Aspirin-anaemia link prompts calls for monitoring

3 minute read

Even low dose aspirin increases the risk of significant GI bleeding in older people, new research finds.

Daily low-dose aspirin increases the risk anaemia in people aged 70 and over, according to an Australian and US study.  

The findings have led to calls that older people taking aspirin every day be monitored more closely for anaemia.  

The Monash University-led study of more than 19,000 otherwise healthy people aged 70 and over found those taking daily low-dose aspirin had a 20% higher risk of anaemia compared to those taking a placebo over almost five years. 

Anaemia occurred in 51 per 1000 people taking aspirin compared to 43 per 1000 in the placebo group, according to the double-blind, randomised ASPREE (ASPirin in Reducing Events in the Elderly) trial.  

The effect of aspirin on anaemia was consistent even accounting for confounders such as age, sex, smoking status, alcohol use, prior aspirin use, and use of an NSAID or proton-pump inhibitor, the researchers said. ` 

“Whereas only a minority of participants are likely to experience major bleeding, this study demonstrates an increased risk for anaemia likely due to lesser degrees of bleeding (including occult blood loss) induced by aspirin,” the researchers said.   

“With increasing years of cumulative exposure, such ongoing blood loss may cause a substantially larger fraction of older persons who are treated with low-dose aspirin to develop anaemia.”  

Commenting on the study, RACGP spokesperson Professor Mark Morgan said the findings were important but “not altogether surprising”.  

All elderly patients on low-dose aspirin probably needed to have a blood count annually to identify anaemia, the professor of general practice said. 

Professor Morgan said the balance of harms and benefits were not in favour of using aspirin for primary prevention in older people.  

But in patients with a history of cardiovascular events, the benefits of taking daily aspirin would outweigh the risks of gastrointestinal bleeding, he said.  

“Patients who have had a cardiovascular event already are at much high risk of having a further event. For these people the protection afforded by low-dose aspirin usually outweighs the risk. 

“Low-dose aspirin reduces the risk of cardiovascular events such as heart attacks and stroke, but this is balanced by an increase in major bleeding.  

“What this paper adds is that there is also a risk of minor bleeding as demonstrated by a drop in average haemoglobin levels and an increase in the proportion of patients who become anaemic. There is a similar drop in average ferritin level indication a reduction in iron stores.” 

Lead author and haematologist, Associate Professor Zoe McQuilten from Monash University, said the risk of anaemia was likely to be higher in older adults taking aspirin who also had underlying diseases such as kidney disease. 

“Older adults are more likely to become anaemic generally and now doctors can potentially identify patients at higher risk of developing anaemia,” Associate Professor McQuilten said. 

Annals of Internal Medicine 2023, online 20 June  

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