol consumption correlates with less ASCVD, does anyone know if alcohol consumption has become more common with individuals in the past 60 years, or smoke fewer cigarettes, or both?
I do not think that we can conclude that early atherosclerosis has declined since 1950s from this study because these are two distinct populations.The comparison involves a general population (conscripted Korean War soldiers) with all the co-morbidities that that carries to a select population (volunteer Iraq War Soldiers) that are appropriately healthy and appropriately motivated to enter into the Army.
Secondly, the definition of “atherosclerosis” and “fatty streaks” is considerably different between the two populations. In the authors comments they acknowledge that in “the Korean study grouped fibrous thickening with fatty streaking as atherosclerosis, but it is now understood that intimal thickening may occur physiologically as a nonatherosclerotic adaptation.” This would account for a considerable difference.
I generally agree with Dr. Ryan’s comments. It is interesting though to compare the generalized decline in cardiovascular event rates over time, especially with regard to STEMI (Yeh RW, Sidney S, Chandra M, Sorel M, Selby JV, Go AS.Population trends in the incidence and outcomes of acute myocardial infarction. N Engl J Med 2010;362:2155– 65) and the findings of the current study. It seems that the “classic MI” of yesteryear is a relatively less frequent event nowadays than the minor NSTEMI which we see in spades. Perhaps a major shift in lifestyle, especially smoking, over the decades has shifted the trends in cardiovascular medicine from younger men who smoke having “the big one” to chronic ischemic heart disease among the elderly in the setting of other prolonged chronic disease states such as CKD.
I agree with Dr Ryan. I believe the pathologists’ interpretation of what constitutes atherosclerosis has changed. I also believe we are comparing a group of war casualties with a vastly different idea of what a healthy lifestyle is. For example, Korea era and Vietnam era troops got cigarettes in their rations, while Iraq troops did not. The authors of the study did acknowledge there are significant differences between the two groups.
Be that as it may, I still feel there is value in the study in that it does supply some supporting evidence explaining the decrease in atherosclerotic vascular disease and the general decline in cardiovascular morbidity and mortality in the US over the last 60 years.