title: Interference of the new oral anticoagulant dabigatran with frequently used coagulation tests.
abstract: 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.
authors.affiliation: Institute of Laboratory Medicine, Municipal Hospital Hietzing-Rosenhuegel, Vienna, Austria. michael@halbmayer.at
authors.forename: Walter-Michael
authors.initials: WM
authors.lastname: Halbmayer
authors.forename: Guenter
authors.initials: G
authors.lastname: Weigel
authors.forename: Peter
authors.initials: P
authors.lastname: Quehenberger
authors.forename: Josef
authors.initials: J
authors.lastname: Tomasits
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Haushofer
authors.forename: Gerold
authors.initials: G
authors.lastname: Aspoeck
authors.forename: Lorin
authors.initials: L
authors.lastname: Loacker
authors.forename: Mirjam
authors.initials: M
authors.lastname: Schnapka-Koepf
authors.forename: Georg
authors.initials: G
authors.lastname: Goebel
authors.forename: Andrea
authors.initials: A
authors.lastname: Griesmacher
mesh_terms: D000925:Anticoagulants / Q000737:chemistry* / Q000627:therapeutic use; D001562:Benzimidazoles / Q000737:chemistry* / Q000627:therapeutic use; D001780:Blood Coagulation Tests; D003124:Colorimetry; D000069604:Dabigatran; D005176:Factor XIII / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D010314:Partial Thromboplastin Time; D011516:Prothrombin / Q000737:chemistry / Q000378:metabolism; D011517:Prothrombin Time; D011725:Pyridines / Q000737:chemistry* / Q000627:therapeutic use; D020521:Stroke / Q000517:prevention & control; D054556:Venous Thromboembolism / Q000188:drug therapy
chemical_list: D000925:Anticoagulants; D001562:Benzimidazoles; D011725:Pyridines; D011516:Prothrombin; C025337:Factor IIa; D005176:Factor XIII; D000069604:Dabigatran