According to a secondary analysis of the ASPREE trial, daily low-dose aspirin increased the incidence of anemia in older adults who were otherwise healthy. Over a median of 4.7 years, the incidence of anemia was found to be higher in the aspirin group compared to the placebo group. The study was carried out by Zoe McQuilten, MBBS, PhD, of Monash University in Melbourne, Australia, and colleagues. They noted that the estimated probability of having anemia within 5 years was higher for those taking aspirin compared to those on placebo. The study was published in the Annals of Internal Medicine.
The treatment effect was the same in the sensitivity analysis accounting for cancer incidence, and after adjusting for characteristics associated with increased risk for anemia. Hemoglobin levels declined in the placebo group, while those in the aspirin group had an estimated lower baseline mean and experienced a steeper decline in hemoglobin over time compared with placebo. Furthermore, participants with ferritin measures at baseline and 3 years had greater prevalence of ferritin levels less than 45 mg/L at year 3 and greater overall decline in ferritin by 11.5% versus placebo. The study found that 3% of participants in the aspirin group experienced at least one clinically significant bleeding event compared with 2.1% of those in the placebo group.
“We knew from large clinical trials, including our ASPREE trial, that daily low-dose aspirin increased the risk of clinically significant bleeding,” McQuilten told MedPage Today in an email. “From our study, we found that low-dose aspirin also increased the risk of developing anemia during the trial and this was most likely due to bleeding that was not clinically apparent.”
Impact of Anemia on Older Adults
The incidence of anemia is known to increase with age, and it’s estimated that about 17% of adults ages 65 and up are anemic, with a higher prevalence among people in nursing homes and hospitals. Prior research has shown that anemia in older adults was associated with higher overall mortality, lower quality of life, higher cardiovascular disease (CVD) incidence, greater risk of falls and fractures, and longer hospital stays, while previous results from the ASPREE trial showed associations between use of low-dose aspirin and increases in overall mortality and deaths from cancer in the elderly.
The increased health risks and costs of care tied to anemia in older adults provide further reasons to restrict the use of low-dose aspirin to those with an evidence-based indication and to monitor for development of iron-deficiency anemia in persons taking regular aspirin. The study’s findings show that occult blood loss and anemia are potential harms for older adults taking aspirin for primary prevention in addition to the known risk of major bleeding events. The U.S. Preventive Services Task Force already recommends against low-dose aspirin for primary prevention in older adults ages 60 and over.
The study found that daily low-dose aspirin increases the incidence of anemia in healthy older adults. The risks with aspirin were consistent across sex and age, and in those with chronic kidney disease, diabetes, alcohol or tobacco use, prior aspirin use, and continued use of low-dose non-steroidal anti-inflammatory drugs and proton pump inhibitors. The authors recommended restricting the use of low-dose aspirin to those with an evidence-based indication and monitoring for development of iron-deficiency anemia in persons taking regular aspirin.