In people aged 75 or over, long–term daily aspirin use is linked to a higher than expected risk of disabling or fatal bleeding, according to a new study in The Lancet journal.

While short–term aspirin use after a stroke or heart attack has clear benefits, the authors say that patients over 75 who take aspirin on a daily basis should be prescribed a proton–pump inhibitor to reduce the risk of bleeding.

Previous studies have shown there is a causal link between antiplatelet treatment and upper gastrointestinal bleeding, and although the risk is known to increase with age, estimates on the size of the risk vary widely there are few data on whether severity of bleeding also increases with age.

Professor Peter Rothwell, lead author from Oxford University, says: "We have known for some time that aspirin increases the risk of bleeding for elderly patients. But our new study gives us a much clearer understanding of the size of the increased risk and of the severity and consequences of bleeds. Previous studies have shown there is a clear benefit of short term antiplatelet treatment following a heart attack or stroke. But our findings raise questions about the balance of risk and benefit of long–term daily aspirin use in people aged 75 or over if a proton–pump inhibitor is not co–prescribed. However, suddenly stopping medication is definitely not advised, so patients should always talk to their doctors."

The Oxford Vascular Study followed 3,166 patients who had previously had a stroke or heart attack and were prescribed antiplatelet drugs (mostly aspirin). Half the patients were aged 75 or over at the start of the study. Over 10 years of the study, a total of 314 patients were admitted to hospital for bleeding. The risk of bleeding, in particular the risk of fatal or disabling bleeding, increased with age.For patients under 65 taking daily aspirin, the annual rate of bleeds requiring hospital admission was approximately 1.5%. For patients aged 75–84, the annual rate rose to approximately 3.5% and to 5% for patients aged over 85.

Similarly, the risk of disabling or fatal bleeding increased with age. For patients aged under 65, the annual rate of life–threatening or fatal bleeds was less than 0.5%. For patients aged 75–84, the rate rose to approximately 1.5%, and to nearly 2.5% for patients aged 85 or over.

The outcome of non–fatal bleeds was also worse at older ages. The proportion of survivors for whom a bleed resulted in a new, or sustained increase in disability rose from 3% (4/157) for people aged under 75, to 25% (46/183) for people aged over 75. Overall, the risk of disabling or fatal bleeding over ten years was 10 times higher at ages 75 years or older, compared to younger patients.

Although the risk of heart attacks and strokes also increases with age, the authors conclude that for patients aged 75 or older major upper gastrointestinal bleeding as a result of antiplatelet therapy was at least as likely to be disabling or fatal as recurrent ischaemic stroke, if a proton pump inhibitor (PPI) is not co–prescribed.

PPIs could reduce upper gastrointestinal bleeding by 70–90% in patients receiving long–term antiplatelet treatment. However, prescription is not routine and only about a third of patients in the study were taking them. While there are some known risks associated with long–term PPI use, the authors conclude that the benefits of PPI use at older ages outweigh the risks, and guidelines should recommend the co–prescription of PPIs in this age group.

Professor Rothwell adds: "While there is some evidence that PPIs might have some small long–term risks, this study shows that the risk of bleeding without them at older ages is high, and the consequences significant."