Key result
Chromogenic anti-Xa assays strongly correlate with UHPLC-MS/MS for rivaroxaban levels but systematically underestimate concentrations.
Why the study?
Monitoring anticoagulation levels of rivaroxaban in non-valvular atrial fibrillation is clinically valuable, prompting evaluation of plasma levels via chromogenic anti-Xa assays and UHPLC-MS/MS compared to expected ranges.
How do rivaroxaban levels measured by chromogenic anti-Xa assays and UHPLC-MS/MS compare with expected drug levels in Chinese patients with NVAF?
Observational (n=182)
No
How do rivaroxaban levels measured by chromogenic anti-Xa assays and UHPLC-MS/MS compare with expected drug levels in Chinese patients with NVAF?
Effect estimate: Pearson's r 0.987 (95% CI 0.978-0.990)
Rivaroxaban concentrations in Chinese patients with NVAF are highly variable and generally higher than expected ranges from clinical trials, regardless of the assay used.
Anti-Xa assays warrant cautious interpretation for rivaroxaban monitoring in Chinese NVAF; leaves open population-specific calibration and outcome validation.
Background: Monitoring the level of anticoagulation by rivaroxaban in patients with non-valvular atrial fibrillation (NVAF) is valuable in clinical practice. Our study aimed to measure the plasma levels of rivaroxaban both by chromogenic anti-Xa assays and ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) in Chinese patients with NVAF, and compare with the expected drug levels. Materials and methods: A prospective clinical study was conducted to include NVAF patients taking rivaroxaban. Rivaroxaban levels were determined using UHPLC-MS/MS and chromogenic anti-Xa assays (Biophen DiXal and Zhenyuan anti-Xa). The correlation and agreement among measurements by different assays were evaluated. The rivaroxaban levels in Chinese patients were also compared with the expected drug levels, which were estimated from previous clinical trials and widely accepted. Results: A total of 243 plasma samples were collected from 182 patients. Results measured using the two chromogenic anti-Xa assays were both linearly correlated with those measured using UHPLC-MS/MS, especially in the range of 50–200 ng/mL, but the concentrations determined using anti-Xa assays were systematically underestimated. Rivaroxaban levels measured by either UHPLC-MS/MS or chromogenic anti-Xa assays were both larger than the expected ranges. There was no difference in the distribution of concentration whether the patients took an appropriate dose or not. However, for Chinese patients with an inappropriate lower dose, trough concentrations were less likely to exceed the expected concentration ranges. Conclusion: Rivaroxaban concentration in patients with NVAF were highly variable compared to the expected ranges estimated from clinical trials, whether measured by UHPLC-MS/MS or chromogenic anti-Xa assays. Chinese patients taking an appropriate rivaroxaban dose are more likely to obtain a rivaroxaban concentration level higher than expected, independent on the assay used.
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Liu et al. (2022) conducted an observational in Non-valvular atrial fibrillation (NVAF) (n=182). Chromogenic anti-Xa assays (Biophen DiXal and Zhenyuan anti-Xa) vs. UHPLC-MS/MS was evaluated on Correlation between Biophen DiXal anti-Xa assay and UHPLC-MS/MS (Pearson's r 0.987, 95% CI 0.978-0.990). Chromogenic anti-Xa assays were highly correlated with UHPLC-MS/MS for measuring rivaroxaban levels (Pearson's r 0.987 for Biophen DiXal), although they systematically underestimated concentrations.
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