The objective of the study is to demonstrate the performances of the STA® - Rivaroxaban Calibrator and STA® - Rivaroxaban Control in combination with the STA® - Liquid Anti-Xa to determine the quantity of rivaroxaban in plasma samples by measurement of its direct anti-Xa activity.

The study is a method comparison between a reference method (LCMS) and the candidate device.

Between 90 and 120 samples obtained from patients treated by rivaroxaban will be collected on 3 sites in the US according to the inclusion and exclusion criteria detailed in the protocol. These samples will be frozen after the collection and sent to the hemostasis laboratories for testing and to a LCMS central laboratory validated for rivaroxaban measurement.

Results expressed in ng/mL obtained with STA® - Liquid Anti-Xa, used in combination with STA® - Rivaroxaban Calibrator and STA® - Rivaroxaban Control will be compared to the result obtained by the LCMS laboratory.

Diagnostica Stago will analyse the results thanks to regressions according to CLSI EP9-A3 recommendations (guideline dedicated to method comparison for quantitative assay) in order to support the equivalence between the 2 methods.

Inclusion Criteria:

Between 30 and 40 samples/site obtained from patients treated with rivaroxaban.(ideally 10-15 samples per indication and per site depending on the site practices):

• Prophylaxis of VTE in patients undergoing knee or hip replacement surgery (10 mg OD): orthopaedic department of the hospital will be in charge of the sample collection.
• Treatment of deep vein thrombosis (DVT), pulmonary embolism (PE), and risk reduction of DVT and PE recurrence; (15 mg BID for 3 weeks then 20 mg OD): different departments of the hospital will be in charge of the sample collection (samples can come e.g., from emergency room, vascular lab or cancer unit).
• Stroke prevention and reduction of systemic embolism in non-valvular patients with atrial fibrillation (SPAF) (20 mg OD): cardiology department of the hospital will be in charge of the sample collection.

Exclusion Criteria:

• Patients less than 18 years old
• Patients under other anti-coagulant treatment
• Samples that are not collected, stored, or handled in accordance with sample collection procedures defined in CLSI H21-A5

Patients receiving rivaroxaban treatment for one of the 3 drug indications cleared in the US