Do patients on Eliquis (apixaban) require International Normalized Ratio (INR) checks to monitor anticoagulation?

From the Guidelines

No, patients on Eliquis (apixaban) do not require International Normalized Ratio (INR) checks to monitor anticoagulation. Unlike warfarin (Coumadin), which needs regular INR monitoring to ensure therapeutic anticoagulation levels, Eliquis is a direct oral anticoagulant (DOAC) that has predictable pharmacokinetics and a consistent dose-response relationship. According to the 2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1, NOACs (dabigatran, rivaroxaban, apixaban, and edoxaban) are recommended over warfarin in NOAC-eligible patients with AF, except with moderate-to-severe mitral stenosis or a mechanical heart valve. The guideline also recommends that renal function and hepatic function should be evaluated before initiation of a NOAC and should be reevaluated at least annually 1. Eliquis is typically prescribed at a standard dose of 5 mg twice daily for most patients, with a reduced dose of 2.5 mg twice daily for patients who meet certain criteria (age ≥80 years, body weight ≤60 kg, or serum creatinine ≥1.5 mg/dL). While routine coagulation monitoring is not required, patients on Eliquis should still have regular follow-up appointments to assess for bleeding complications, medication adherence, and kidney function, as renal impairment can affect drug clearance. The lack of monitoring requirement is one of the advantages of Eliquis over warfarin, making it more convenient for patients while maintaining effective anticoagulation.

Some key points to consider when prescribing Eliquis include:

• Evaluating renal function and hepatic function before initiation and at least annually 1
• Assessing for bleeding complications and medication adherence during follow-up appointments
• Adjusting the dose of Eliquis based on patient-specific criteria, such as age, body weight, and serum creatinine level
• Considering the advantages of Eliquis over warfarin, including the lack of monitoring requirement and predictable pharmacokinetics.

It's also important to note that the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1 recommends that the selection of antithrombotic therapy should be based on the risk of thromboembolism, irrespective of whether the AF pattern is paroxysmal, persistent, or permanent. However, the 2019 focused update 1 provides more recent and higher-quality evidence, which should be prioritized when making clinical decisions.

From the FDA Drug Label

When PCCs are used, monitoring for the anticoagulation effect of apixaban using a clotting test (PT, INR, or aPTT) or anti-factor Xa (FXa) activity is not useful and is not recommended.

INR monitoring is not required for patients on Eliquis (apixaban) as the drug's anticoagulation effect is not typically monitored using INR checks. Instead, anti-factor Xa (FXa) activity may be used to assess the anticoagulant effect of apixaban. 2

From the Research

INR Monitoring for Patients on Eliquis (Apixaban)

• Patients on Eliquis (apixaban) do not require routine International Normalized Ratio (INR) checks to monitor anticoagulation, as apixaban has predictable pharmacological properties 3, 4.
• However, studies have shown that apixaban can cause an increase in INR levels, with one study finding that 84.5% of patients had an elevated INR on day 1 of therapy 5.
• The clinical significance of this increase is not clear, but it is essential for clinicians to understand the association between apixaban and INR to avoid misinterpretation of routine coagulation assays 5.
• In certain situations, such as transitioning from apixaban to warfarin, monitoring apixaban anti-Xa levels can be useful in assessing the level of anticoagulation and avoiding unnecessary parenteral anticoagulation 6.
• Apixaban anti-Xa levels can be measured using chromogenic anti-Xa assays, which have been shown to be effective in evaluating the effectiveness of apixaban in patients with venous thrombo-embolism and atrial fibrillation 7.

Key Findings

• Apixaban does not require routine INR monitoring 3, 4.
• Apixaban can cause an increase in INR levels 5.
• Monitoring apixaban anti-Xa levels can be useful in certain situations, such as transitioning from apixaban to warfarin 6.
• Apixaban anti-Xa levels can be measured using chromogenic anti-Xa assays 7.

Clinical Implications

• Clinicians should be aware of the potential increase in INR levels in patients taking apixaban 5.
• Apixaban anti-Xa levels can be used to guide transitions from apixaban to warfarin, especially in patients with renal dysfunction 6.
• Further studies are needed to fully understand the clinical significance of the increase in INR levels caused by apixaban 5.