Friday, June 11, 2010

Is Long Term Aspirin Therapy Safe?

Tags: Aspirin, Safe?, Long-term, Benefits, Improved, Warfarin, Program

Is Long Term Aspirin Therapy Safe? One of the first detailed study has been carried out about the benefits of aspirin verses the disadvantage of excess bleeding in preventing further strokes and heart attacks. It seems to help in the initial months of therapy, but the years people taking aspirin, it does not seem to make a difference. So we must consider whether this recent study indicates to me that when the extend of advertising by Bayer on the benefits of aspirin to prevent strokes and hearth attacks was due to this contrary study.

John GF Cleland

Authors and Disclosures

Posted: 04/15/2010; Future Cardiology. 2010;6(2):141-146. © 2010 Future Medicine Ltd.

  1. Abstract and Introduction
  2. Aspirin Fallacies: Is there a Sound Biological Rationale for Aspirin?
  3. Is Long-term Aspirin Therapy Effective?
  4. Is Aspirin Safe?
  5. Is the Correct Dose of Aspirin Known?
  6. Is Aspirin an Appropriate Background Therapy for Other Anti-thrombotic Agents?
  7. Has the Introduction of New Treatments Altered the Efficacy of Aspirin?
  8. Inexpensive?
  9. Is Aspirin Free from Commercial Interest?
  10. References

Abstract and Introduction

Introduction A recent meta-analysis concluded that considerable uncertainty exists regarding the wisdom of giving aspirin for the prevention of a first vascular event in populations who are at a low or intermediate cardiovascular risk.[1] This meta-analysis did not include three recent primary prevention trials[2–4] – these were resoundingly neutral or showed evidence of harm. A substantial segment of the medical community was surprised at this, with their reactions ranging from disbelief to anger. However, they would not have been surprised had they carefully read the original reports used by the meta-analysis and considered other relevant studies, such as the Pulmonary Embolism Prevention trial[5] (n = 13,356), which showed a 33% increase (hazard ratio: 1.33 [95% CI: 1.00–1.78]; p = 0.05) in the risk of fatal or nonfatal myocardial infarction in patients who were assigned to receive aspirin rather than placebo after a hip fracture (an elderly group of patients who had a high prevalence of occult coronary disease).

The Antiplatelet Trialists[1] recently stated that:

"Low-dose aspirin is of definite and substantial net benefit for many people who already have occlusive vascular disease."

However, this organization has strongly promoted aspirin use and stifled any contrary opinion.[6] The data entered into this meta-analysis are different from those reported in the trials themselves.[6] Changing the data after a study is complete is incorrect and may cause bias.

Many doctors have been deceived by biased reporting in the literature, which is a blight on the editorial reputation of many of the most eminent medical journals.[7,8] It is not clear whether editors were duped by cleverly written manuscripts or were seduced by preconceived notions regarding the efficacy of aspirin. However, the aspirin story is now unraveling.[9] Guideline groups on both sides of the Atlantic no longer recommend aspirin use in patients with heart failure, even if they have coronary disease.[10,11] It is likely that further trials will be conducted to either refute or confirm the safety and efficacy of long-term aspirin use in other clinical settings. Those promoting aspirin as part of a 'polypill' approach to cardiovascular risk should be alert to these issues and, if they are genuinely concerned about patients' well-being, clinical science should be at the forefront of designing appropriate randomized placebo-controlled trials in order to demonstrate the safety and efficacy of the aspirin component.[12] …


Why are We so Bad in Primary Care at Initiating Warfarin in Atrial Fibrillation Patients? This article is an enlightened approach to reducing strokes in patients with atrial fibrillation (AF). It discusses some freely available software called 'The Auricle' and shows how this can easily be used to calculate the annual risk of a stroke. GPs and patients are supported in the careful decision about anticoagulation. To this end the programme has an e-consultation option to ask the opinion of a local cardiologist with the flexibility to attach an electrocardiogram (ECG), echo or clinic letter, if desired. All the details and the cardiologist's opinion can be electronically filed in the patient's notes to confirm that the pros and cons of warfarin were fully debated.


If GPs can be adequately advised and supported in prescribing warfarin to appropriate atrial fibrillation (AF) patients, then we have the potential to save at least 12,500 strokes per year according to the Department of Health. The National Institute for Health and Clinical Excellence (NICE) estimated that 355,000 patients were at high risk of stroke in AF in the UK and that 166,000 of them were not on warfarin (47%). An audit undertaken in Leeds used Read coding queries to apply a CHADS2 score ( table 1 ) to AF patients in participating practices and to identify what thromboprophylaxis was used.

The results concorded closely to the NICE estimate. It was found that out of 2,116 patients reviewed with AF, 50% were at high risk of stroke with AF and 46% of those were not on warfarin. Most of these patients were on aspirin. A switch to warfarin therapy for these patients, where possible, would prevent many strokes each year.

The aim is to make a Guidance on Risk Assessment and Stroke Prevention for Atrial Fibrillation (GRASPAF) audit tool widely available across England to aid GPs in finding patients at risk of stroke and not currently taking warfarin. It has been available via local cardiac and stroke networks from the Heart Improvement Programme website ( since June 2009 (contact: Keith Tyndall, Arrhythmia Nurse on

There are many cogent reasons why GPs are reluctant to initiate warfarin. While ignorance among GPs and patients is an obvious possibility, there is disproportionate concern about the prescription and consumption of warfarin. This has to be balanced against an annual stroke risk that can approach 20% in high-risk individuals. Of course prescribing warfarin can indeed rarely be fatal. Every year patients die of bleeds that are iatrogenic but this has an inordinate influence on GPs. It needs to be remembered that the Birmingham Atrial Fibrillation Treatment of the Aged (BAFT A) study showed no significant difference between aspirin and warfarin in both intra-cerebral and extra-cerebral bleeds in elderly patients.

Nevertheless, it is as if Hippocrates is whispering in our ears his law of therapeutics that states: "First do no harm". We know that the risk of stroke in AF can be reduced by 70% with warfarin and only 20% with aspirin. It is, therefore, surprising how many patients are nonetheless treated with aspirin, potentially leading to thousands of preventable strokes. It is clear that, when prescribing in AF, GPs are between a rock and a hard place. The Quality Outcomes Framework (QOF) incentive scheme does not currently discriminate between warfarin and aspirin in AF, which may lead GPs to think that aspirin is good enough. There are also other significant pressures against warfarin, which include some softer contraindications like risk of falls and, therefore, bleeds.

Professor Greg Lip, Clinical Adviser for the NICE guidelines, quotes the work of Man-Son-Hing et al.[1] to calculate that you need 295 falls in a patient to justify not prescribing warfarin! Confusion is another reason offered, if it is felt that accurate compliance with warfarin is at risk.

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