The Drugs and Therapeutics Bulletin has published a review of the available evidence for aspirin in the primary prevention of cardiovascular disease (CVD) and concluded that use in this way is unjustified. This advice has been reported in the general media (BBC).
This review considers the recommendations made in various current guidelines and the historical evidence base in comparison to more recent research including the analysis conduct by the Antithrombotic Trialists’ Collaboration and published in the Lancet earlier this year.
A gender specific analysis that is considered found an absolute benefit of 4 cardiovascular events prevented in 1,000 women and 3 prevented in men over a 6.4 year period. This benefit was offset by 2.5 additional bleeding events per 1,000 women and 3 events in men.
These same data can be expressed in terms of number needed to treat (NNT) to prevent a cardiovascular event and number needed to treat to cause a harm (NNH) of a bleeding event. In women the NNT is 333 and the NNH is 400 while in men the figures are 270 and 303 respectively.
The authors of this review conclude that, "the currently available evidence does not justify the routine use of low-dose aspirin for the primary prevention of CVD in apparently healthy individuals, including those with elevated blood pressure or diabetes". They recommend reviewing patients currently taking aspirin for primary prevention and advise against starting any new patients on primary prevention treatment with aspirin.
Action: Clinicians should be aware of this review and the media coverage it has generated. The balance of risk and benefit of aspirin in primary prevention appears to be a very fine line and continued use appears unjustified.