Key result
Routine aPTT and PT correlate strongly with DOAC concentrations, identifying subtherapeutic drug levels.
Why the study?
DOACs affect coagulation tests, and understanding these effects is important for therapeutic monitoring in patients with nonvalvular atrial fibrillation.
Do routine coagulation tests (aPTT and PT) correlate with drug levels in patients with nonvalvular atrial fibrillation taking dabigatran or rivaroxaban?
Cross-Sectional (n=130)
No
Do routine coagulation tests (aPTT and PT) correlate with drug levels in patients with nonvalvular atrial fibrillation taking dabigatran or rivaroxaban?
Effect estimate: R2 = 0.74 for dabigatran/aPTT; R2 = 0.69 for rivaroxaban/PT
p-value: p=<0.0001
Routine coagulation tests such as aPTT and PT show good correlation with specific DOAC assays and may be useful for identifying out-of-therapeutic-range concentrations of dabigatran and rivaroxaban.
Dabigatran and rivaroxaban, direct oral anticoagulants (DOACs), affect coagulation tests, and knowledge of their effects is important for therapeutic monitoring. Our aim was to examine the association between DOAC levels and routine coagulation tests in patients with nonvalvular atrial fibrillation. Samples from patients receiving dabigatran (150 mg) and patients receiving rivaroxaban (20 mg) were collected 2 hours after drug intake. Direct oral anticoagulant concentrations were determined using direct Hemoclot thrombin inhibitor (HTI) assay (HTI test) and a direct Xa inhibitor (Anti Xa-Riva). The routine coagulation measured included activated partial thromboplastin time (aPTT) and prothrombin time (PT). The median plasmatic dabigatran was 128.3 ng/mL (95% confidence interval [CI]: 93.7-222.6 ng/mL). The HTI exhibited a good correlation with aPTT ( R 2 = 0.74; P < .0001). The median plasmatic rivaroxaban was 223.9 ng/mL (95% CI: 212.3-238.9 ng/mL). Anti-Xa-Riva correlated with PT ( R 2 = 0.69, P< .0001) and aPTT (R 2 = 0.36, P < .001), but prolonged PT results were obtained, even below the rivaroxaban therapeutic range (20%). The routine coagulation tests were able to identify out of therapeutic range concentrations for dabigatran and rivaroxaban. We suggest the use of these screening tests to better understand and monitor the subtherapeutic concentrations of these DOACs.
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Silva et al. (2019) conducted a cross-sectional in Nonvalvular Atrial Fibrillation (n=130). Dabigatran and Rivaroxaban was evaluated on Correlation of direct oral anticoagulant plasma levels (HTI test for dabigatran, Anti-Xa for rivaroxaban) with routine screening coagulation tests (aPTT and PT) (R2 = 0.74 for dabigatran/aPTT; R2 = 0.69 for rivaroxaban/PT, p=<0.0001). Dabigatran and rivaroxaban plasma concentrations showed significant correlations with routine coagulation tests (aPTT R²=0.74 for dabigatran, PT R²=0.69 for rivaroxaban), enabling the identification of subtherapeutic drug levels.
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