Low-dose aspirin associated with bleeding events

Daily use of low-dose aspirin was associated with an increased risk of major gastrointestinal or cerebral bleeding, a study found.

Researchers used administrative data from 4.1 million citizens in 12 local health authorities in Italy to identify a cohort of 186,425 individuals taking aspirin (daily doses of 300 mg or less) from January 2003 to December 2008 and 186,425 matched controls who didn't take aspirin.

Results appeared in the June 6 Journal of the American Medical Association. During a median follow-up of 5.7 years, there were 6,907 first episodes of major bleeding requiring hospitalization. There were 4,487 episodes of gastrointestinal bleeding and 2,464 episodes of intracranial hemorrhage.

The incidence rates of total hemorrhagic events were 5.58 (95% CI, 5.39 to 5.77) per 1,000 person-years for those on aspirin and 3.60 (95% CI, 3.48 to 3.72) per 1,000 person-years for those without aspirin use (incidence rate ratio [IRR], 1.55; 95% CI, 1.48 to 1.63). Aspirin was associated with an excess risk of gastrointestinal bleeding (IRR, 1.55; 95% CI, 1.46 to 1.65) and intracranial bleeding (IRR, 1.54; 95% CI, 1.43 to 1.67). Regardless of aspirin use, diabetes was independently associated with an increased risk of major bleeding episodes (IRR, 1.36; 95% CI, 1.28 to 1.44).

The authors noted, “[W]eighing the benefits of aspirin therapy against the potential harms is of particular relevance in the primary prevention setting, in which benefits seem to be lower than expected based on results in high-risk populations. In this population-based cohort, aspirin use was significantly associated with an increased risk of major bleeding, but this association was not observed for patients with diabetes. In this respect, diabetes might represent a different population in terms of both expected benefits and risks associated with antiplatelet therapy.”

An editorial noted that guidelines advocating the routine use of aspirin for primary prevention for individuals above a moderate level of risk of coronary heart disease should be carefully considered as this approach may not be advisable for all patients.