From the Guidelines
For a patient with a history of DVT on warfarin with an INR of 2.0, the current warfarin dose should be continued as the patient is within the recommended therapeutic INR range of 2.0 to 3.0. The american society of hematology 2020 guidelines for management of venous thromboembolism support the use of an international normalized ratio (INR) range of 2.0 to 3.0 for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention 1. Key aspects of management include:
- Maintaining the current warfarin dose of 7.5 mg on Sunday, Monday, and Fridays, and 10 mg on Tuesday and Saturday
- Regular INR monitoring, typically every 1-2 weeks until stable, then monthly
- Investigating potential causes for any fluctuations in INR, such as missed doses, dietary changes with increased vitamin K intake, or medication interactions
- Patient education on the importance of medication adherence, consistent vitamin K intake in diet, and reporting any bleeding symptoms
- Consideration of adjusting the target INR range or adding an antiplatelet agent if the patient has recurrent thrombosis risk factors or has experienced a recurrent DVT at this INR level, after specialist consultation. The current INR of 2.0 indicates that warfarin is providing adequate anticoagulation for this patient, as it reflects a reduction in vitamin K-dependent clotting factors to approximately 20-30% of normal activity, which is sufficient for most DVT patients 1.
From the FDA Drug Label
The dose of warfarin should be adjusted to maintain a target INR of 2.5 (INR range, 2.0 to 3.0) for all treatment durations. For patients with two or more episodes of documented DVT or PE, indefinite treatment with warfarin is suggested
The patient's current INR is 2.0, which is within the recommended range of 2.0 to 3.0. However, the target INR is 2.5.
- The patient's warfarin dose may need to be adjusted to achieve the target INR of 2.5.
- The patient should be monitored closely to ensure that their INR remains within the therapeutic range.
- The patient's warfarin dose should be adjusted based on their PT/INR response to the drug.
- It is recommended that the patient's INR be checked regularly to ensure that it remains within the therapeutic range 2.
From the Research
Patient Management
The patient's INR is 2.0, which is within the therapeutic range of 2.0-3.0 for patients with a history of Deep Vein Thrombosis (DVT) 3.
Warfarin Dosage
The patient is currently taking warfarin 7.5 mg on Sunday, Monday, and Fridays, and 10 mg on Tuesday and Saturday. This dosage regimen is not explicitly addressed in the provided studies, but the INR of 2.0 suggests that the current dosage is effective in achieving the desired level of anticoagulation.
Monitoring and Adjustment
It is essential to continue monitoring the patient's INR regularly to ensure that it remains within the therapeutic range. According to 4, the INR is only valid for patients on well-controlled anticoagulant therapy, where the level of anticoagulation is reasonably stable over a moderate length of time.
Key Considerations
- The patient's age and other risk factors should be considered when determining the target INR range. For example, patients over 62 years old may require a lower target INR range of 2.0-2.5 to minimize the risk of major bleeding 5.
- The risk of bleeding increases exponentially with INR, and becomes clinically unacceptable once the INR exceeds 5.0 3.
- The patient should be educated on the importance of adhering to their warfarin regimen and attending regular INR check-ups to minimize the risk of thromboembolic events and bleeding complications.
Recommendations
- Continue to monitor the patient's INR regularly to ensure that it remains within the therapeutic range of 2.0-3.0.
- Consider the patient's age and other risk factors when determining the target INR range.
- Educate the patient on the importance of adhering to their warfarin regimen and attending regular INR check-ups.