Screening for abdominal aortic
aneurysms (AAAs) with cheap ultrasound exams could slash
the death rate in half, according to a new study in
the May 15 Annals of Internal Medicine.
AAAs have always been a huge issue,
but as baby boomers hit old age the incidence is set
to explode. Deadly if they rupture, they have virtually
no symptoms so most patients don't even know they've
got them until it's too late.
Experts have wondered for years
if screening is the answer, but the sheer volume of
cases — over 5% of people will have an AAA by the
time they hit 65, and the incidence keeps growing as
they age — made it seem unfeasible. But the Annals
study adds to a growing body of literature supporting
widespread ultrasound AAA screening in dramatically
reducing deaths — and costs.
MASS-IVE
REDUCTION
The Annals study is a seven-year followup to the large
UK Multicentre Aneurysm Screening Study (MASS) which
found good evidence to support AAA screening. The study
estimated benefits and cost-effectiveness of ultrasound
screening for AAA in a population-based sample of 67,770
men aged 65-74.
MASS screened roughly half the
men recruited for the study, the other half served as
controls. The screened participants who were found to
have AAA were either brought in for follow-up screening
or offered surgery, depending on the size of the aneurysm
(anything bigger than 5.5cm is usually repaired). After
seven years, about 301 AAA-related deaths had occurred,
196 in the control group, 105 in the screened group
— an astonishing 50% reduction in mortality.
LET'S
SCREEN
This finding makes Dr Thomas Forbes very happy. The
vascular surgery chief at the London Health Sciences
Centre thinks it's high time Canada had a nationwide
screening program for AAA.
"At our practice, we're doing over
300 surgical interventions for AAA per year," he says.
"Ten to 20% of them are for ruptures right now, and
I think that we could reduce that portion by half, if
not more, through better screening efforts. As healthcare
professionals, screening is an opportunity to save more
lives, and we should be excited by this."
Dr Forbes has been involved in
the Health Technology Utilization Guidelines of Ontario
(HealthTUGO), a collaborative effort to promote health
information and technology. Earlier this year the group
released AAA screening guidelines that recommend screening
for all men and women age 65 and up who've ever smoked
or have other risk factors such as positive family history
for AAA, or show symptoms of peripheral artery diseases
like atherosclerosis. The Canadian Cardiovascular Society
has released similar guidelines. Despite this, not enough
Canadian physicians are screening for AAA, says Dr Forbes.
PRE-EMPTIVE
STRIKE
Dr Forbes suggests that a screening-dependent, planned
approach means surgery is done electively before the
aneurysm ruptures. This reduces mortality risks from
roughly 75% (ruptured) to just 5%, and even less with
new endovascular techniques. "Occasionally it will be
spotted when a patient gets an x-ray for something else,
or is lucky enough to be of a physical stature which
permits detection by digital inspection." Emergency
repairs have a survival rate considerably lower than
that of elective AAA surgeries.
The MASS study estimates cost savings
for screening would be $19,500 US per life-year gained,
although the authors caution this figure could vary
country-to-country. "Ultrasound is cheap, uncomplicated
and relatively comfortable, making it less of a turn-off
for patients," notes Dr Forbes.
TOP
10 KILLER
"AAAs are among the top 10 causes of death in North
America," explains Dr Forbes, "and ultrasound screening
is a highly suitable approach to improving AAA outcomes.
AAA has few physical symptoms prior to the pain after
a rupture, and at that point, only about half of people
make it to the hospital alive, and half of those who
make it to hospital won't come through emergency surgery."
Dr Forbes says some people might
find HealthTUGO's guidelines over the top because they
suggest the same screening for women even though AAA
is much less common in them. He says they did this to
keep things straightforward. "Primary care physicians
are inundated with screening recommendations. These
things have to be very comprehensive, so we made the
message as simple as possible."
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