MEDICAL MATTERS:The blanket treatment of heart problems with aspirin needs to be considered carefully
DURING A recent continuing medical education (CME) meeting run by Irish College of General Practitioners (ICGP) tutors, a lively discussion arose as to whether the doctors present would give aspirin to a 45-year-old man who had recently been assessed following an episode of chest pain.
While no sign of blocked coronary arteries had been found by hospital doctors, the patient was a smoker, was clinically overweight and had mildly elevated cholesterol levels.
The nub of the debate among the doctors was whether aspirin was appropriate in the primary prevention of coronary heart disease.
Primary prevention refers to treatment given to a person without a particular disease, but who might benefit, based on having a higher risk of developing the condition in the future.
There is no argument among doctors as to the benefits of secondary prevention in heart disease.
It is the basis of the community based Heartwatch programme, which offers free care to people with pre-existing coronary artery disease with the aim of keeping their blood pressure and cholesterol under control.
In addition, it encourages participants to exercise well and adopt a Mediterranean- style diet.
Overall, the scheme has been successful in modifying risk factors for many people who have already had a bypass or a heart attack and who very much want to avoid a repeat visit to their local coronary care unit.
The evidence for using aspirin in secondary prevention is strong. Long-term treatment with aspirin, which helps reduce clotting by making platelets in the blood less sticky, reduces the risk of a future heart attack or stroke by about a quarter.
If aspirin is so good, why not give it to everyone over 50?
The reason for not adopting a blanket approach is the small but real risk of aspirin causing a bleed in the gastrointestinal tract (and more rarely in the brain), allied to research showing a much lower benefit in terms of prevention among those with no evidence of previous heart disease.
However, some existing guidelines appear to ignore the risk-benefit ratio of giving aspirin to a broader population and recommend that aspirin be used for primary prevention in those who appear to be at moderately raised risk of coronary heart disease in the future.
So the publication of a landmark paper in this week’s Lancet – showing that the value of long-term use of aspirin is uncertain because the benefits and risks to the population as a whole cancel each other out – is welcome. Doctors from the Clinical Trials Service Unit at the University of Oxford carried out a collective (meta) analysis of primary prevention trials involving more than 95,000 people.
They concluded that giving aspirin to people with no proven history of heart disease reduced the risk of a non-fatal heart attack by 12 per cent but had no real effect on the incidence of stroke or death from any cardiovascular cause.
However, the small risk of internal bleeds increased by about a third in those taking aspirin compared with a control group who did not take the drug.
Why should we take particular notice of this research when other data has come down (marginally) in favour of an aspirin for all policy?
A big plus in its favour is that the analysis of so many people was carried out on an individual patient basis, rather than just looking at overall numbers, which makes this study more relevant for the individual deciding whether to take an aspirin a day or not.
In the words of the lead author, Prof Colin Baigent, “We don’t have good evidence that, for healthy people, the benefits of long-term aspirin exceed the risks by an appropriate margin”.
It is also a vindication of the need to place drug safety at the top of our prescribing agenda: and of those doctors who, at the recent meeting, argued against aspirin for the man with some cardiovascular risk factors but no evidence of established heart disease.
Dr Houston is pleased to hear from readers at mhouston@irishtimes.com but regrets he is unable to reply to individual medical queries
