Chronic Anticoagulation in Patients Who Have Atrial Fibrillation Undergoing Outpatient Total Knee Arthroplasty: A Retrospective Matched Cohort Study

Background: Patients who have atrial fibrillation frequently require long-term anticoagulation with warfarin or a direct-acting oral anticoagulant (DOAC), such as apixaban or rivaroxaban, to avoid vascular complications. However, the impact of anticoagulant use on postoperative complications following total knee arthroplasty (TKA) in an outpatient setting has not been thoroughly elucidated. The purpose of this study was to examine the impact of anticoagulant use on early postoperative complications among atrial fibrillation patients undergoing outpatient TKA.

Methods: An insurance claims database was queried to identify all patients who underwent outpatient TKA between January 2010 and April 2022. There were two cohorts of patients, with associated 1:1 matched controls, who had atrial fibrillation and filled a prescription of either warfarin (N = 4,396) or DOAC (N = 5,383) for at least 30 days. The mean age was 70 years (range, 51 to 84), and 47.9% were women in the warfarin cohort, while the mean age was 70 years and 49.2% were women in the DOAC cohort. Postoperative 30-day medical and 90-day surgical complications were subsequently compared.

Results: Patients on warfarin had a higher incidence of pulmonary embolism (1.1 versus 0.2%, P < 0.001) and a lower incidence of TKA revision (0.1 versus 0.4%, P = 0.003) than matched controls. Similarly, patients on DOACs exhibited a higher incidence of pneumonia (1.4 versus 0.6%, P < 0.001) and myocardial infarction (3.2 versus 1.5%, P < 0.001) and a lower incidence of wound dehiscence (0.1 versus 0.5%, P < 0.001), joint infection (0.4 versus 0.9%, P = 0.002), and TKA revision (0.1 versus 0.4%, P = 0.002) than matched controls.

Conclusions: Atrial fibrillation patients on long-term anticoagulants undergoing outpatient TKA experience higher rates of medical complications and lower rates of surgical complications than matched controls. Thus, patients on long-term anticoagulants may be considered for outpatient TKA but should be counseled appropriately on associated medical risks.