Abstract Number: PB2475
Meeting: ISTH 2020 Congress
Background: Apixaban, unlike Vitamin-K antagonists, has a predictable effect and does not require biological control routinely. However, estimation of plasmatic concentration could be useful in individual dose adjustment, certain clinical circumstances and selected patients.
1) Evaluate biological effect of apixaban with chromogenic anti-Xa test with calibrators for apixaban and heparin
2) Analyze correlation between both techniques.
3) Study application of a correction factor to estimate plasmatic concentration of apixaban based on anti-Xa activity.
Methods: 100 patients anticoagulated with apixaban were included (1Jan2018 2018-31Dec2018). Anti Xa activity (HemosIL Liquid anti-Xa) and a chromogenic assay to estimate apixaban concentration with specific calibrator (TECHNOVIEW apixaban Cal High Set) in the ACL TOP coagulometer (Instrumentation Laboratory, MA, USA), were determined. Pearson´s coefficient was calculated to assess the correlation between both techniques. A linear regression was performed to calculate the estimated levels of apixaban based on anti-Xa activity. P< 0.05 were considered significant.
The results were validated in a prospective cohort of patients anticoagulated with apixaban (n=35) (1Jan2019-30Apr2019). Estimated apixaban levels (linear regression) and apixaban levels obtained with specific calibrator were compared. Statistical analysis was performed with SPSS version 19.0 for Windows (SPSS, Chicago, IL, USA).
Results: An excellent correlation was observed between the anti-Xa activity and the estimated levels of apixaban (Pearson´s test: r=0.930, p< 0.001). Using linear regression (y=140.54x + 1.3356) we estimated apixaban levels and compared them with those obtained with a specific calibrator. The median difference was 8.9 ng/ml. Figure 1.
Conclusions: Plasmatic concentration of apixaban can be estimated by applying a correction factor to the anti-Xa activity (calibrated for heparins). Anti Xa chromogenic assay with specific calibrators for apixaban is a quantitative method and easy to perform, allowing to determine estimated plasma concentration. This approach would reduce the cost of reagents, although a different correction factor needs to be calculated in each laboratory.
To cite this abstract in AMA style:Velasco D, Vidal R, Garcia Raso A, Martin S, Llamas P. Correlation between Anti-Xa Activity and Plasmatic Levels of Apixaban [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/correlation-between-anti-xa-activity-and-plasmatic-levels-of-apixaban/. Accessed January 23, 2022.
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