Editorial
The Rise and Fall of Abdominal Aortic Aneurysm
Frank A. Lederle, MD
I
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So now, with national screening programs gearing up
around the world, we learn from these new studies that the
target condition may be in steep decline. One might well ask
what happened, but the answer, at least in large part, seems
clear. The authors of all 3 studies cite reductions in tobacco
use in their respective countries as the most likely explanation.1–3 Norman et al point to a drop in the adult prevalence
of smoking in Australia from 35% in 1980 to 23% in 2001.
Svensjö et al note that the proportion of 65-year-old Swedish
men who were daily smokers fell from 32% in 1980 to 11%
in 2007.
The strong association between smoking and aortic aneurysm was described by Hammond and Horn in 1958.8 A
systematic review that included this and other large studies
relating smoking behavior to subsequent mortality showed
that the relationship between smoking and aortic aneurysm
was several times stronger than the relationship between
smoking and occlusive vascular disease.9 A large AAA
screening study of US veterans found that smoking accounted
for ⬎70% of all AAAs in that population of mostly older
men,10 a finding that Svensjö et al1 have confirmed in their
similar population. Collin suggested in 1988 that the rise in
AAA deaths in the preceding 35 years in England and Wales
was “a cohort effect associated with the pattern of tobacco
addiction in the 20th century,” particularly affecting those
who came of age “between 1916 and 1948 when cigarette
smoking was common and fashionable.”11 Svensjö et al go on
to speculate that “a further decline in [AAA] prevalence
could be expected over time, as the rate of daily smoking
among men continues to drop in Sweden.”
Are similar trends evident in the United States? The Figure
shows US annual adult per capita cigarette consumption12,13
and age-adjusted AAA mortality per 100 000 white men6,14
by calendar year. Included are abdominal, thoracoabdominal,
and unspecified aortic aneurysm, both ruptured and unruptured (largely elective repair deaths). Besides providing a
compelling illustration of the connection between smoking
and disease, the Figure lends support to the findings from the
other Western countries regarding the declining impact of
AAA. The decline may have seemed less dramatic to practicing physicians than it appears in the age-adjusted, standardized Figure because of the concurrent increases in the US
population and in the proportion of the population that is
older. However, even the raw numbers of AAA-related
deaths in all Americans dropped by 30% from their peak of
11 485 in 1991 to fewer than 8000 in 2007.14 This is still a lot
of deaths, and our efforts to combat the disease should be no
more relaxed than were efforts to control coronary artery
disease following its decline, but it is prudent to consider the
possible effects of this trend.
One obvious expectation is that the number of AAA repair
operations would also decline. Yet Norman et al3 have found
n the current issue of Circulation, Svensjö et al1 report on
an abdominal aortic aneurysm (AAA) screening program
for 65-year-old men in central Sweden. Using the standard
screening test (ultrasound) and AAA definition (an aortic
diameter of 3.0 cm or larger), they found a prevalence of
AAA of 1.7%, which they describe as “the lowest reported in
a predominantly white population to this date,” and postulate
that the explanation “may be an overall decrease of the
disease in the population.” Two other recent studies have
observed markedly decreased mortality from AAA in men in
the past 2 decades in Western countries, with smaller decreases in women. Sandiford et al2 reported that AAA
mortality in men dropped by more than half from 1991 to
2007 in New Zealand, and by a third from 1996 to 2007 in
England and Wales; and Norman et al3 found a 38% decline
in AAA mortality in men from 1999 to 2006 in Australia,
adding that “this suggests a true fall in incidence of AAAs.”
Article see p 1118
These 3 studies may come as a surprise to those who
remember a time not so long ago when AAA was a disease on
the rise. The first alerts back then came from autopsy studies
that charted an increasing occurrence of arteriosclerotic
(many would now question this etiology) aortic aneurysms
beginning in the late 1940s, just as syphilitic aneurysms went
into decline.4 These observations were confirmed in a
population-based study from Rochester, Minnesota, that
found a marked increase in the incidence of AAA between
1951 and 1980 that seemed to reflect more than just improved
case ascertainment.5 This increase was in contrast to the
pattern seen for atherosclerotic occlusive vascular disease,
which declined after 1960. Lilienfeld et al6 calculated ageadjusted rates of aortic aneurysm and AAA mortality from
the US Vital Statistics to demonstrate a severalfold rise from
1951 to 1968 before leveling off at a high plateau. Numerous
ultrasound screening studies subsequently documented a
remarkably high prevalence of AAA in older men, ⬎5% in
some populations.7 These findings prompted randomized
trials of ultrasound screening that demonstrated a large
reduction in AAA-related mortality in older men. Guidelines
and community screening programs followed, and AAA went
from being a somewhat unusual and exotic disorder to one of
the common conditions that primary care physicians address
every day.
The opinions expressed in this article are not necessarily those of the
editors or of the American Heart Association.
From the VA Medical Center, Minneapolis, MN.
Correspondence to Frank A. Lederle, MD, VA Medical Center
(111-O), Minneapolis MN 55417. E-mail [email protected]
(Circulation. 2011;124:1097-1099.)
© 2011 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.111.052365
1097
1098
Circulation
September 6, 2011
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Figure. US annual adult per capita cigarette consumption12,13 and US age-adjusted AAA mortality per 100 000 white men by year. For
1951 to 1978, rates are standardized to the US 1960 population as calculated by Lilienfeld et al,6 and from 1979 onward to the US
1970 population from CDC Wonder.14 Rates include abdominal, thoracoabdominal, and unspecified aortic aneurysm, both ruptured and
unruptured (ICD8: 441.2, 441.9, ICD9: 441.3 to 441.6, ICD10: I71.3 to I71.9), and exclude thoracic aneurysm and dissection. Because
all nonsyphilitic aortic aneurysms and dissection were combined before 1968, and 1967 to 1968 data indicate that thoracic aneurysm
and dissection accounted for 20% of this total, pre-1968 values were reduced by 20% for consistent display. AAA indicates abdominal
aortic aneurysm; ICD, International Classification of Diseases.
only a small decrease in hospital discharges for nonruptured
AAA (again the elective repairs) since 1999 in Australia, and
Svensjö et al1 have found “no signs of a decrease in AAA
repair workload in Sweden.” In the United States, the per
capita incidence of elective AAA repair remained essentially
constant from 1979 to 2002.15,16 Possible explanations for the
discrepancy between disease and treatment include the following: (1) there may be a long delay before the decline
extends to AAAs large enough to require repair, as suggested
by Svensjö et al; (2) the reduction in mortality (though not
prevalence at screening) could at least in part be the result of
successful therapy with elective AAA repair; (3) the workload may be maintained by increased repair of more prevalent
smaller AAAs, for which there is some evidence17; and (4)
the lower perioperative mortality of endovascular repair may
have decreased the number of deaths attributed to AAA
(although randomized trial data suggest that this would not
reflect true long-term gains,18 and again would not affect
screening prevalence). Future studies may determine the
proportional contribution of these and other factors.
Another expected effect of a decline in AAA is on
screening programs, and the authors of all 3 studies considered their findings to have important implications for AAA
screening.1–3 Screening programs that fail to target high-risk
populations are likely to see very low detection rates that
could call the value of the program into question. One large
program whose participants were mostly women and mostly
younger than 65 years reported a detection rate of 0.8%,19 less
than half the rate seen in the Swedish program. If reduced
smoking is causing a reduction in AAA prevalence, as
appears to be the case, then the US Preventive Services Task
Force recommendation20 to limit AAA screening to older
men who have smoked looks prescient. Programs that screen
only men who have smoked may grow smaller but are more
likely to remain effective.
Disclosures
None.
References
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Rise and Fall of AAA
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KEY WORDS: Editorials 䡲 abdominal aortic aneurysms
䡲 incidence 䡲 mortality rates 䡲 smoking
䡲
epidemiology
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The Rise and Fall of Abdominal Aortic Aneurysm
Frank A. Lederle
Circulation. 2011;124:1097-1099
doi: 10.1161/CIRCULATIONAHA.111.052365
Downloaded from http://circ.ahajournals.org/ by guest on June 17, 2017
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