Laboratory Tests in Assessing the Bleeding Risk in Patients Receiving Direct Oral Anticoagulants (DOACs)

Apixaban, rivaroxaban and dabigatran are direct oral anticoagulants (DOACs), which are often indicated for the prevention of stroke caused by atrial fibrillation and the management of venous thromboembolism. DOACs have gained wide use recently as alternatives to the traditional oralvitamin K antagonists (warfarin) therapy. However, the therapeutic benefit is not without risk of bleeding complications, such as hematuria and gastrointestinal bleeding. 

This study compared laboratory test results from 82 patients with and 361 patients without DOAC-associated bleeding with the goal of determining the value of laboratory tests in assessing bleeding risk in these patients. The clinical indications and dosing regimen of DOAC therapy were based on the clinically established as well as United States Food and Drug Administration (FDA) approved guidelines. The electronic medical charts of patients with DOAC therapy-associated bleeding complications were reviewed. Laboratory test results from all patients receiving DOAC therapy were reviewed with a focus on platelet count (reference range: 150 - 400 bil/L), prothrombin time (9.3 - 12.4 seconds), PTT (23.0 - 30.0 seconds), renal function tests: creatinine (0.60 - 1.40 mg/dL) and blood urea nitrogen (8 - 22 mg/dL) and liver function tests: aspartate aminotransferase (10 - 37 U/L), alanine aminotransferase (8 - 37 U/L), and alkaline phosphatase (30 - 110 U/L).

There was no age or gender difference between patients with and without DOAC therapy-associated bleeding complications. Both prothrombin time (PT) and partial thromboplastin time (PTT) prolonged at the same time showed good correlation with bleeding complications for patients receiving dabigatran (91.7%) and rivaroxaban (41.2%). When comparing patients with bleeding and those without bleeding complications, impaired renal function showed high correlation (p < 0.01), impaired liver function showed moderate correlation (p = 0.03), and thrombocytopenia showed no correlation (p > 0.05) among patients with bleeding complications. A small population of patients had never experienced bleeding complications, despite thelaboratory test results being similar to patients who suffered from bleeding complications.

In conclusion, laboratory tests may be useful in the assessment and prediction of bleeding risk in patients receiving DOAC therapy. And it is important to incorporate both laboratory findings and clinical information, such as concomitant antithrombotic agents and other underlying diseases, in the decision making of DOAC therapy in order to reduce therapy-related bleeding risk.

Article by Subhash Edupuganti, et al, from William Beaumont Hospital, Troy, USA.

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