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The New USPSTF Recommendation Regarding Aspirin Use to Prevent Cardiovascular Disease
TAKE-HOME MESSAGE
- The new USPSTF guidelines do not recommend routine preventive aspirin for everyone. The USPSTF recommends that the decision to initiate low-dose aspirin for the primary prevention of cardiovascular disease (CVD) events in adults 40–59 years who have a 10% or greater CVD risk with no increased risk for bleeding is an individual one between physician and patient, with moderate certainty that that the net benefit is small. The USPSTF recommends against initiating low-dose aspirin use for the primary prevention of CVD in patients aged 60 or older.
- This study showed that aspirin use for primary prevention of CVD events was associated with a decreased risk of myocardial infarction and stroke, but was not associated with a significant decrease in CVD mortality or all-cause mortality. Low-dose aspirin use was associated with significantly higher risk for gastrointestinal bleeding and intracranial bleeding. These recommendations explicitly refer to initiation of aspirin, and patients currently taking aspirin should not discontinue it without consulting their clinician.
abstract
This abstract is available on the publisher's site.
Access this abstract nowImportance
Cardiovascular disease (CVD) is the leading cause of mortality in the US, accounting for more than 1 in 4 deaths. Each year, an estimated 605 000 people in the US have a first myocardial infarction and an estimated 610 000 experience a first stroke.
Objective
To update its 2016 recommendation, the US Preventive Services Task Force (USPSTF) commissioned a systematic review on the effectiveness of aspirin to reduce the risk of CVD events (myocardial infarction and stroke), cardiovascular mortality, and all-cause mortality in persons without a history of CVD. The systematic review also investigated the effect of aspirin use on colorectal cancer (CRC) incidence and mortality in primary CVD prevention populations, as well as the harms (particularly bleeding) associated with aspirin use. The USPSTF also commissioned a microsimulation modeling study to assess the net balance of benefits and harms from aspirin use for primary prevention of CVD and CRC, stratified by age, sex, and CVD risk level.
Population
Adults 40 years or older without signs or symptoms of CVD or known CVD (including history of myocardial infarction or stroke) who are not at increased risk for bleeding (eg, no history of gastrointestinal ulcers, recent bleeding, other medical conditions, or use of medications that increase bleeding risk).
Evidence Assessment
The USPSTF concludes with moderate certainty that aspirin use for the primary prevention of CVD events in adults aged 40 to 59 years who have a 10% or greater 10-year CVD risk has a small net benefit. The USPSTF concludes with moderate certainty that initiating aspirin use for the primary prevention of CVD events in adults 60 years or older has no net benefit.
Recommendation
The decision to initiate low-dose aspirin use for the primary prevention of CVD 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. (C recommendation) The USPSTF recommends against initiating low-dose aspirin use for the primary prevention of CVD in adults 60 years or older. (D recommendation).
Additional Info
Disclosure statements are available on the authors' profiles:
Aspirin Use to Prevent Cardiovascular Disease: US Preventive Services Task Force Recommendation Statement
JAMA 2022 Apr 26;327(16)1577-1584, , KW Davidson, MJ Barry, CM Mangione, M Cabana, D Chelmow, TR Coker, EM Davis, KE Donahue, CR Jaén, AH Krist, M Kubik, L Li, G Ogedegbe, L Pbert, JM Ruiz, J Stevermer, CW Tseng, JB WongFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
ASA in primary prevention patients – to use or not to use? That is the question
In secondary prevention patients, blood clots have been shown to form so using aspirin (ASA) to protect against clot formation in these patients clearly makes sense. However, for primary prevention patients, we need to closely examine the risks and benefits of ASA use.
ASA blocks the COX-1 enzyme, which converts arachidonic acid into prostaglandins. In platelets, COX-1 helps in the synthesis of prostaglandins, which help in blood clot formation. Blocking this pathway would reduce clot formation, thereby reducing myocardial infarctions (MI) and ischemic strokes. However, excessive blockade of this pathway could lead to bleeding complications, such as hemorrhagic stroke or gastrointestinal (GI) bleeding. In the stomach, COX-1 helps in synthesizing prostaglandins that protect the gastric mucosa; blocking COX-1 in the stomach could lead to more ulcerations and GI bleeding in addition to the platelet effects. Therefore, a balance needs to be maintained between preventing cardiovascular (CV) events and bleeding complications.
In older studies on ASA, people had several CV risks because they were not on statins or ACE inhibitors and smoking was more prevalent; effectively, plaques would grow unimpeded and eventually rupture. If you had ASA on board, it stopped the blood clot from forming and protected you against myocardial infarction.
However, in newer studies on ASA, people are well treated. They are administered statins, their blood pressure is well controlled, and smoking is less prevalent. Hence, the growth of the plaques has been significantly slowed down and they are less likely to rupture. If there are fewer ruptures then there are no clots and hence ASA cannot come to the rescue.
However, the bleeding risk from ASA has not been reduced. The benefits of CV event reduction are less but the bleeding risk of ASA is still the same. When the US Preventive Services Task Force (USPSTF) added these new ASA studies into the mix, the risks and benefits of ASA become less favorable.
The USPSTF still observed benefits with ASA use. Non-fatal MI was reduced by 12% (OR, 0.88), non-fatal ischemic stroke was reduced by 12% (OR, 0.88), and death occurred rarely. Unfortunately, the bleeding risk was still there with ASA. Major gastrointestinal bleeding was increased by 58% (OR, 1.58) and intracranial bleeding was increased by 31% (OR, 1.31).
Based on absolute numbers, the risk outweighs the benefits. However one could argue that the impact of a GI bleed is not the same as an ischemic stroke. Just like you could argue that a hemorrhagic stroke is not the same as an MI. Therefore, just counting events does not capture the impact of these events.
The USPSTF took these data and created a mathematical model to figure out where the best risk–benefit ratio was. The USPSTF concluded that patients aged between 40 to 59 years, who have a 10-year CVD risk >10%, and who are not at an increased risk for bleeding would most likely benefit; this was a grade C recommendation. In other words, not very strong data. In addition, they recommended against starting low-dose aspirin for the primary prevention of CVD in adults aged ≥60 years—grade D recommendation. Again, not great data.
What should we do? For our patients, we should ensure that they are optimized for all their risk factors—lipids, blood pressure, smoking, diabetes, etc. Then ASA becomes optional and we can avoid the bleeding risk from ASA. Remember, this is about starting ASA. None of these studies looked at stopping ASA. That is an issue for another day.
In the end, it is all about the risks and benefits. What will harm my patients first—is it a blood clot or a bleed? This is the question we should be asking.