Biophen DiXaI LOW and STA LAX assays correlated well with LC-MS/MS in patients not bridged with LMWH (R up to 0.97), but performance decreased significantly when residual LMWH activity was present.
Observational
Do STA LAX and Biophen DiXaI assays accurately estimate rivaroxaban plasma concentrations compared to LC-MS/MS in perioperative patients with or without LMWH bridging?
Anti-Xa assays accurately estimate low rivaroxaban concentrations in unbridged patients but are inaccurate and should not be used for procedural safety assessment in patients bridged with LMWH.
Effect estimate: R: 0.97, 0.96, and 0.91 (without LMWH); R: 0.18 and 0.19 (with LMWH)
INTRODUCTION: Estimation of residual rivaroxaban plasma concentrations may be requested before invasive procedures and some patients at high thromboembolic risk will have a bridging therapy with heparins when rivaroxaban is interrupted. OBJECTIVE: The objective of this study was to assess the performance of the STA-Liquid Anti-Xa assay (STA LAX) and the low and normal procedures of the Biophen Direct Factor Xa Inhibitors (DiXaI) assay, in patients with and without bridging with low-molecular-weight heparins (LMWHs). MATERIALS AND METHODS: or before an invasive procedure. Rivaroxaban plasma concentrations were estimated using Biophen DiXaI, Biophen DiXaI LOW, and STA LAX and compared to liquid chromatography coupled with mass spectrometry (LC-MS/MS) measurements. Stratifications were performed according to heparin bridging. RESULTS: The Biophen DiXaI LOW and STA LAX showed better correlation with LC-MS/MS measurements than Biophen DiXaI in patients not bridged with LMWH (R: 0.97, 0.96, and 0.91, respectively). However, the performance of Biophen DiXaI LOW and STA LAX decreased when residual LMWH activity was present (R: 0.18 and 0.19 respectively) demonstrating that these tests are not specific to rivaroxaban. CONCLUSION: In patients not bridged with LMWH, we suggest to use the Biophen DiXaI LOW and STA LAX for the estimation of rivaroxaban concentrations <50 ng/mL. These results should be confirmed on a larger cohort of patients. Patients bridged with LMWH have inaccurate estimates of low levels of rivaroxaban and the 3 assays studied should not be used to estimate if it is safe to perform a procedure.
Lessire et al. (2016) conducted an observational in Patients taking rivaroxaban requiring invasive procedures. STA-Liquid Anti-Xa assay and Biophen Direct Factor Xa Inhibitors assay vs. Liquid chromatography coupled with mass spectrometry (LC-MS/MS) was evaluated on Correlation of estimated rivaroxaban plasma concentrations with LC-MS/MS measurements (R: 0.97, 0.96, and 0.91 (without LMWH); R: 0.18 and 0.19 (with LMWH)). Biophen DiXaI LOW and STA LAX assays correlated well with LC-MS/MS in patients not bridged with LMWH (R up to 0.97), but performance decreased significantly when residual LMWH activity was present.