Warfarin versus aspirin for stroke prevention

A study tracking nearly 1,000 over-75s at high risk of stroke has found that the anticoagulant drug warfarin cuts the risk by half in this older population without causing more side-effects than alternatives.

The patients in the trial had a heart complaint called atrial fibrillation – an abnormal heart rhythm – which is a major risk factor for stroke. 12% of over-75s are affected by this condition.

While warfarin has been hailed as the best approach in younger people, its blood-thinning properties were feared to pose greater risks to the very old, potentially causing severe bleeds.

In an effort to assess the suitability of warfarin for stroke prevention in this specific population, Medical Research Council researchers at the University of Birmingham found the drug was twice as effective as aspirin while being no more dangerous. Their findings are published in The Lancet .

Another major risk factor is increasing age. Hence managing the risk of stroke in older populations is crucial. Yet until now no large trial had been conducted to look at the risks and benefits of the two main methods of reducing stroke risk – aspirin and warfarin – exclusively in those over 75 years of age.

Although trials had found that warfarin was more effective than aspirin in previous trials, older patients had been severely under-represented in these trials and concerns that the anticoagulant would lead to greater instances of severe haemorrhaging put off many doctors from prescribing warfarin to older patients.

The Birmingham Atrial Fibrillation Treatment of the Aged Study (BAFTA), led by Dr Jonathan Mant and Professor Richard Hobbs at the University of Birmingham tracked over-75s being treated with either aspirin or warfarin over three years. Among those given warfarin, 24 suffered strokes, other brain haemorrhages or clots, compared with 48 of those on aspirin, making warfarin twice as effective.

What is more they found no evidence that warfarin was more hazardous than aspirin in this specific age-group, with the number of bleeding events the same in both groups. There was no difference in the mortality of the two groups.

In a time when questions are often raised as to how representative clinical trials are of the populations drugs are aimed at, particularly with regard to age, the Birmingham team were concerned to make sure the treatments for stroke prevention were assessed for both effectiveness and safety in this particularly vulnerable age-group.

“Our results show that warfarin could safely be used much more widely in this age group. I hope GPs, who manage stroke risk in most elderly people day to day will now feel more confident in prescribing this much more effective treatment to this particularly vulnerable group of patients. Our findings show that anticoagulants should be prescribed for all people aged over 75 with atrial fibrillation, unless the patient decides that the benefit is not worth the inconvenience of treatment, or there are contra-indications to use of the drug” said Dr Jonathan Mant.

Publication Details

Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Study, BAFTA): a randomised controlled trial

Jonathan Mant, FD Richard Hobbs, Kate Fletcher, Andrea Roalfe, David Fitzmaurice, Gregory YH Lip, Ellen Murray. Lancet 11 August 2007

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