Screening for abdominal aortic aneurysm
BMJ 2009; 338 doi: https://doi.org/10.1136/bmj.b2185 (Published 24 June 2009) Cite this as: BMJ 2009;338:b2185All rapid responses
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The evidence base supporting screening for abdominal aortic aneurysm
(AAA) is not as solid as Professor Buxton asserts.(1)
The U.S. Preventive Services Task Force (USPSTF) does not endorse
such screening. Their rationale is that there is good evidence that
screening and early treatment leads to important harms, including an
increased number of surgeries with associated clinically-significant
morbidity and mortality, and short-term psychological harms.
The USPSTF concludes that the balance between the benefits and harms
of screening for AAA is too close to make a general recommendation for
screening.(2)
The men invited for screening should be given this information as
well as the likelihood that they will benefit — about one in a thousand.
Consent for screening is only valid if it is well informed.
(1) Buxton MJ, Screening for abdominal aortic aneurysm. BMJ 2009;
338: b2185.
(2) U.S. Preventive Services Task Force. Screening for Abdominal
Aortic Aneurysm: Recommendation Statement. AHRQ Publication No. 05-0569-A,
February 2005. Agency for Healthcare Research and Quality, Rockville, MD.
http://www.ahrq.gov/clinic/uspstf05/aaascr/aaars.htm
*
Competing interests:
None declared
Competing interests: No competing interests
It was timely that your issue, BMJ, June 27th 2009, juxtaposed Dr
Iona Heath’s observations about the personal impact of breast screening
with rarefied and inconclusive health economic analyses of aortic
aneurysm (AAA) screening. Dr Heath quotes Sackett’s descriptions of
preventive medicine as ‘aggressively assertive pursuing symptomless
individuals and telling them what they must do to remain healthy… and
presumptuous, confident that the interventions it espouses will, on
average do more good than harm to those who accept and adhere to them’.
But if this is indeed the case with well established breast screening,
how much more so for the new AAA screening programme.
There is an ethical imperative to screening which is much more
demanding than that for the treatment of ill patients who present to their
doctor for help. Screening is offered to people who believe themselves to
be well. The doctor’s duty to first do no harm is all the greater in this
case. Emergency aneurysm surgery carries a grave prognosis but even with
elective aneurysm surgery, there is an operative mortality, between 1%-
and 8% depending which audit series is being reported. To inflict on
otherwise innocent patients the choice to have major surgery which may
kill them tests the bounds of doing no harm too far. It is also grossly
unfair on the surgeons who are a part of this decision and I know several
who are uneasy about this programme. AAA screening places an onus on
patients to be part of a risk assessment and decision that they have not
been asking to make- to live with the knowledge of their aneurysm and have
it on their heads if it ruptures, or accept a major surgical procedure
that may kill them.
On a population basis, well men will die because of their agreement to
surgery. Net benefit to some, if there is any, over loss to others does
not adequately justify AAA screening. AAA screening does not meet the
basic ethical imperative for a screening programme.
The question of cost effectiveness becomes a secondary consideration.
But cost effectiveness is not the same as affordability. Given the
impending need to cut the NHS budgets in accordance with the dire
national financial position, it would be foolish to embark on a new
unaffordable, high risk programme of contested cost effectiveness, which
may benefit some but will cost others their lives.
Competing interests:
None declared
Competing interests: No competing interests
Endovascular repair has now taken over as the majority treatment in most major
vascular centres (90% in ours). It is probably not much more expensive as
although the device costs more the reduced hospital stay and reduction of need
for intensive care balance this out.
Once screening is established it would be political dynamite to cancel it even if
cost ineffectiveness is later proven - cf breast screening
Competing interests:
None declared
Competing interests: No competing interests
To screen or not to screen?
We agree with Martin Buxton that the present evidence favours
screening for AAA in the United Kingdom. We also agree that the results
from MASS pertain to the UK population and the important caveat of the
introduction of EVAR needs addressing in light of cost effectiveness.
However, the Danish study by Ehlers et al uses a probabilistic model
to attempt to address the same issue in Denmark. Their findings conflict
with the MASS study. One study is a randomised control trial producing
robust evidence for screening in a specific cohort and the other is a
computational study, albeit using existing data, in a different cohort.
Comparing the 2 studies is akin to a comparison between apples and
oranges.
Until a RCT is performed in the Danish cohort, we suggest that the
best evidence for the benefits of screening in the UK population rest with
data from the MASS trial with the intervention of choice being open
surgery.
References:
1. Multicentre aneurysm screening study (MASS): cost effectiveness
analysis of screening for abdominal aortic aneurysms based on four year
results from randomised controlled trial.
Multicentre |Aneurysm Screening Group. BMJ 2002 Nov 16;325(7373):1135.
2. Screening men for abdominal aortic aneurysm: 10 year mortality and
cost effectiveness results from the randomised Multicentre Aneurysm
Screening Study.
Thompson SG; Ashton HA; Gao L; Scott RA; Multicentre |Aneurysm Screening
Group.
BMJ 2009 Jun 24;338:b2307.
3. Analysis of cost effectiveness of screening Danish men aged 65 for
abdominal aortic aneurysm.
Ehlers L, Overvad K, Sørensen J, Christensen S, Bech M, Kjølby M.
BMJ. 2009 Jun 24;338:b2243.
Competing interests:
None declared
Competing interests: No competing interests