What is the target International Normalized Ratio (INR) in patients with Antiphospholipid Syndrome (APS)?

From the Guidelines

The target INR for patients with antiphospholipid syndrome should be between 2 and 3 to effectively balance the risk of excessive bleeding against the risk of thrombosis. This recommendation is based on the 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack from the American Heart Association/American Stroke Association 1. The guideline suggests that in patients with ischemic stroke or TIA with confirmed antiphospholipid syndrome treated with warfarin, a target INR between 2 and 3 is reasonable 1.

Some key points to consider in the management of antiphospholipid syndrome include:

• Antiplatelet therapy alone is recommended for patients with isolated antiphospholipid antibody but do not fulfill the criteria for antiphospholipid syndrome 1
• Warfarin is recommended for patients with ischemic stroke or TIA who meet the criteria for antiphospholipid syndrome to reduce the risk of recurrent stroke or TIA 1
• Rivaroxaban is not recommended for patients with antiphospholipid syndrome with history of thrombosis and triple-positive antiphospholipid antibodies due to excess thrombotic events compared with warfarin 1

It is essential to monitor INR levels regularly and educate patients about potential drug and food interactions that can affect warfarin's efficacy. The choice of target INR range should be individualized based on the patient's risk of thrombosis and bleeding.

From the Research

Target INR in Antiphospholipid Syndrome

• The target INR range for patients with antiphospholipid syndrome (APS) is a topic of debate, but most studies suggest a range of 2.0 to 3.0 2, 3, 4.
• A study published in 2012 recommends warfarin to an INR range of 2.0 to 3.0 for patients with a first venous thromboembolic event 2.
• Higher anticoagulation intensity is recommended for patients presenting with arterial events 2.
• The optimal intensity of warfarin therapy is an ongoing issue, but most clinicians currently favor a target INR in the 2.0 to 3.0 range 3.
• A study published in 2022 found that the CoaguChek XS point-of-care device showed higher INR values than venous laboratory INR, with an increased average of 0.42 ± 0.54 5.
• The study also found that the INR >4 group presented a lower correlation between CoaguChek XS and venous laboratory INR compared to the other ranges 5.

Factors Influencing INR Target Range

• The presence of antiphospholipid antibodies may interfere with determination of the INR, requiring other approaches to monitor and adjust the warfarin dose 6, 3.
• The aPL profile did not influence the results of the CoaguChek XS point-of-care device 5.
• The type of thrombotic event (venous or arterial) may influence the target INR range, with higher intensity anticoagulation recommended for arterial events 2.

Clinical Implications

• Long-term anticoagulation is considered the standard treatment for patients with APS, with a target INR range of 2.0 to 3.0 2, 3, 4.
• The choice of anticoagulant therapy and target INR range should be individualized based on the patient's risk factors and clinical presentation 2, 6.
• Point-of-care devices, such as the CoaguChek XS, may not be suitable for routine use in APS patients due to the potential for inaccurate INR results 5.