MEDIA STATEMENT
18th
September 2009
Aspirin for primary prevention of cardiovascular
disease in people with diabetes
An article in Pulse (September 11th) has suggested that the use
of aspirin for primary prevention in people with diabetes has
begun to be phased out. The basis for this claim is:
1. A draft guideline from the Scottish InterCollegiates
Network (SIGN)(1) does not recommend aspirin as primary prevention
of vascular disease in people with diabetes
What do treatment guidelines say?
Evidence-based treatment guidelines in the UK, Europe and the
United States currently recommend low-dose aspirin to reduce the
risk of cardiovascular events (such as heart attack) in people
with diabetes who do not currently have clinically apparent cardiovascular
disease but who are at increased risk of developing it.
Examples of these guidelines include those published by the National
Institute for Health and Clinical Excellence (NICE) , the International
Diabetes Federation, the American Heart Association and the American
Diabetes Association.2-5
NHS patients in England and Wales
The guideline of most importance to the NHS in England and Wales
is the NICE guideline, published in 2008.(2) It identifies two
groups of people with diabetes who should be offered low-dose
aspirin (75 mg/day):
• a person who is 50 years old or over if their blood pressure
is below 145/90 mmHg
• a person who is under 50 years old and has significant
other cardiovascular risk factors (features of the metabolic syndrome,
strong early family history of cardiovascular disease, smoking,
hypertension, extant cardiovascular disease, microalbuminuria)
NHS patients in Scotland
Guidance for NHS Scotland is published by SIGN. It is now consulting
on a new guideline on the management of diabetes.(1) The current
draft, which is not in force, states: Low-dose aspirin is not
recommended for primary prevention of vascular disease in patients
with diabetes. SIGN makes this statement because, it says, Recent
trials [refs 6 - 8] have increased the uncertainty about the role
of aspirin in primary prevention. Consultation on this draft ends
in October.
2. The Aspirin for Asymptomatic Atherosclerosis Trial
(AAAT),(9) presented at the European Society of Cardiology’s
annual congress in Barcelona but not yet published in full, suggested
that the risk of primary prevention with aspirin outweighed the
benefit in people at high vascular risk
Care should be taken when interpreting the findings of AAAT. There
were methodological shortcomings: an accompanying commentary on
the trial noted: lack of power (amplified by relatively poor compliance)
does seem to provide a reasonable explanation for the AAA null
findings.
Additionally, the study population appeared to be a low-risk group.
International guidelines do not recommend aspirin therapy for
individuals at low CVD risk.(10-13)
3. A recent meta-analysis (14) questioned the use of aspirin
for primary prevention
This meta-analysis included 95 000 patients with low average risk
of vascular events, some of whom had diabetes. It stated: Although
the evidence from the six primary prevention trials reviewed here
is consistent with some net benefit in such patients [with diabetes],
the evidence from three other primary prevention trials in diabetes
has been unpromising. The analysis continued by noting that doubts
about the role of aspirin are being specifically addressed by
two much larger trials now underway. One of these (ASCEND) is
a 10,000-patient clinical trial to examine the effects of low-dose
aspirin in the diabetic population. Supported in part by Bayer,
this study is of significant size and will add to the current
body of evidence on which professional recommendations are based.
A more recent meta-analysis,(15) conducted specifically to address
the conflicting evidence, concluded: While there are insufficient
data among patients with diabetes to conclusively show a benefit
of aspirin for primary prevention of cardiovascular events our
data suggest, but do not confirm, that the relative benefit of
aspirin is similar in patients with and without diabetes.
4. A quote from Professor David Fitzmaurice, who stated:
“The use of aspirin in primary prevention has always been
an article of faith rather than evidence based…”
The clinical guidelines currently in force were based on a large
body of evidence from randomised trials. In addition, the role
of aspirin as primary prevention has been supported independently
by two other meta-analyses.(16,17) The more recent meta-analyses
reflect the conflicting data from the latest clinical trials.
What is the position of the Aspirin Foundation?
Disagreements in the evidence about the role of aspirin as primary
prevention in patients with diabetes are being addressed by ongoing
clinical trials. Until then, the balance of evidence favours the
use of aspirin and this is reflected in current clinical guidelines.
The decision whether to take low-dose aspirin must be made jointly
by the clinician and the patient. Patients who are already taking
aspirin prescribed by their doctor should always consult their
doctor before modifying or stopping their treatment.
Ends
References
1. Scottish InterCollegiates Network. Management of diabetes.
A draft for consultation. September 2009 (www.sign.ac.uk/pdf/Diabetes-consultation-draft.pdf)
2. National Collaborating Centre for Chronic Conditions. Type
2 diabetes: national clinical
guideline for management in primary and secondary care (update).
London: Royal College of
Physicians, 2008 (www.rcplondon.ac.uk/pubs/contents/7db731d7-2731-4b14-aaf1-2bab37370d6b.pdf)
3. International Diabetes Federation. "Global Guideline for
Type 2 Diabetes." 2005; p.45-55. (www.idf.org/webdata/docs/IDF%20GGT2D.pdf)
4. American Diabetes Association. Aspirin therapy in diabetes.
Diabetes Care 2004;27(suppl 1):S72-S73
5. Buse JB et al. Primary prevention of cardiovascular diseases
in people with diabetes mellitus: a scientific statement from
the American Heart Association and the American Diabetes Association.
Circulation 2007;115:114-26
6. Belch J et al. The prevention of progression of arterial disease
and diabetes (POPADAD) trial: factorial randomised placebo controlled
trial of aspirin and antioxidants in patients with diabetes and
asymptomatic peripheral arterial disease. BMJ 2008;337:a1840 doi:
10.1136/bmj.a1840
7. Ogawa H et al. Low-dose aspirin for primary prevention of atherosclerotic
events in patients with type 2 diabetes: a randomized controlled
trial. JAMA 2008;300:2134-41
8. Hansson L et al. Effects of intensive blood-pressure lowering
and low-dose aspirin in patients with hypertension: principal
results of the Hypertension Optimal Treatment (HOT) randomised
trial. HOT Study Group. Lancet 1998;351:1755-62
9. Fowkes G. AAA: Randomised controlled trial of low dose aspirin
in the prevention of cardiovascular events and death in subjects
with asymptomatic atherosclerosis. August 2009 (www.escardio.org/congresses/esc-2009/congress-reports/Pages/706001-706002-fowkes-patrono.aspx)
10. Pearson TA et al. AHA Guidelines for Primary Prevention of
Cardiovascular Disease and Stroke: 2002 Update. Circulation 2002;
106:388-91
11. Mosca L et al. Evidence-Based Guidelines for Cardiovascular
Disease Prevention in Women: 2007 Update. Circulation published
online Feb. 19, 2007; DOI: 10.1161/CIRCULATIONAHA.107.181546,
and, J Am Coll Cardiol 2007; 49:1230-50
12. Graham I et al. European guidelines on cardiovascular disease
prevention in clinical practice: full text. European J Cardiovasc
Prev Rehab 2007; 14 (suppl 2): S1-S113
13. US Preventive Services Task Force. Aspirin for the Prevention
of Cardiovascular Disease: U.S. Preventive Services Task Force
Recommendation Statement. Ann Intern Med. 2009;150:396-404
14. Antithrombotic Trialists’ (ATT) Collaboration. Aspirin
in the primary and secondary prevention of vascular disease: collaborative
meta-analysis of individual participant data from randomised clinical
trials. The Lancet 2009;373:1849-60
15. Calvin AD, Aggarwal NR, Murad MH et al. Aspirin for the primary
prevention of cardiovascular events: a systematic review and meta-analysis
comparing patients with and without diabetes. Diab Care 2009;
published online September 9th
16. Eidelman RS, et al. An update on aspirin in primary prevention
of cardiovascular disease. Arch Int Med 2003;163:2006-10
17. Bartolucci A, Howard G. Meta-analysis of data from the six
primary prevention trials of cardiovascular events using aspirin.
Am J Cardiol 2006;98:746-50
