Laboratory and Clinical Monitoring of Direct Acting Oral Anticoagulants: What Clinicians Need to Know

The direct acting oral anticoagulants (DOACs), including dabigatran, rivaroxaban, apixaban, and edoxaban, have favorable pharmacokinetic and pharmacodynamic properties and equal or superior efficacy and an improved safety profile compared with warfarin. Noted shortcomings with DOACs are shorter half-lives requiring stricter adherence, lack of standardized laboratory monitoring, lack of anticoagulation reversal agents, and loss of routine coagulation monitoring leading to fewer patient-clinician interactions. This review addresses many of these limitations including monitoring of DOACs for efficacy and toxicity, an assessment of selected qualitative and quantitative tests, and development of monitoring strategies for special populations. Coagulation monitoring is generally recommended only in overdose situations, but once standardized assays are readily available, they could be helpful to ensure efficacy, assess bleeding, and aid in drug selection in a number of other patient scenarios. Coagulation tests that may provide qualitative assessment include activated partial thromboplastin time, prothrombin time, and thrombin time. Methods with potential utility for quantitative assessment of DOACs include plasma drug concentrations, ecarin clotting time, dilute thrombin time, and anti-factor Xa concentrations. Noncoagulation laboratory monitoring should include serum creatinine, liver function tests, and complete blood counts. Clinical monitoring of the DOAC-treated patient should include routine assessment of adherence, bleeding risks, and drug interactions. Frequency of monitoring should be 1-3 months after initiation and then at least every 6 months, with more frequent follow-up (i.e., 3 months) based on patient specific characteristics such as age, renal impairment, hepatic impairment, and concomitant drug therapy. The authors provide a practical tool to assist in DOAC monitoring and recommend that pharmacists collaborate with physicians in selecting appropriate patients and tailoring patient-specific monitoring plans.