By Ross Walker

One of the most common questions I am asked, especially in people over the age of 50 is, ‘Should I be taking aspirin every day as a preventative?’ Although aspirin has been available for many years and has a very strong evidence base, as with all pharmaceuticals, there are some concerns around its widespread use.

Many studies over the years have shown around a 25% reduction in cardiovascular disease, including heart attack and stroke. Over the past decade, there have been a number of studies suggesting a reduction in the risk and recurrence of many common cancers.

Recent studies have suggested around a 20% reduction in breast cancer and breast cancer metastasising. In some studies, there have been suggestions of up to a 50% reduction in colon cancer. One study has suggested a reduction in chronic liver disease with the regular use of aspirin. It is not known whether this is specific for aspirin, or whether this pertains to all antiplatelet agents such as the commonly used clopidogrel.

So, with all of this very positive information in support of the regular use of low-dose aspirin as a preventative, should not all of us over the age of 50 be taking this? Well, unfortunately, it is not that simple. I would estimate that around 10% of the population are prone to easy bruising and bleeding and this certainly becomes more prominent as we age. Many of my patients on chronic aspirin, or clopidogrel therapy, have the tell-tale subcutaneous blotches of this treatment. Mind you, I do have a number of patients who are not on this therapy and still have these subcutaneous blotches caused by fragile capillaries beneath the skin, as we age.

Probably somewhere between 5-10% of people who take any form of aspirin, including the enteric-coated low-dose aspirin, may still suffer reflux and other forms of heartburn as a consequence of this therapy. This is not the case with clopidogrel. Aspirin is also associated with chronic inflammation in the stomach, and people who take regular aspirin do have higher rates of gastrointestinal bleeding, intracranial bleeding and, of course, increased bleeding if there is any trauma involved.

A recent study from the Oxford vascular group followed just under 3200 patients for around 10 years. These patients all had some vascular event, such as a transient ischaemic attack, ischaemic stroke or heart attack and were treated with mainly aspirin after the event. For patients under the age of 65, the rates of significant bleeding requiring admission to hospital was 1.5% but these rates increased significantly with patients over age 75, increasing to 3.5%. In patients over 85, the rates were 5%. It was a significant concern that in the patients who did suffer a major bleed, whether it be gastrointestinal or intracranial, the rates of disability and death thereafter increased 10 times higher than those who had not suffered a similar fate.

It may well be that those people who suffered the aforementioned haemorrhages had more fragile capillaries and thus were more prone to bleeding. This, in itself, may be a marker for a poor prognosis and the bleeding was yet just another manifestation of a more fragile population. But, it does raise the question as to who should, and who should not, be taking low dose aspirin. Although I do not believe there are any clear-cut answers, it would be my suggestion that if you have already had a proven vascular event, have a high coronary calcium score or known significant carotid atherosclerosis, then aspirin or clopidogrel should be part of your long-term preventative management. If you have a strong family history particularly of breast or colon cancer, then low-dose aspirin would probably be of benefit as well.

But, if you have a prior history of any form of significant bleeding, bruise easily, or have a strong family history of bleeding, then it is probably better to avoid aspirin or clopidogrel as a preventative. If you have a history of prior peptic ulceration, reflux or any significant upper gastrointestinal symptoms you should certainly have a strong conversation with your treating doctors.

Thus, should aspirin be a key aspect of preventative strategies for all people? Certainly not.