The danger of relying on the APTT and PT in patients on DOAC therapy, a potential patient safety issue.

Prolongation of the activated partial thromboplastin time (APTT) and prothrombin time/international normalized ratio (PT/INR) correlates poorly with plasma concentrations of direct oral anticoagulant agents (DOACS) including direct thrombin and direct Xa inhibitors. It has been repeatedly demonstrated that patients can have normal APTT and PT/INR with a therapeutic plasma concentration of a DOAC. Clinicians can no longer rely on a normal APTT and PT to determine that an anticoagulated patient is safe to undergo an invasive procedure. Laboratory scientists need to play a key and active role in educating clinicians about the limitations of the APTT and PT in patients on DOAC prophylaxis or therapy.