In a recent publication in the Journal of the American Medical Association Network Open, findings from a clinical trial involving older adults discovered that among individuals randomized to aspirin (ASA), there was a statistically noteworthy 38% increase in intracranial bleeding resulting from a combination of hemorrhagic stroke and other causes of intracerebral hemorrhage.

The researchers sought to determine the risks of ischemic stroke and intracranial bleeding among healthy older individuals receiving daily low-dose aspirin.

The authors wrote, “Low-dose aspirin has been widely used for primary and secondary prevention of stroke. The balance between potential reduction of ischemic stroke events and increased intracranial bleeding has not been established in older individuals.”

The study was a secondary analysis of the Aspirin in Reducing Events in the Elderly randomized, double-blind, placebo-controlled trial of daily low-dose aspirin, which was conducted among 19,114 community-dwelling individuals living in Australia or the United States.

Of the 19,114 participants, 10,782 were females (56.4%); median (interquartile range [IQR]) age, 74 (71.6-77.7) years; 901 African American (4.7%), 164 Asian (0.9%), 488 Hispanic (2.6%), 17,450 Caucasian (91.3%), and 111 other race or ethnicity (0.6%).

Participants did not have a disability or known cardiovascular disease (i.e., atrial fibrillation, stroke, acute ischemic attack, or myocardial infarction) at baseline, and blood pressure was adequately controlled. The patients were randomized to receive 100 mg ASA daily or placebo. A total of 9,525 individuals received aspirin, and 9,589 individuals received a placebo.

Recruitment transpired between 2010 and 2014, and participants were followed up for a median (IQR) of 4.7 (3.6-5.7) years. This analysis was completed from August 2021 to March 2023.

Predetermined secondary outcomes were stroke and stroke etiology and were presented with a focus on the prevention of initial stroke or intracranial bleeding event. Outcomes were evaluated by review of medical records.

The results revealed that ASA did not generate a statistically significant reduction in the incidence of ischemic stroke; however, a statistically significant rise in intracranial bleeding was observed among individuals allocated to the ASA group (108 individuals [1.1%]) compared with those receiving placebo (79 individuals [0.8%]). Moreover, the authors noted that this transpired by an increase in a combination of subdural, extradural, and subarachnoid bleeding with ASA compared with placebo (59 individuals [0.6%] vs. 41 individuals [0.4%] and hemorrhagic stroke was documented in 49 individuals [0.5%] allocated to the aspirin group compared with 37 individuals [0.4%] in the placebo group).

The authors wrote, “The findings suggest that low-dose aspirin may have no role for the primary prevention of stroke and that caution should be taken with use of aspirin in older persons prone to head trauma (e.g., from falls).”

Based on their findings, the authors concluded, “In this secondary analysis of a randomized clinical trial of older adults, there was no statistically significant benefit from aspirin in preventing stroke or any conventional stroke etiological subtype. However, aspirin significantly increased the overall risk of intracranial bleeding. These data support the recommendation of the USPSTF [United States Preventive Services Task Force] that low-dose aspirin should not be prescribed for primary prevention in healthy older adults.”

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