Can aspirin (acetylsalicylic acid) be used as a prophylactic for Deep Vein Thrombosis (DVT)?

From the Guidelines

Aspirin can be used as a DVT prophylactic in certain clinical situations, particularly in patients with contraindications to standard prophylactic agents or those at lower risk of DVT. For DVT prophylaxis, low-dose aspirin (81-325 mg daily) may be used, with the most common regimen being 81 mg daily, which can be continued for the duration of the risk period 1. Aspirin works by inhibiting platelet aggregation through irreversible inhibition of cyclooxygenase-1 (COX-1), reducing the formation of thromboxane A2 and preventing platelet activation and clot formation. However, aspirin is generally considered less effective than other anticoagulants, such as low molecular weight heparins (like enoxaparin), unfractionated heparin, or direct oral anticoagulants, which are typically preferred for higher-risk patients as they provide more effective prophylaxis 1. Some key points to consider when using aspirin for DVT prophylaxis include:

• Aspirin is most appropriate for patients at lower risk of DVT or as an alternative when other anticoagulants cannot be used 1.
• Common side effects of aspirin include gastrointestinal irritation and increased bleeding risk, so patients should be monitored accordingly.
• The use of aspirin should be reevaluated when patients stop anticoagulant therapy because aspirin may have been stopped when anticoagulants were started 1. It's also important to note that extended anticoagulant therapy is estimated to reduce recurrent VTE by more than 80%, and extended DOAC therapy is associated with a risk of bleeding similar to that of aspirin, whereas aspirin will reduce the risk of recurrent VTE by about one-third 1. Therefore, the decision to use aspirin as a DVT prophylactic should be made on a case-by-case basis, taking into account the individual patient's risk factors and medical history.

From the Research

Aspirin as DVT Prophylactic

• Aspirin has been studied as a potential prophylactic for deep vein thrombosis (DVT) in various patient populations 2, 3, 4, 5.
• The evidence suggests that aspirin may reduce the risk of VTE by around 25% in high-risk surgical patients 2.
• A study published in 2020 reviewed the proposed mechanisms of aspirin in preventing venous thrombosis and the evidence for its use in primary and secondary prophylaxis of VTE 3.
• Another study published in 2023 found that adding antiplatelet agents, such as aspirin, to standard anticoagulation treatment in patients with VTE may reduce recurrence of DVT or pulmonary embolism, and may also lower the risk of post-thrombotic syndrome in patients with acute DVT 4.
• A 2024 study found that low-dose aspirin is the safest prophylaxis for prevention of VTE after total knee arthroplasty across all patient risk profiles, with decreased odds of DVT, PE, bleeding, infections, and hospitalizations compared to other prophylaxis regimens 5.

Patient Populations

• Aspirin may be beneficial in patients who require it for other reasons, such as those with high risk of arterial vascular occlusion, including patients with polycythaemia vera and essential thrombocythaemia 2.
• The evidence is less clear for patients with myeloproliferative disorders, long distance travellers, and patients receiving treatment with the IMiD class of drugs 2.
• Aspirin may be effective in reducing VTE risk in myeloma patients on IMiD drugs in combination with dexamethasone or chemotherapy 2.

Comparison to Other Prophylactics

• There is no clear evidence that aspirin is superior to anticoagulants, such as coumarins or heparin, in preventing VTE 2, 6.
• A study published in 2002 found that anticoagulants offered no net advantages over antiplatelet agents in acute ischaemic stroke, and that the combination of low-dose unfractionated heparin and aspirin may be associated with net benefits compared to aspirin alone 6.
• The 2024 study found that low-dose aspirin is a safe and effective method of prophylaxis in patients undergoing total knee arthroplasty, with decreased odds of DVT, PE, bleeding, infections, and hospitalizations compared to other prophylaxis regimens 5.