BACKGROUND: Dabigatran etexilate is a new oral anticoagulant for the therapy and 
prophylaxis of venous thromboembolism and stroke prevention in patients with 
atrial fibrillation. To investigate the extent of interactions of this new 
anticoagulant with frequently used coagulation assays, we completed a 
multicenter in vitro trial with Conformité Européenne(CE)-labeled 
dabigatran-spiked plasma samples.
METHODS: Lyophilized plasma samples with dabigatran concentrations ranging from 
0.00 to 0.48 μg/mL were sent to the coagulation laboratories of six major 
Austrian hospitals for evaluation. Coagulation assays were performed under 
routine conditions using standard reagents and analyzer.
RESULTS: Dabigatran led to a dose-dependent prolongation of the clotting times 
in coagulometric tests and influenced the majority of the parameters measured. 
Statistically significant interference could be observed with the prothrombin 
time (PT), activated partial thromboplastin time (aPTT) and PT/aPTT-based assays 
(extrinsic/intrinsic factors, APC-resistance test) as well as lupus 
anticoagulant testing. Even non-clotting tests, such as the colorimetric factor 
XIII activity assay and to a minor extent the amidolytic antithrombin activity 
assay (via factor IIa) were affected.
CONCLUSIONS: This multicenter trial confirms and also adds to existing data, 
demonstrating that laboratories should expect to observe strong interferences of 
coagulation tests with increasing concentrations of dabigatran. This finding 
might become particularly important in the elderly and in patients with renal 
impairment as well as patients whose blood is drawn at peak levels of 
dabigatran.