June 6th, 2012
Real-World Bleeding Risk with Aspirin in Primary Prevention Examined
A new study published in JAMA provides substantial new evidence about the real-world effects of aspirin, including the risk for bleeding, in a broad population. The study also sheds important new light on the effects of aspirin in a diabetic population.
Giorgia De Berardis and colleagues analyzed data from more than 4 million people in Puglia, Italy and compared 186,425 people taking low-dose aspirin with the same number of matched controls not taking aspirin.
Major bleeding events requiring hospitalization:
- aspirin: 5.58 (5.39-5.77) per 1000 person-years
- controls: 3.60 (3.48-3.72) per 1000 person-years
- Incidence rate ratio (IRR) 1.55 (1.48-1.63)
Diabetics overall had an increased risk for major bleeding episodes, but this increased risk was not significantly associated with aspirin use:
- Hemorrhagic events in diabetics overall (compared with nondiabetics): IRR 1.36 (1.28-1.44)
- Hemorrhagic events in diabetics taking aspirin compared with diabetics not taking aspirin: IRR 1.09 (0.97-1.22)
The authors write that their findings demonstrate that bleeding events occur more frequently than had been observed in clinical trials. They calculate that for individuals with a 10-year risk for cardiovascular events between 10% and 20%, the risks and benefits of aspirin therapy are similar, causing two excess bleeds, and preventing two CV events, for every 1000 people treated each year.
In an accompanying editorial, Jolanta Siller-Matula writes that the benefits of aspirin in secondary prevention are “not disputed,” since aspirin can prevent six major vascular events at the expense of one major bleeding event. But there is no such consensus for primary prevention, and Siller-Matula writes that the findings of the Italian study reinforce current European guidelines, which do not recommend aspirin for primary prevention.
The JAMA study provides far more information about aspirin use in diabetics than had been previously available. Nevertheless, writes Siller-Matural, the decision whether to use aspirin for primary prevention in this population is still not clear, and will require additional data from ongoing studies.