From the Guidelines
The best anticoagulation strategy in obesity involves weight-based dosing adjustments and careful monitoring, with a preference for direct oral anticoagulants (DOACs) like apixaban 5mg twice daily or rivaroxaban 20mg daily for most obese patients with standard indications, as recommended by the European Society of Cardiology working group on cardiovascular pharmacotherapy and the European Society of Cardiology working group on thrombosis 1.
Key Considerations
- For low molecular weight heparins (LMWH) like enoxaparin, actual body weight should be used for dosing, with standard prophylactic doses of 40mg daily often increased to 40mg twice daily for BMI >40 kg/m², as suggested by a recent meta-analysis including 11 studies of class >4 obese patients hospitalized for medical or surgical conditions 1.
- For therapeutic anticoagulation, enoxaparin 1mg/kg twice daily is recommended, with consideration of anti-Xa monitoring for patients >150kg, to ensure adequate anticoagulation and minimize the risk of bleeding.
- DOACs can be used in obesity, with apixaban and rivaroxaban being the most studied, and their efficacy and safety profiles are similar to those in non-obese patients, as reported in the ENGAGE-AF and ROCKET-AF trials, respectively 1.
- Warfarin can also be used in obese patients, with standard dosing protocols and close INR monitoring targeting 2-3 for most indications, as recommended by the International Society on Thrombosis and Haemostasis.
Monitoring and Adjustments
- Medication efficacy should be monitored closely, particularly in patients with BMI >40 kg/m² or weight >120kg, as clinical data in extreme obesity is limited, and the risk of bleeding and thrombosis may be increased.
- Anti-Xa monitoring should be considered for patients >150kg or those with severe renal impairment, to ensure adequate anticoagulation and minimize the risk of bleeding.
- Dose adjustments may be necessary based on individual patient factors, such as renal function, liver function, and concomitant medications, to ensure optimal anticoagulation and minimize the risk of adverse events.
From the Research
Anticoagulation Strategies in Obesity
The optimal anticoagulation strategy in obesity is not well established, but several studies provide guidance on the use of different anticoagulants in this population.
- Low-molecular-weight heparin (LMWH) is commonly used for thromboprophylaxis in obese patients, with recommended doses including enoxaparin 40 mg twice daily, dalteparin 5,000 IE twice daily, or tinzaparin 75 IU/kg once daily for patients with BMI ≥ 40 kg/m2 2.
- For treatment with LMWH, a reduced weight-based dose of enoxaparin 0.8 mg/kg twice daily may be considered in patients with BMI ≥ 40 kg/m2, and no dose capping of dalteparin and tinzaparin should be applied for body weight < 140 kg 2.
- Non-vitamin K antagonist oral anticoagulants (NOACs) such as rivaroxaban, apixaban, or dabigatran may be used as thromboprophylaxis in patients with BMI < 40 kg/m2, and rivaroxaban and apixaban may be administered to obese patients with VTE or AF, including BMI > 40 kg/m2, at standard fixed-dose 2.
- Apixaban does not require dose adjustment in patients weighing above a certain threshold (e.g., ≥ 120 kg), and data suggest that obesity does not substantially influence the efficacy, effectiveness, or safety of apixaban in patients with NVAF or VTE 3.
Special Considerations
- In patients with morbid obesity (BMI ≥ 40 kg/m2 or weight ≥ 120 kg), the current evidence for anticoagulant therapy is insufficient, and a tailored approach with meticulous monitoring is necessary to achieve an optimal therapeutic balance 4.
- The use of DOACs in morbidly obese patients requires caution, particularly for those requiring anticoagulation for VTE treatment, until additional higher-quality data become available 5.
- Updated guidance recommendations on using DOACs in patients with obesity for treatment and prevention of VTE, as well as following bariatric surgery, have been provided by the ISTH SSC Subcommittee on Control of Anticoagulation 6.