Aspirin is well over 100 years old, but scientists are still trying to figure out if it should be used to prevent heart attacks and strokes. The US Preventive Services Task Force (USPSTF) was created in 1984. It “…is an independent, volunteer panel of national experts in prevention and evidence-based medicine. The Task Force works to improve the health of people nationwide by making evidence-based recommendations about clinical preventive services…” Sounds great, but when it comes to its position on aspirin for your heart, the USPSTF “trajectory has been tortuous.” That’s the conclusion of an editorial in JAMA (April 26, 2022).
Aspirin for Your Heart Has Been a Roller Coaster Ride:
The Physicians’ Health Study was published in the New England Journal of Medicine on July 20, 1989. In involved 22,071 healthy male doctors. They were randomized to take either one regular-strength aspirin tablet (325 mg) every other day or placebo. The average follow-up time was 60.2 months.
The researchers found:
“There was a 44 percent reduction in the risk of myocardial infarction [heart attack] in the aspirin group (254.8 per 100,000 per year as compared with 439.7 in the placebo group).”
There was a follow-up analysis of the physicians in this group who had “chronic stable angina.” In other words, they had chest pain on exertion or after emotional stress. In this higher-risk group, there was an 87% reduction in heart attacks among the men randomized to take aspirin (Annals of Internal Medicine, May 15, 1991).
The highly regarded authors concluded:
“Our data indicated that alternate-day aspirin therapy greatly reduced the risk for first myocardial infarction among patients with chronic stable angina, a group of patients at high risk for cardiovascular death.”
Since the Physicians’ Health Study, there have been many more randomized controlled trials of aspirin. The results have been conflicting and the recommendations from the USPSTF have been “tortuous.”
Aspirin For Your Heart: Yes, Maybe, No:
“The US Preventive Services Task Force (USPSTF) issued its first Guide to Clinical Preventive Services in 1989. That initial monograph included a recommendation to ‘consider’ aspirin prophylaxis for primary cardiovascular prevention in men 40 years or older with coronary risk factors and low bleeding risk” (JAMA, April 26, 2022).
In 1996 the USPSTF changed its mind about aspirin for your heart:
The experts concluded that the pros and cons of aspirin were too close to give the drug its blessing for heart attack prevention.
In 2002 the USPSTF modified its stance on aspirin yet again after three more studies were published. This time the task force suggested that doctors discuss the use of aspirin to prevent heart attacks in high-risk heart patients after consulting risk calculators.
“In 2009, the USPSTF went further when it strongly and specifically recommended aspirin prophylaxis be encouraged for a broad range of adults (men aged 45-79 years; women aged 55-79 years) according to estimated 10-year risk for myocardial infarction, stroke, and gastrointestinal bleeding…” (JAMA, April 26, 2022).
In April of 2016 the United States Preventive Services Task Force put out a new recommendation regarding aspirin. These experts suggested that low-dose aspirin use could prevent heart attacks, strokes and colorectal cancer. The benefits were “modest” and there was a risk of bleeding. The task force suggested that only people with a high risk of heart disease over the next 10 years and who did not have an increased risk for hemorrhage should consider aspirin prevention.
Then a study in The Lancet (July 12, 2018) analyzed data from 10 trials. The authors concluded that low-dose aspirin was ineffective for people weighing more than 154 pounds.
Then a new meta-analysis published in JAMA (Jan. 22, 2019) reviewed the results of 13 placebo-controlled trials with a total of more than 160,000 participants and over 1 million participant-years. The authors found that people taking aspirin were significantly less likely to suffer heart attacks, strokes or death from cardiovascular causes.
On April 26, 2022 the USPSTF reviewed the latest evidence and concluded (JAMA, April 26, 2022):
“Low-dose aspirin was associated with small absolute risk reductions in major cardiovascular disease events and small absolute increases in major bleeding.”
Another Adjustment in the Latest USPSTF Recommendations about Aspirin for Your Heart:
The task force then made the following recommendation (JAMA, April 26, 2022):
“The decision to initiate low-dose aspirin use for the primary prevention of CVD [cardiovascular disease] in adults aged 40 to 59 years who have a 10% or greater 10-year CVD risk should be an individual one. Evidence indicates that the net benefit of aspirin use in this group is small. Persons who are not at increased risk for bleeding and are willing to take low-dose aspirin daily are more likely to benefit. The USPSTF recommends against initiating low-dose aspirin use for the primary prevention of CVD in adults 60 years or older.”
What Does That Mean?
After reviewing all the studies and modeling the benefits and risks, the task force recommends that doctors consult with patients between 40 and 59 years old. For those with a 10 percent chance of cardiovascular disease over the next 10 years, low-dose aspirin may make sense.
But only people unlikely to have a bleeding problem should try this, since aspirin can also increase that risk. Moreover, the task force suggests that aspirin to prevent an initial heart attack does not make sense for people over 60. The benefit for the younger age group was modest.
Aspirin For Your Heart? Should You or Shouldn’t You?
We cannot answer the above question on a global basis. And each individual will need to discuss this question with her primary care provider. That said, let’s drill down on the data. The JAMA (Jan. 22, 2019) study did an excellent job in providing absolute benefit and risk data. We only wish more research was presented this way.
The absolute risk reduction with aspirin was small, just 0.4 percent. How did the researchers come up that number? Please pay careful attention. This gets complicated.
The investigators analyzed the data for primary outcomes. Primary = death from cardiovascular causes, nonfatal heart attacks and nonfatal strokes. There were 3,072 such events in the no aspirin group and 2,911 events in the aspirin-taking group. That was an 11% reduction in events. But 265 people would have needed to take aspirin to prevent one event.
Here’s another way to think of this benefit. There were 61.4 events per 10,000 participant-years in the no aspirin group. There were 57.1 events per 10,000 participant-years in the aspirin group. That was a statistically significant reduction in cardiovascular events, but as you can see, not that impressive.
How Dangerous Is Aspirin for your Heart?
The analysis also considered whether people taking aspirin were more likely to experience major bleeding. They were, although here too the difference was small, about 0.5 percent. The risk and benefit were almost evenly matched.
There were 23.1 major bleeding events per 10,000 participant-years in the aspirin-taking people and 16.4 serious bleeding events per 10,000 participant-years in the no-aspirin group.
Making Decisions About Aspirin for Your Heart:
The relatively small benefits and risks make a decision to use aspirin more complicated, especially for people without heart disease.
The authors of the JAMA (Jan. 22, 2019) study note:
“Consequently, the decision to use aspirin for primary prevention may need to be made on an individual basis, accounting for the patient’s risk of bleeding and their views on the balance of risk vs benefit.”
An editorial in the same issue of JAMA notes that:
“Because weighing the risks and benefits of aspirin in primary prevention is complicated, it should involve a shared decision-making discussion between the patient and the clinician.”
The bottom line seems to be that if your risk of a serious cardiovascular event is pretty high, low-dose aspirin could be modestly beneficial. If, on the other hand, your risk of bleeding is high, then the equation shifts against aspirin. Sorry…we warned you that it’s complicated. When it comes to aspirin there are no easy answers. You can read more about the benefits and risks of aspirin here.