Direct Oral Anticoagulants: How Do These Drugs Work, How to Monitor, and What Is Their Role in Orthopaedic Surgery

Abstract

Postoperative venous thromboembolism is a major adverse event associated with orthopaedic surgery. With the addition of perioperative anticoagulation and antiplatelet therapy, the rates of symptomatic venous thromboembolism have dropped to 1% to 3%, and as such, practicing orthopaedic surgeons must be familiar with these medications, including aspirin, heparin, or warfarin, and the use of direct oral anticoagulants (DOACs). DOACs are increasingly being prescribed due to their predictable pharmacokinetics and increased convenience, as they do not require routine monitoring, and 1% to 2% of the general population is currently anticoagulated. Although the introduction of DOACs has yielded additional treatment options, this has also led to confusion and uncertainty regarding treatment, specialized testing, and when and what reversal agents are appropriate. This article provides a basic overview of DOAC medications, their suggested use in the perioperative setting, effects on laboratory testing, and consideration for when and how to use reversal agents in orthopaedic patients.A host of factors lead to a prothrombotic state in orthopaedic surgery (OS), including utilization of operational tourniquets, localized vascular injury during surgical manipulation, use of prothrombotic surgical materials including cement, and subsequent immobility during recovery. 1,2 These factors have historically led to rates of VTE and fatal PE, approaching 50% and up to 20%, respectively. 3 With implementation of anticoagulant therapy, modification of surgical techniques, and earlier mobilization of patients, the incidence of VTE/fatal PE reported with OS has progressively declined to around 1% to 3%. 1,2,4 Oral vitamin K antagonists (VKAs) such as warfarin (Coumadin) have historically served as the primary oral anticoagulant in this setting, with subsequent adoption of heparin for inpatients. Although utilization of VKAs led to a substantial drop in thromboembolic events associated with OS, these anticoagulants have inherent disadvantages such as drug interactions,

Challenges to Laboratory Monitoring of Direct Oral Anticoagulants

“… 26 Perioperative DOAC DLM is supported due to concerns pertaining to DOAC pharmacodynamics and pharmacokinetics that impact efficacy and safety in the setting orthopedic surgery. 27 In a multicenter cohort study of 1065 patients, 232 patients had preoperative DOAC DLM but reported worsened outcomes compared to the patients without preoperative DLM. 28 Major limitations of this retrospective cohort study include selection bias and lack of randomization; patients who received the most DOAC DLM included high-risk bleeding surgical procedures, including spinal, orthopedic, and neurosurgical procedures.…”