Low-dose aspirin increases anaemia risk: Study

Prolonged daily aspirin use increases the risk of anaemia in older people by 20%, a new study analysing data from the landmark ASPREE trial has found.
 
The results, which apply to people around the age of 70 and older, have prompted researchers to suggest that regular monitoring for anaemia be considered for patients taking low-dose aspirin.

The Monash University-led study, published in Annals of Internal Medicine, followed 18,153 initially healthy older adults in Australia and the US, and recorded incidents of anaemia over an average 4.7 years.

The risk of developing anaemia was found to be 20% higher in the aspirin group compared to those in the placebo group. 
 
Lead author, Associate Professor Zoe McQuilten from Monash University’s School of Public Health and Preventive Medicine, said while bleeding is a known side-effect of aspirin, few previous studies have looked at how prolonged use impacts the progressive development of anaemia in older adults.

‘This study gives a clearer picture of the additional risk of becoming anaemic with aspirin use,’ she said.
 
‘Older adults are more likely to become anaemic generally and now doctors can potentially identify patients at higher risk of developing anaemia.
 
‘The impact is likely to be greater in older adults with underlying diseases, such as kidney disease.’
 
Associate Professor McQuilten told newsGP that the increased the risk of developing anaemia was judged to be most likely due to bleeding that was not clinically apparent.
 
‘Clinicians should be aware that daily low-dose aspirin contributes to an increased risk of iron deficiency and anaemia in healthy elderly [people] and this is particularly relevant to individuals on long term aspirin,’ she said.
 
‘However, this study was conducted in the setting of primary prevention, and it does not have implications for the benefits of low dose aspirin for secondary prevention – for example, in individuals with a history of heart disease.’
 
The new research is the largest study to date that has investigated anaemia in older people as part of a randomised controlled trial, with half the participants taking a placebo and the other half a daily low dose (100 mg) of aspirin.

In addition to a higher risk of anaemia, blood tests revealed a faster decline of haemoglobin and reduced ferritin (a protein that carries iron) levels in the aspirin group compared to the placebo group.  
 
Professor Mark Nelson, a GP researcher and principal investigator on the ASPREE study who co-authored the new paper, told newsGP the findings will be of great interest to GPs who have likely observed occult anaemia in their patients taking aspirin and suspected gastrointestinal blood loss.
 
‘The rationale for the analysis in ASPREE goes back to an earlier PACE pilot study by a GP, the late Dr Chris Silagy, of 400 elderly patients,’ he said.
 
‘[Dr Silagy] observed a significant decline in haemoglobin in those taking low dose aspirin versus placebo over a 12-month period. The larger numbers and longer follow-up of ASPREE gave us the power to demonstrate the clinical adverse effects in the over-70s.
 
‘It was also thought that anaemia would be far more consequential in an elderly population due to exacerbation of conditions associated with ageing, such as heart failure and falls.
 
‘Obviously a 20% increase in anaemia would be acceptable in secondary prevention but in primary prevention, as was the case in ASPREE, this is an additional harm to the major bleeding observed.’

Anaemia is commonly experienced by older adults, potentially affecting overall function and increasing fatigue, disabilities, depressive symptoms and cognitive problems.

However, while it has been associated with a number of harms that impact its viability as primary prevention, Associate Professor McQuilten cautions that for some older adults, aspirin remains a valuable therapy to prevent recurring heart attacks or stroke.
 
‘Patients should not change their aspirin regimen without speaking to their GP,’ she said.
 
Log in below to join the conversation.

anaemia aspirin ASPREE