Table 2.
Advantages and drawbacks of coagulation tests that could be used to estimate plasma concentrations of NOACs or to estimate the relative intensity of anticoagulation.
| Molecule(s) | Utility | Laboratory experience | Availability | Sensitivity†/ specificity |
Dependence of the reagent | Cut-off for a risk of bleeding (unit(s) of expression) |
|
|---|---|---|---|---|---|---|---|
| aPTT | Dabigatran | Limited: poorly reflects the intensity of anticoagulation |
Not required | 24/7—all laboratories | ±100 ng/mL/no | Yes | Yes: depends on the indication and the reagent (ratio and seconds) |
|
| |||||||
| TT | Dabigatran | Limited: only to exclude the presence of dabigatran. Useful in the perioperative setting |
Not required | 24/7—all laboratories | Too sensitive‡/no | Yes | Not established |
|
| |||||||
| dTT | Dabigatran | Proven: accurately estimates the plasma concentrations—results expressed in ng/mL |
Required: requirement of calibrators and controls |
Requirement of trained personnel—only in specialized laboratories | ±10 ng/mL/no | No | Yes: depends on the indication (ng/mL) |
|
| |||||||
| ECT | Dabigatran | Limited: standardisation and validation required |
Required: interlot variability probably requiring calibrators and controls |
Requirement of trained personnel—only in specialized laboratories | ±15 ng/mL/no | Probably not but an interlot variability has been reported | Yes: depends on the indication (ratio and seconds) |
|
| |||||||
| ECA | Dabigatran | Proven: accurately estimates the plasma concentrations—results expressed in ng/mL |
Required: requirement of calibrators and controls |
Requirement of trained personnel—only in specialized laboratories | ±10 ng/mL/no | No | Yes: depends on the indication (ng/mL) |
|
| |||||||
| PT | Rivaroxaban | Limited: poorly reflects the intensity of anticoagulation |
Not required | 24/7—all laboratories | from ±100 to >500 ng/mL (depending on the reagent)/no | Yes | Not established |
|
| |||||||
| Chromogenic anti-Xa assays | Rivaroxaban/ Apixaban |
Proven: accurately estimates the plasma concentrations—results expressed in ng/mL |
Required: requirement of calibrators and controls |
Requirement of trained personnel—only in specialized laboratories | ±10 ng/mL/yes-no (depending on the anti-Xa assay) | No | Not established |
|
| |||||||
| DRVV-T | Dabigatran/ Rivaroxaban/ Apixaban |
Partially proven: confirmation should be done in plasma samples from patients treated with dabigatran and apixaban |
Not required | Only in specialized laboratories | ±100 to 200 ng/mL (depending on the reagent and the molecule)/no | Yes, but less importantly than for PT or aPTT | Not established |
aPTT: activated partial thromboplastin time; DRVV-T: dilute Russell's viper venom time; dTT: dilute thrombin time; ECA: ecarin chromogenic assay; ECT: ecarin clotting time; PT: prothrombin time; TT: thrombin time.
†Sensitivity is defined as the concentration required to double or to halve the clotting time (for chronometric assays) or the OD/min (for chromogenic assays), respectively.
‡Plasma concentrations of dabigatran >30 ng/mL frequently excess the maximal time measured on most coagulometers.