Abstract Number: PB0347
Meeting: ISTH 2021 Congress
Background: Plasma rivaroxaban (RIVA) concentration cannot be evaluated through classic coagulation tests. AntiXa activity tests with specific calibrators, not widely available, are needed.
Aims: To correlate heparin calibrated (HC) antiXa activity (hybrid curve) obtained in 3 reactive/instrument systems with RIVA concentrations measured through antiXa test calibrated with specific calibrators. To compare antiXa-HC values calculated in the 3 systems for clinically relevant RIVA levels.
Methods: Multicenter study. Samples from center 1 were distributed in 2 others to measure antiXa-HC activity. Samples from 19 consecutive patients receiving RIVA at peak or through (8 -321 ng/mL), and 20 receiving enoxaparin (0.01-1.76 U/mL).
RIVA measurement: HemosIL Liquid antiXa(HEM) in ACLTOP, HemosIL Rivaroxaban Calibrators and Controls (IL, Instrumentation Laboratory).
AntiXa-HC Activity (hybrid curves)
1) HEM, HemosIL Heparin Calbrator in ACLTOP;
2) Innovance Heparin(INN), universal calibrators in Sysmex CS-2500 (Siemens Health Care);
3) STA-Liquid AntiXa(STA), HNF/HBPM calibrators in STA- COMPACT MAX (Diagnostica STAGO).
Statistics: SPSS 23 software.
Results: Statistically significant correlation between AntiXa-HC and RIVA concentrations were found, table 1.
| Table 1. Correlation and regression lines between anti Xa-HC assays and RIVA levels, and Anti Xa-HC in LMWH samples | ||||||
|---|---|---|---|---|---|---|
| Anti Xa-HC activity HEM vs RIVA (ng/mL) | Anti Xa-HC activity INN vs RIVA (ng/mL) | Anti XA-HC activity STA vs RIVA (ng/mL) | Bland Altman Anti Xa-HC U/mL HEM-INN |
Bland Altman Anti Xa-HC U/mL HEM-STA |
Bland Altman |
|
| R2 | 0,955 | 0,964 | 0.828 | – | – | – |
| Linear regression Slope (95%CI) (RIVA samples) | 0,008 (0,007 to 0,009) |
0,0086 (0,008 to 0,009) |
0.010 (0.007 to 0.0129 |
– | – | – |
| Linear regression Y intercept (95%CI) (RIVA Samples) |
-0,112 (-0,228 to 0,004) |
-0,081 (-0,193 to 0,031) |
0.348 (0.049 to 0.647) |
– | – | – |
| Bland Altman BIAS (95% CI) Anti Xa-HC U/mL RIVA samples |
– | – | – | -0.086 (-0.126 to -0.046) |
-0.630 (-0.854 to -0.406) |
-0.544 (-0.765 to -0.322) |
| Bland Altman BIAS (95% CI) Anti Xa-HC U/mL LMWH samples |
– | – | – | -0.041 (-0.097 to -0.014) |
-0.012 (-0.088 to 0.065) |
0.030 (-0.028 to 0.088) |
Table 1. Correlation and regression lines between anti Xa-HC assays and RIVA levels, and Anti Xa-HC in LMWH samples
Linear regression equations AntiXa-HC to RIVA were similar for HEM and INN, but different for STA (Higher Y intercept). In RIVA samples, AntiXa-HC comparison between systems by Bland Altman curves yielded significant and important BIAS (table 1) for STA-HEM and STA-INN. AntiXA-HC estimated by regression equations at three RIVA clincal relevant concentrations showed that values from STA are higher than HEM and INN(table 2).
| Table 2 Anti Xa-HC activity expected by linear regression equation at three different clinically relevant RIVA concentrations | |||
|---|---|---|---|
| RIVA concentration (ng/mL) |
Anti Xa-HC HEM (U/mL) value (95%CI) |
Anti Xa-HC INN (U/mL) value (95%CI) |
Anti XA-HC STA (U/mL) value (95%CI) |
| 30 | 0,13 (0,01-0,24) | 0,18 (0,06-0,26) | 0,64 (0,35-0,94) |
| 50 | 0,29 (0,17-0,40) | 0,35 (0,24-0,46) | 0,84 (0,55-1,15) |
| 200 | 1,49 (1,37-1,60) | 1,64 (1,52-1,75) | 2,35 (1,05-2,65) |
Table 2 Anti Xa-HC activity expected by linear regression equation at three different clinically relevant RIVA concentrations
In LMWH samples, Anti Xa-HC correlation R2 were 0.967,0.927 and 0.959,p<0.001 for HEM-INN, HEM-STA and INN-STA, respectively. Paired analysis did not demonstrate significant BIAS(table 1).
Conclusions: LMWH concentration measured by each reactive/instrument system are comparable using hybrid curves. However, in RIVA samples, each antiXa-HC system exert different results, close values with HEM and INN, but higher with STA. Knowledge of antiXa-HC values for RIVA levels with common reagent/instrument systems could be clinically usefull in laboratories that do not have specific calibrators available.
To cite this abstract in AMA style:
Martinuzzo M, Duboscq C, Arias M, López MS, S Viñuales E, Mezzarobba D, Privitera V, Penchasky D, Chuliber F, Ceresetto J, Gurfinkiel M, Barrera L. Plasmatic Rivaroxaban Concentration Estimation through the Measurement of Anti Xa Activity Calibrated with Heparin Calibrators Using 3 Reactive/Instrument Systems: Multicenter Study [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/plasmatic-rivaroxaban-concentration-estimation-through-the-measurement-of-anti-xa-activity-calibrated-with-heparin-calibrators-using-3-reactive-instrument-systems-multicenter-study/. Accessed September 24, 2023.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/plasmatic-rivaroxaban-concentration-estimation-through-the-measurement-of-anti-xa-activity-calibrated-with-heparin-calibrators-using-3-reactive-instrument-systems-multicenter-study/