LMWH-calibrated anti-FXa assays showed good agreement with drug-specific assays (κ = 0.76 for rivaroxaban, κ = 0.82 for apixaban) and can reliably exclude clinically relevant concentrations of these drugs.
Cross-Sectional (n=61)
No
Can a commercial LMWH-calibrated anti-FXa assay be used to exclude the presence of clinically relevant concentrations of rivaroxaban and apixaban in patients with non-valvular atrial fibrillation?
LMWH-calibrated anti-FXa assays can be used in emergency settings to reliably rule out clinically relevant concentrations of rivaroxaban and apixaban, though they are not suitable for precise quantitative determination.
Estimación del efecto: κ = 0.76 (95% CI 0.56-0.96)
INTRODUCTION: Clinical application of rivaroxaban and apixaban does not require therapeutic monitoring. Commercial anti-activated factor X (anti-FXa) inhibition methods for all anti-FXa drugs are based on the same principle, so there are attempts to evaluate potential clinical application of heparin-calibrated anti-FXa assay as an alternative method for direct FXa inhibitors. We aimed to evaluate relationship between anti-FXa methods calibrated with low molecular weight heparin (LMWH) and with drug specific calibrators, and to determine whether commercial LMWH anti-FXa assay can be used to exclude the presence of clinically relevant concentrations of rivaroxaban and apixaban. MATERIALS AND METHODS: Low molecular weight heparin calibrated reagent (Siemens Healthineers, Marburg, Germany) was used for anti-FXa activity measurement. Innovance heparin (Siemens Healthineers, Marburg, Germany) calibrated with rivaroxaban and apixaban calibrators (Hyphen BioMed, Neuville-sur-Oise, France) was used for quantitative determination of FXa inhibitors. RESULTS: Analysis showed good agreement between LMWH calibrated and rivaroxaban calibrated activity (κ = 0.76) and very good agreement with apixaban calibrated anti-Xa activity (κ = 0.82), respectively. Low molecular weight heparin anti-FXa activity cut-off values of 0.05 IU/mL and 0.1 IU/mL are suitable for excluding the presence of clinically relevant concentrations (< 30 ng/mL) of rivaroxaban and apixaban, respectively. Concentrations above 300 ng/mL exceeded upper measurement range for LMWH anti-FXa assay and cannot be determined by this method. CONCLUSION: Low molecular weight heparin anti-FXa assay can be used in emergency clinical conditions for ruling out the presence of clinically relevant concentrations of rivaroxaban and apixaban. However, use of LMWH anti-FXa assay is not appropriate for their quantitative determination as an interchangeable method.
Margetić et al. (Fri,) conducted a cross-sectional in Non-valvular atrial fibrillation (n=61). LMWH-calibrated anti-FXa assay vs. Drug-specific calibrated anti-FXa assay was evaluated on Agreement between LMWH calibrated and rivaroxaban calibrated anti-FXa activities (κ = 0.76, 95% CI 0.56-0.96). LMWH-calibrated anti-FXa assays showed good agreement with drug-specific assays (κ = 0.76 for rivaroxaban, κ = 0.82 for apixaban) and can reliably exclude clinically relevant concentrations of these drugs.