The benefit of low-dose aspirin therapy for the primary prevention of cardiovascular disease is modest, and the risk of hemorrhage may offset the benefit. De Berardis and colleagues evaluated the bleeding risk attributable to prophylactic aspirin use and how diabetes affects that risk.

In a population-based cohort study using data on 4.1 million Italian citizens, 186,425 patients newly prescribed low-dose aspirin (300 mg or less) were matched with controls who weren't prescribed aspirin. The researchers found that aspirin use increased the relative risk of major gastrointestinal or intracranial bleeding episodes by 55%, which translates into two excess cases per 1,000 patients treated per year. Over a median follow-up of 5.7 years, the overall incidence rate of hemorrhagic events was 5.58 per 1,000 person-years among the aspirin users, compared with 3.60 among controls. Aspirin use was associated with an increased risk of bleeding in most subgroups. However, patients with diabetes had an elevated risk of bleeding that was not associated with aspirin use.

Other factors associated with a greater risk of bleeding were older age, male sex, hypertension, previous cardiovascular problems, and use of antiplatelet agents and anticoagulants. Statin use was associated with a lower risk of bleeding.

The rate of bleeding associated with aspirin use in this study was higher than that reported in previous clinical trials and, according to the authors, is useful for assessing the risks and benefits of low-dose aspirin therapy in a real-world setting. The study also suggests that patients with diabetes represent a different population in terms of the risks and benefits of antiplatelet therapy.-KR

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