From the Guidelines
An INR of 1.81 is slightly below the typical therapeutic range of 2.0-3.0 for patients on anticoagulant therapy like warfarin, and may require a dosage adjustment to minimize the risk of thromboembolism and bleeding complications, as recommended by the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1. The target INR range may vary depending on the patient's condition, such as mechanical heart valves, which require a higher target INR of at least 2.5, as stated in the 2013 ACCF/AHA/ESC guidelines for the management of patients with atrial fibrillation 1.
- For patients with atrial fibrillation, the selection of antithrombotic therapy should be based on the absolute risks of stroke and bleeding, and the relative risk and benefit for a given patient, as recommended by the 2013 ACCF/AHA/ESC guidelines 1.
- The CHA2DS2-VASc score is recommended to assess stroke risk in patients with atrial fibrillation, and anticoagulation therapy is recommended for patients with a score of 2 or higher, as stated in the 2014 AHA/ACC/HRS guideline 1.
- INR should be determined at least weekly during initiation of therapy and monthly when anticoagulation is stable, as recommended by the 2014 AHA/ACC/HRS guideline 1. It is essential to discuss the INR result with a healthcare provider to determine the best course of action, as they will interpret the result in the context of the patient's specific medical condition and medication regimen, and adjust the medication dosage accordingly, to minimize morbidity, mortality, and improve quality of life.
From the FDA Drug Label
A moderate dose regimen (INR 2.0 to 3.0) is recommended for these patients. An INR of greater than 4. 0 appears to provide no additional therapeutic benefit in most patients and is associated with a higher risk of bleeding. 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.
The INR of 1.81 is below the recommended therapeutic range of 2.0 to 3.0. This means that the patient's blood is not thin enough, and they may be at risk of thrombosis. The patient's warfarin dose may need to be increased to achieve a therapeutic INR. 2 2 2
From the Research
Understanding INR of 1.81
- An INR (International Normalized Ratio) of 1.81 is below the typical therapeutic range for patients on warfarin, which is usually between 2.0 and 3.0 3.
- This value indicates that the patient's blood is not as thin as intended, which may increase the risk of thromboembolic events.
- According to a study, the risk of ischemic stroke is greatly reduced when INR exceeds 2, while the risk of intracranial hemorrhage increases monotonically as INR increases 3.
Comparison with Therapeutic Range
- The therapeutic range for warfarin is typically between 2.0 and 3.0, with an INR of 1.81 being below this range 4, 3.
- An INR between 2 and 2.5 is considered optimal for balancing the risk of ischemic stroke and intracranial hemorrhage 3.
- Patients with an INR below 2 may be at increased risk of thromboembolic events, while those with an INR above 3 may be at increased risk of bleeding complications.
Clinical Implications
- The clinical implications of an INR of 1.81 depend on the individual patient's condition and the reason for anticoagulation therapy.
- Patients with atrial fibrillation or mechanical heart valves may require more frequent INR monitoring to ensure that their INR remains within the therapeutic range 5.
- Healthcare providers may need to adjust the patient's warfarin dose to achieve an INR within the therapeutic range and minimize the risk of adverse events 6, 3.