Abstract Number: PB0557
Meeting: ISTH 2020 Congress
Background: We have showed that fibrinogen (FIB) prothrombin time derived method (FibPT-d), an easily available and economic method, is not useful when LMWH or rivaroxaban are present in the blood samples.
Aims: To compare FIB results obtained by Clauss method (FIB-C) and FibPT-d with two thromboplastins in anticoagulated patients with apixaban.
Population: 40 consecutive patients taking apixaban 5 mg twice a day (with normal PT and APTT before initiating anticoagulation) and 40 healthy controls (NC).
Methods: Fib C by HemosiL Fibrinogen C (FIBC) Fib PT-d with rabbit brain (HemosiL PT Fibrinogen HS plus, FibPT HS) and human recombinant (HemosiL Recombiplastin 2 G, FibPT RP). Apixaban levels by Liq Anti Xa with specific calibrators (HemosiL Apixaban calibrators). FIB assays were calibrated with Calibration Plasma and performed on ACL TOP platform.
Data Analysis: BIAS % between FibC and FIBPT-d with each thromboplastin were calculated. Comparison between methods was performed by Bland Altman plots.
Results: The table shows fibrinogen level by Clauss and the BIAS % between FIBC and Fib PT-d with each thromboplastin. Bland Altman analysis shows that there is a positive bias (p<0.001) for FibPT-d in either NC or anticoagulated samples. With FIB PT HS the bias was even bigger, in a concentration dependent manner, compared to NC. The results show a greater bias when rabbit brain compared to human recombinant thromboplastin was used.
Conclusions: Although the FibPT-d is an economic and rapid method, it should not be used in anticoagulated patients with apixaban because results could be overestimated. This behavior is like that previously shown by fibrinogen prothrombin time derived assay in plasmas containing rivaroxaban. As the origin of thromboplastin affects the results, these findings should not be extrapolated to other reagents / coagulometers systems.
|FIB-C g/L (mean and range)||% BIAS Fib PTHS||% BIAS Fib PTRP|
|Normal controls n=40||3.10 (2.03 – 5.10)||13 CI 95 %: 11.6-15.9||19.0 CI 95 %:17.1-20.8|
|Apixaban anticoagulated patients n=40 (10-571 ng/mL)||3.90 (2.78 – 7.25)||21.7 CI 95%:14.6-28.9 P<0.0001||15.7 CI 95: % 8.7-22.64 P<.0001|
[Table 1 Bias Fib PT-d vs Fib C in samples from patients anticoagulated with apixaban]
To cite this abstract in AMA style:Duboscq C, Martinuzzo M, Ceresetto J, Lopez M, Barrera L, Avila Rueda J, Oyhamburu J, Stemmelin G. Fibrinogen Prothrombin Time Derived Method Is Not Useful in Anticoagulated Patients with Apixaban [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/fibrinogen-prothrombin-time-derived-method-is-not-useful-in-anticoagulated-patients-with-apixaban/. Accessed December 10, 2023.
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