Taking a daily aspirin might heighten the risk of anaemia in older people, adding to existing research challenging the long-established recommendation of aspirin as a preventative therapy for dangerous cardiac events, with the findings the first ever to show a risk of minor blood related conditions in regular users.
The results come just a year after a national independent task force updated formal recommendations in April 2022 cautioning those over 60 against beginning a daily aspirin regimen.
For decades, aspirin has been used like a vitamin by a sizeable portion of America’s ageing population after research from the 1950s showed a daily low dose of the anti-inflammatory medication could help prevent diseases like heart attacks and stroke.
Eventually, reports TIME, the benefits of the routine became common knowledge, and older adults added the over-the-counter medication to their pill boxes without any sort of formal physician recommendation.
In 2021, 45% of Americans over 75 reported taking daily low doses of aspirin. Its health benefits and low cost have made it the most widely used medication in the world.
However, those benefits were mostly observed in studies of relatively young cohorts. In recent years, research has focused on the older populations most likely to use aspirin regularly, and has found that a daily aspirin regimen has been linked to more major bleeding events, like aneurysms, often at a rate that exceeds the risk of heart disease that aspirin use is intended to prevent.
The latest research is published in the Annals of Internal Medicine.
As part of the the National Institutes of Health-funded Aspirin in Reducing Events in the Elderly (ASPREE) study, a team of researchers in the US and Australia recruited more than 18 000 people over 65, and gave them all either 100mg of aspirin or a placebo pill daily for nearly five years.
When accounting for other major diseases, bleeding events, and health factors represented in the group, the team found those taking aspirin were 20% more likely to be anaemic than those who didn’t.
Anaemia, a disorder in which the body runs low on the red blood cells required to transport oxygen throughout the body, can have several consequences in the elderly. Common anaemia symptoms like fatigue, low blood pressure, and high heart rate can be extra risky for the elderly.
In the case of aspirin use, related anaemia would more than likely be caused by slower blood loss due to aspirin’s anti-clotting effects, either via minor injury or light internal bleeding. This can also lead to serious iron deficiencies.
Researchers found the participants taking aspirin also had lower levels of haemoglobin and ferritin, two important proteins that help blood cells carry oxygen.
Because of this, they recommend that older adults who take aspirin, particularly those with existing chronic conditions that put them at increased risk for anaemia, receive regular blood testing to ensure that their haemoglobin levels remain within a safe range.
Study details
Effect of Low-Dose Aspirin Versus Placebo on Incidence of Anemia in the Elderly:
A Secondary Analysis of the Aspirin in Reducing Events in the Elderly Trial
Zoe McQuilten, Le Thi Phuong Thao, Michael Bailey, John McNeil, et al.
Published in The Annals of Internal Medicine on 20 June 2023
Abstract
Background
Daily low-dose aspirin increases major bleeding; however, few studies have investigated its effect on iron deficiency and anaemia.
Objective
To investigate the effect of low-dose aspirin on incident anaemia, haemoglobin, and serum ferritin concentrations.
Design
Post hoc analysis of the ASPREE (ASPirin in Reducing Events in the Elderly) randomised controlled trial.
Setting
Primary/community care in Australia and the United States.
Participants
Community-dwelling persons aged 70 or older (≥65 years for black and Hispanic persons).
Intervention
100mg of aspirin daily or placebo.
Measurements
Haemoglobin concentration was measured annually in all participants. Ferritin was measured at baseline and three years after random assignment in a large subset.
Results
A total of 19 114 people were randomly assigned. Anaemia incidence in the aspirin and placebo groups was 51.2 events and 42.9 events per 1000 person-years, respectively (hazard ratio, 1.20 [95% CI, 1.12 to 1.29]). Haemoglobin concentrations declined by 3.6 g/L per 5 years in the placebo group and the aspirin group experienced a steeper decline by 0.6 g/L per 5 years (CI, 0.3 to 1.0 g/L). In 7139 participants with ferritin measures at baseline and year 3, the aspirin group had greater prevalence than placebo of ferritin levels less than 45 µg/L at year 3 (465 [13%] vs. 350 [9.8%]) and greater overall decline in ferritin by 11.5% (CI, 9.3% to 13.7%) compared with placebo. A sensitivity analysis quantifying the effect of aspirin in the absence of major bleeding produced similar results.
Limitations
Haemoglobin was measured annually. No data were available on causes of anaemia.
Conclusion
Low-dose aspirin increased incident anaemia and decline in ferritin in otherwise healthy older adults, independent of major bleeding. Periodic monitoring of haemoglobin should be considered in older people on aspirin.
TIME article – Using Aspirin Every Day May Cause Anaemia in Seniors (Open access)
See more from MedicalBrief archives:
Daily aspirin increases risk of falls in the elderly – ASPREE trial
Aspirin reduces cardiovascular events in elderly with raised Lp(a) – ASPREE analysis
Regular aspirin could lower colorectal cancer risk – US study