Time for a proper study of aspirin after a vascular event?

Belch et al add to the documentation that long term aspirin has little or no benefit in patients who have or are at risk of atherosclerotic cardiovascular disease.1 2

Few long term trials of aspirin have shown a reduction in mortality or major morbidity. However, editors of journals persist in publishing papers on aspirin with conclusions designed to mislead health professionals and the public.

The New England Journal of Medicine must take first place in this rogue’s gallery with publication of the US physician’s study (stopped for futility but published as a positive trial after retrospective rearrangement of the primary end point).3 Then comes the Lancet with the HOT study, which recommended aspirin despite the study being neutral on its primary end point and retrospectively redefining the criteria for myocardial infarction.4 And again with the PEP study, which showed a significant excess of fatal and non-fatal myocardial infarction when aspirin was used for prophylaxis of deep venous thrombosis after hip fracture but this worrying finding was not highlighted in the conclusions.5

The shortcomings of the aspirin meta-analysis have not been well publicised, although the BMJ has not stifled the debate totally.2 However, Belch and colleagues’ conclusion—“aspirin should, however, still be given for secondary prevention of cardiovascular disease in people with diabetes mellitus, when the evidence base is convincing, and the results of this study must not detract from this important standard of care”—should have specified the duration of aspirin prophylaxis after a vascular event for which there is evidence of benefit (about 6-12 weeks). There is no evidence of a longer term benefit with aspirin and some concern that there may be harm.

We should assess aspirin in the same way as any other therapeutic intervention. No trial shows that contemporary doses of aspirin used long term reduce mortality. Is it not time for an adequately powered study comparing short with long term aspirin 75mg/day after a vascular event?