Summary
The Belgian national External Quality Assessment Scheme performed a nationwide survey
using lyophilised plasma samples spiked with dabigatran or rivaroxaban to demonstrate
to the Belgian clinical laboratories how these drugs affect their routine coagulation
assays prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen
and antithrombin. Virtually all Belgian laboratories performing routine coagulation
testing (189/192) participated in the survey. Both, dabigatran and rivaroxaban significantly
prolonged the PT and aPTT in a concentration- and reagent-dependent manner. PT reagents
were more influenced by rivaroxaban than by dabigatran and aPTT reagents more influenced
by dabigatran than by rivaroxaban. Among PT reagents, Neoplastin R® was the most sensitive
to rivaroxaban and Innovin ® and Thromborel S® the least sensitive. Converting PT
results to INR only increased the variability between reagents. Among aPTT reagents,
Actin FSL® was the least sensitive to dabigatran while the other aPTT reagents showed
slightly higher sensitivities. The presence of dabigatran led to falsely reduced fibrinogen
concentrations when measured with a low thrombin concentration reagent. The presence
of dabigatran caused an overestimation of the antithrombin level when measured with
a thrombin-based activity assay and the presence of rivaroxaban an overestimation
of the antithrombin level when measured with a FXa-based assay. Instrument-related
differences were found for all tested parameters. In conclusion, this paper provides
detailed information on the effect of dabigatran and rivaroxaban on routine coagulation
assays as performed with a large number of reagent/instrument combinations.
Keywords
Dabigatran - external quality assessment - rivaroxaban - routine coagulation assays