title: Effect of standardization and normalization on imprecision of calibrated automated thrombography: an international multicentre study.
abstract: Calibrated automated thrombography (CAT) enables continuous measurement of thrombin generation (TG). Initial clinical studies using the CAT method showed large variability of normal values, indicating the necessity for a standardized CAT protocol. This international study assessed the intra- and inter-assay imprecision of CAT as well as the inter-centre variability of results in five European centres using locally available reagents and conditions (study 1) and a standardized protocol in which results were normalized (study 2). Samples with and without corn trypsin inhibitor from six healthy volunteers, two haemophilia patients and one protein C deficient patient were assayed. Study 1 confirmed that the use of different sources and concentrations of tissue factor (TF) and different phospholipid (PL) mixtures produced large variability in results. The second study demonstrated that, using the same source and concentration of TF, PL and the same test procedure, this variability could be significantly reduced. Normalization of results improved the inter-centre variability. The benefit of contact factor inhibition prior to TG measurement was confirmed. These results demonstrated that standardization of CAT reduces the variability of results to acceptable limits. Standardization and normalization should be considered in future clinical studies which apply TG testing to clinical decision making.
authors: Department of Haematology, Addenbrooke's NHS Trust, Cambridge, UK.
authors: Yesim
authors: Y
authors: Dargaud
authors: Rodger
authors: R
authors: Luddington
authors: Elaine
authors: E
authors: Gray
authors: Claude
authors: C
authors: Negrier
authors: Thomas
authors: T
authors: Lecompte
authors: Sirak
authors: S
authors: Petros
authors: John
authors: J
authors: Hogwood
authors: Jean-Claude
authors: JC
authors: Bordet
authors: Veronique
authors: V
authors: Regnault
authors: Annelie
authors: A
authors: Siegemund
authors: Trevor
authors: T
authors: Baglin
mesh_terms: D000328:Adult; D001780:Blood Coagulation Tests / Q000592:standards*; D002138:Calibration; D001330:Electronic Data Processing; D005260:Female; D006467:Hemophilia A / Q000097:blood; D002836:Hemophilia B / Q000097:blood; D006487:Hemostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D020151:Protein C Deficiency / Q000097:blood; D013917:Thrombin / Q000096:biosynthesis*
chemical_list: D013917:Thrombin