How do you measure the oral anti-Xa anticoagulants rivaroxaban, apixaban, edoxaban, and betrixaban?

Primary tabs

Prothrombin time (PT)
4% (4 votes)
Activated partial thromboplastin time (APTT, PTT)
3% (3 votes)
Chromogenic anti-Xa assay with specific calibrators
51% (47 votes)
We don't measure the anti-Xa anticoagulants
42% (39 votes)
Total votes: 93