DELAYED ADMINISTRATION OF DIRECT ORAL ANTICOAGULANTS REDUCES TRANSFUSION RISK WHILE NOT INCREASING VENOUS THROMBOEMBOLISM RISK FOLLOWING REVISION TOTAL KNEE ARTHROPLASTY

Introduction Direct oral anticoagulants (DOACs) such as apixaban and rivaroxaban are effective prophylactic agents for preventing venous thromboembolism (VTE) following revision total knee arthroplasty (rTKA). However, the optimal timing for postoperative initiation of these agents is unclear. We sought to compare postoperative bleeding and venous thromboembolic complications among rTKA patients when the DOACs were administered on either postoperative day (POD) 0 versus POD 1. Methods A retrospective database was queried for patients who underwent aseptic rTKA from 2016–2023 and received apixaban or rivaroxaban on POD 0 compared to patients who received the same anticoagulant agent on POD 1. Ninety-day postoperative bleeding complications and venous thromboembolic complications were compared between cohorts for each medication. Multivariable logistic regression was used to assess differences. Results In total, 10,342 knees were identified, with 5,558 (53.7%) receiving apixaban and 4,784 (46.3%) receiving rivaroxaban. Of patients receiving apixaban, 1,160 (20.9%) began anticoagulation on POD 0 and 4,398 (79.1%) on POD 1. Apixaban POD 1 patients had a significantly decreased rate of transfusion (aOR: 0.70, 95%-CI:0.4937 – 0.9928, p=0.046) and aggregate bleeding complications (adjusted odds ratio [aOR]: 0.83, 95%-confidence interval (CI):0.7168 – 0.9636, p=0.014) compared to apixaban POD 0 patients. For rivaroxaban patients, 1,140 (23.8%) began anticoagulation on POD 0 and 3,644 (76.2%) on POD 1. Rivaroxaban POD 0 and POD 1 patients had similar rates of bleeding complications. Neither drug was associated with an increased risk of thromboembolic complications when administered on POD 1 versus POD 0. Discussion Delaying administration of apixaban until POD 1 was associated with a reduced risk of early postoperative transfusions and aggregate bleeding complications with no increased risk of venous thromboembolic complications following rTKA. In comparison, administration of rivaroxaban on POD 0 versus POD 1 led to no significant differences in bleeding or thromboembolic complications.