People who take low-dose aspirin have an increased risk of major gastrointestinal and intracranial bleeding, found a study published today in JAMA. It also showed that people with diabetes had a high rate of major bleeding, whether or not they used aspirin.
Researchers in Italy compared the risk of suffering a major gastrointestinal or intracranial bleed among 186,425 people who had been newly prescribed daily low-dose aspirin (300mg or less), with the risk among the same number of matched controls who were not using aspirin.
During 6 years’ follow up, there were 6907 first cases of major bleeding that required hospital admission – 4487 episodes of gastrointestinal bleeding and 2464 episodes of intracranial haemorrhage (44 people suffered both on the same day). People taking aspirin were 55% more likely than controls to have suffered a gastrointestinal bleed, and 54% more likely to have had intracranial bleeding.
They researchers point out that the 55% increased relative risk of major bleeding equates to about two excess cases per 1000 patients treated per year – “the same magnitude of the number of major cardiovascular events avoided in the primary prevention setting for individuals with a 10-year risk of between 10% and 20%”.
But they also found that having diabetes independently raised the risk of major bleeding episodes by 36%, irrespective of aspirin use. People with diabetes and who were not taking aspirin had a 59% increased relative risk of gastrointestinal bleeding, and a 64% relative risk of intracranial bleeding.
The study authors said: “Our study shows, for the first time, to our knowledge, that aspirin therapy only marginally increases the risk of bleeding in individuals with diabetes.
“These results can represent indirect evidence that the efficacy of aspirin in suppressing platelet function is reduced in this population.”
They went on: “In conclusion, weighing 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.”
The author of an accompanying editorial wrote: “Assessment of bleeding risk and of net clinical benefit will merit further emphasis as issues inherent to aspirin use also apply to more potent platelet inhibitors and anticoagulants; there is only a thin line between efficacy and safety, and the reduction in ischemic events comes at the cost of increased major bleedings.”