Aspirin lowers the risk of recurring blood clots in the INSPIRE study

Aspirin lowers the risk of recurring blood clots in the INSPIRE study

Professor John Simes, CTC director, appeared nationally on Channel 9 news and ABC radio yesterday to explain the implications of the news that low-dose aspirin reduces the risk of recurrence of blood clots in the veins.

The results come from INSPIRE, a study just published by the CTC and its international colleagues.

Professor Simes, chair of the INSPIRE group, said: 'The study provides clear, consistent evidence that low-dose aspirin can help to prevent new venous blood clots and other cardiovascular events among people who are at risk because they have already suffered a blood clot.

'The treatment effect of aspirin is less than with warfarin or other new-generation direct thrombin inhibitors, which can achieve more than an 80 per cent reduction in adverse circulatory and cardiopulmonary events. But aspirin represents a useful treatment option for patients who are not candidates for anticoagulant drugs because of the expense or the increased risk of bleeding associated with anticoagulants.

'Aspirin will be ideal in the many countries where prolonged anticoagulant treatment is too expensive. A major benefit of this treatment is its cost-effectiveness. Aspirin is cheap, but it will save the treatment costs of the many recurrent clots that are prevented. This could mean a saving of millions of healthcare dollars worldwide.'

Most people who have had a blood clot in a leg vein (deep-vein thrombosis) or an embolism (where the clot blocks the blood flow) have anticoagulant drug treatment (such as warfarin) for at least 6 months, first to dissolve the clot and then to prevent it happening again.

Long-term anticoagulant drugs require frequent regular blood tests and adjustments to the dosage. Also, there is a risk that the treatment could cause bleeding in some patients. For people who are not able to cope with this, the viable alternative of taking regular aspirin will be a great benefit.

THe findings of the INSPIRE study represent the combined analyses of two trials, ASPIRE and WARFASA. ASPIRE had 822 participants from Australia, New Zealand, Singapore, India and Argentina, followed up for an average of 3 years, and WARFASA another 402 patients followed up for at least 2 years.

The combined analysis showed that 100 mg aspirin a day compared with placebo reduced the risk of further blood clots in the veins by more than a third. Those with a higher risk, such as men and those at an older age, were more likely to benefit.

Treatment was safe, with no significant bleeding associated with aspirin treatment.

Simes J, Becattini C, Agnelli G, Eikelboom J, Kirby AC, Mister R, Prandoni P, Brighton TA, for the INSPIRE (International Collaboration of Aspirin Trials for Recurrent Venous Thromboembolism) Study Investigators. Aspirin for the prevention of recurrent venous thromboembolism: the INSPIRE collaboration. Circulation. Published online 26 Aug 2014.

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27 August 2014