From the Guidelines
Direct oral anticoagulants (DOACs) are recommended for thromboprophylaxis in patients with lower limb immobilization from the Emergency Department, as they have been shown to be non-inferior to low molecular weight heparin (LMWH) in preventing venous thromboembolism (VTE) and have a lower risk of clinically relevant bleeding 1. The preferred agents include rivaroxaban 10mg once daily, apixaban 2.5mg twice daily, or betrixaban 80mg once daily.
Key Considerations
- Treatment should typically continue for the duration of immobilization and until full weight-bearing is resumed, usually 2-6 weeks depending on the injury.
- Prophylaxis should be considered for patients with risk factors such as severe injury, complete immobilization, obesity, previous venous thromboembolism, active cancer, or age over 60 years.
- Before prescribing, assess renal function, as dose adjustments may be needed for patients with impaired kidney function.
- DOACs should be avoided in pregnant patients, those with active bleeding, severe renal impairment, or on interacting medications.
Mechanism and Advantages
- DOACs work by directly inhibiting specific coagulation factors (Factor Xa for rivaroxaban, apixaban, and betrixaban; thrombin for dabigatran), providing predictable anticoagulation with fewer drug interactions compared to traditional options like low molecular weight heparin.
- They offer the advantage of oral administration, improving compliance and eliminating the need for injections, making them particularly suitable for outpatient management from the ED.
Evidence Summary
- A 2018 study found that DOACs are non-inferior to LMWH in preventing VTE and have a lower risk of clinically relevant bleeding 1.
- A 2010 study found that thromboprophylaxis is effective in reducing the rate of VTE during immobilization of the lower extremities, with a mean rate of VTE reduced from 17.1% to 9.6% with the use of LMWH 1.
From the Research
Role of Direct Oral Anticoagulants (DOACs) in Preventing Venous Thromboembolism
- The provided studies do not directly discuss the role of Direct Oral Anticoagulants (DOACs) in preventing venous thromboembolism in patients with lower limb immobilization from the Emergency Department (ED) 2, 3, 4, 5, 6.
- However, the studies suggest that low molecular weight heparin (LMWH) and fondaparinux can reduce the risk of venous thromboembolism (VTE) in patients with lower limb immobilization 2, 4, 5, 6.
- A clinical risk assessment model, such as the TRiP(cast) score, can be used to predict VTE risk after immobilization for lower-limb trauma and guide thromboprophylaxis prescribing 3.
- The studies emphasize the importance of risk assessment and targeted thromboprophylaxis in high-risk patients to reduce the burden of preventable VTE 3, 4, 5, 6.
- Further research is needed to determine the effectiveness of DOACs in preventing VTE in patients with lower limb immobilization from the ED.
Thromboprophylaxis in Patients with Lower Limb Immobilisation
- Low molecular weight heparin (LMWH) has been shown to reduce the risk of asymptomatic deep vein thrombosis (DVT) and symptomatic VTE in patients with lower limb immobilization 2, 4, 6.
- Fondaparinux has also been found to reduce the risk of any VTE and clinically detected DVT in patients with temporary lower limb immobilization following an injury 6.
- The use of thromboprophylaxis, such as LMWH or fondaparinux, can reduce the odds of both asymptomatic and clinically detected VTE in people with temporary lower limb immobilization following an injury 6.
Risk Assessment and Targeted Thromboprophylaxis
- A clinical risk assessment model, such as the TRiP(cast) score, can be used to predict VTE risk after immobilization for lower-limb trauma and guide thromboprophylaxis prescribing 3.
- Patients with lower limb immobilization should be risk assessed, and those deemed high risk for VTE should receive prophylactic LMWH or other thromboprophylactic agents for at least the duration of cast immobilization 4, 5.