Increased Risk of Anemia in Older Adults Linked to Daily Low-Dose Aspirin Usage

Daily low-dose aspirin may increase the risk of anemia in people ages 65 and older, new research shows. 

The study, published on June 20 in the Annals of Internal Medicine, adds to growing evidence that routine aspirin use for people with no heart attack history carries more risk than benefit.Taking a daily baby aspirin has become a common and effective heart attack prevention strategy for people who have had a heart attack, but it’s also popular among people with no cardiovascular disease or history of a heart attack.

A 2019 study estimated that around 29 million Americans who do not have cardiovascular disease or a history of heart attack take aspirin daily, thinking it will prevent a first heart attack. Nearly 7 million do it without the recommendation of a healthcare provider.“There is mounting data that aspirin purely for prevention may not be as beneficial as we thought, and may be more harmful than we thought,” Parag Goyal, MD, a cardiologist at Weill Cornell Medicine in New York who was not involved with the new research, told Health. 

However, Goyal stressed that the new findings only apply to people who do not have a heart condition. “If someone has had a heart attack in the past, aspirin is really important to continue,” he said.

Aspirin thins the blood, which can reduce the risk of blood clots forming in the arteries and causing a heart attack. But those blood-thinning qualities can also cause ulcers and bleeding in the gastrointestinal tract.

Because of this, researchers wanted to know if routine low-dose aspirin use in people who aren’t at high risk for a heart attack could cause anemia, a condition in which the body doesn’t have enough red blood cells to deliver oxygen to body tissues. Anemia can cause weakness, exhaustion, and irritability.

For the study, Erica Wood, MBBS, head of the Transfusion Research Unit in the department of Public Health and Preventive Medicine at Monash University in Australia, and her team analyzed data collected during the ASPREE (ASPirin in Reducing Events in the Elderly) clinical trial.

The trial included more than 19,000 people aged 65 years and older. Half of them took 100 milligrams (mg) of low-dose aspirin daily for more than four years while the other group took a placebo.

The team determined if people had anemia by examining participant blood samples. They looked at each person’s levels of ferritin—a blood protein that contains iron—and hemoglobin—a protein in red blood cells that carries oxygen. Being low in either of these proteins indicates anemia.

The researchers found that people who took daily low-dose aspirin were about 20% more likely to have anemia than those who didn’t take it. 

The cause was likely low-grade bleeding from the gastrointestinal tract that’s easy to miss, Wood told Health. 

“Sometimes these bleeds are obvious, but many times, these bleeds are very small and chronic in nature, making them more difficult to detect,” said Goyal.

Added Wood: “People taking low dose aspirin should watch out for symptoms of anemia, such as fatigue and shortness of breath, and also any signs of blood loss, and speak to their doctor if they are concerned.”

She said that the new findings do not apply to people taking aspirin as needed for pain, and echoed that people who have been advised by a physician to take daily low-dose aspirin should not stop based on the study.

Although baby aspirin has been touted for decades as an easy, over-the-counter heart attack preventative, new information collected over the past few years has caused agencies that set medical guidelines to caution against daily aspirin for many people.

In April 2022, the U.S. Preventive Services Task Force revised their recommendations for who should take daily aspirin to prevent heart attack after studies linked the medication to gastrointestinal bleeding. The updated guidelines recommend people 60 years and older do not take low-dose aspirin as a primary preventative for heart attack.

There are other options for prevention, however, both for people who have already had a heart attack and those looking to prevent their first. According to the American Heart Association (AHA), maintaining a healthy lifestyle is the most effective way to protect heart health. This includes:

For those who have already had a heart attack or are at high risk, statins may be a safer or more effective option than aspirin, said Goyal. 

“There is strong data that statins prevent heart attacks, at least in people younger than 75 years old,” he said, noting that research is still underway for people over 75. “If aspirin is being prescribed purely for prevention, it may be reasonable to stop aspirin use in some people.”