Aspirin & bleeding

No drug is without undesirable side effects and aspirin is no exception. With aspirin, the main risk is bleeding.
Bleeds from the stomach occur throughout the general population, and each year about one person in every thousand experiences a stomach bleed. Daily, low-dose aspirin increases this by about 70% – that is, to around two or perhaps three persons each year in every thousand taking aspirin. Bleeding is more frequent in older people, but over time the risk of a bleed diminishes. [See references 1-3 below]

A more serious worry is bleeding into the brain, leading to a haemorrhagic stroke. Within the community generally, about three people in every ten thousand (10,000) experience such a bleed each year. Low-dose daily aspirin increases this rate by about 40% to about four persons per year in every 10,000 taking aspirin, per year. [See references 1-3 below]

A bleed from the stomach is a crisis! Nevertheless, the evidence from a number of studies of aspirin gives considerable reassurance about the seriousness of the bleeds caused by aspirin. [See reference 4 below]First: The risk of a stomach bleed reduces over time, and after about three years of aspirin taking the evidence from trials is that the risk of a bleed attributable to aspirin, appears to be minimal. [See references 5 and 6 below]

Second: The likelihood of a stomach bleed is increased greatly if the stomach is diseased, that is, if there is already a stomach ulcer, or an infection of the stomach. [See reference 2 below] Before taking aspirin, people with stomach trouble or a history of this, and those with frequent indigestion should seek advice about whether or not they should take aspirin at all, or whether they should take a stomach protecting drug along with the aspirin. These protecting drugs reduce the risk of a bleed by about one half. [See references 7-9 below]

Third: The stomach bleeds cause by aspirin appear not to be the most serious. Severe bleeding can rarely lead to death, but there is no valid evidence that low-dose aspirin increases the risk of a fatal bleed. Relevant evidence comes from careful overviews of multiple randomised trials, involving tens of thousands of subjects. [See reference 4 and 10-13 below]

Fourth: The frequency and the seriousness of the stomach bleeds caused by aspirin is far less than the frequency and seriousness of the conditions prevented by aspirin, namely heart attacks and cancers. [See reference 4, 14 and 15 below]

All the above was about stomach bleeds. Bleeding into the brain, causing a haemorrhagic stroke is far less common, but much more serious, being a disabling and life-threatening event.Each year about three people in every 10,000 experience a haemorrhagic stroke, and low-dose daily aspirin increases this rate to about 4 persons in every 10,000 per year. [See references 2 and 3 below]

Raised blood pressure is a major factor in brain haemorrhage and the risk of a stoke is more than doubled for every 20mmHg rise in blood pressure. [See reference 10 below] Blood pressure should therefore always be checked and appropriately treated if raised, before aspirin taking commences.

A large trial of aspirin gives some reassurance about aspirin and haemorrhagic stroke. The trial was conducted in almost 20,000 patients all of whom had raised blood pressure and all of whom were receiving ‘optimal’ treatment for their hypertension. There was no excess in the number of haemorrhage strokes – 19 patients on aspirin experienced a stroke, while 20 who received no aspirin had a stroke. [See reference 16 below]

If a bleed occurs in a patient taking aspirin, the natural response is to stop taking the aspirin. The decision to stop should however be taken cautiously. Suddenly stopping risks a rebound in vascular risk, and an increase in the risk of death. If it is decided to stop the drug it should be withdrawn slowly. [See references 17 and 18 below]

Finally: It is most important that the balance between the benefits of a drug and the risks are not evaluated simply in terms of the numbers of people who benefit and the number who are harmed. Yet this is how aspirin is often evaluated.

Remember – the benefits of aspirin are a reduction in the development of disabling and life threatening diseases (cancer, heart disease and stroke), while the risks of low-dose aspirin are a stomach bleed, for which there is no valid evidence of death, and only very rarely a haemorrhagic stroke, which may be fatal. [See reference 14 and 15 below].

Take whatever advice you wish, but do make sure that in the end it is your decision whether or not to take aspirin. The protection of your health, and the prevention of disease, is ultimately your own responsibility!

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