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Is it the final nail in the coffin for aspirin in primary prevention?

By Bianca Nogrady
The findings of two studies presented at the recent European Society of Cardiology Congress in Munich may have hammered the final nail in the coffin for the use of aspirin in primary prevention of cardiovascular disease (CVD).

The first study – the ARRIVE (Aspirin to Reduce Risk of Initial Vascular Events) study, also published in The Lancet – was a randomised, double-blind, placebo-controlled study of 100 mg aspirin daily for primary prevention in 12,546 individuals aged over 55 years at average risk of CVD.

There was no significant difference between the aspirin and placebo groups in the composite primary endpoint of time to first occurrence of CV death, myocardial infarction, unstable angina, stroke or transient ischaemic attack. However, there was a more than twofold higher incidence of gastrointestinal bleeding events (mostly mild) in the aspirin group than in the placebo group. The researchers noted that although the study population had a mean Framingham 10-year risk of 13.9% to 14.1%, the actual event rate was much lower: 8.43% in the aspirin group and 8.8% in the placebo group.

The second study – the ASCEND (A Study of Cardiovascular Events in Diabetes) trial, also published in The New England Journal of Medicine – compared the effect of low-dose aspirin (100mg daily) with placebo in 15,480 adults with diabetes but without known CVD.

In this patient population, aspirin was asso- ciated with a significant 1.1% reduction in the absolute risk of serious vascular events com- pared with placebo (8.5% vs 9.6%, respectively) but this was countered by a 0.9% increase in the incidence of serious bleeding events (4.1% vs 3.2%, respectively).

‘On the basis of these assumptions, the predicted number of serious vascular events that would be avoided by participants actually taking aspirin was closely balanced by the predicted number of major bleeding events caused, even among persons who had a five-year vascular risk of 10% or more,’ the researchers wrote.

Cardiologist Professor Leonard Arnolda, Clinical Director of the Illawarra Health and Medical Research Institute, Wollongong, told Cardiology Today the studies confirmed the view that the risks and benefits of aspirin for primary prevention are balanced.

‘For primary prevention, there have never been good data, so all the guidelines say there is no evidence of benefit,’ he said.

The only remaining question was whether there might still be certain subgroups where the benefits would outweigh the risks. However, Professor Arnolda said continued slicing into subgroup analyses would likely find an effect purely as a function of mathematical probabilities.
Lancet 2018;
N Engl J Med 2018; doi: 10.1056/NEJMOA1804988