Clinical laboratory testing of blood from patients presenting to the emergency department with acute bleeding due to factor Xa inhibitors: An unmet medical need.

Bleeding is a life-threatening side effect of oral anticoagulants and can be a medical emergency. For patients on warfarin, stat testing of blood for the prothrombin time and calculation of the International Ratio (PT-INR) are used to determine if acute bleeding is caused by excess anticoagulation. Direct acting oral anticoagulants (DOACs) include those that inhibit Factor Xa (apixaban, rivaroxaban, edoxaban, and betrixaban) or Factor IIa (dabagatran). Unlike warfarin, there are no recommendations for regular monitoring of DOAC drug levels. Testing is useful for bleeding patients if a reversal agent is being considered. In addition, the use of thrombolytic therapy is contraindicated for the treatment of an ischemic stroke for a patient on a DOAC. However, current laboratory assays for anti-Factor Xa are calibrated for the specific DOAC used and results are not typically available in emergency departments. Therefore, there is a need to produce a rapid bedside blood test that can detect bleeding to any DOAC drug that was prescribed.