Comparable efficacy of 100 mg aspirin twice daily and rivaroxaban for venous thromboembolism prophylaxis following primary total hip arthroplasty: a randomized controlled trial

Background: Aspirin has demonstrated safety and efficacy for venous thromboembolism (VTE) prophylaxis following total hip arthroplasty (THA); however, inconsistent dose regimens have been reported in the literature. This study aimed to evaluate and compare the safety and efficacy of 100 mg aspirin twice daily with rivaroxaban in VTE prophylaxis following THA. Methods: Patients undergoing elective unilateral primary THA between January 2019 and January 2020 were prospectively enrolled in the study and randomly allocated to receive 5 weeks of VTE prophylaxis with either oral enteric-coated aspirin (100 mg twice daily) or rivaroxaban (10 mg once daily). Medication safety and efficacy were comprehensively evaluated through symptomatic VTE incidence, deep vein thrombosis (DVT) on Doppler ultrasonography, total blood loss (TBL), laboratory bloodwork, Harris hip score (HHS), post-operative recovery, and the incidence of other complications. Results: We included 70 patients in this study; 34 and 36 were allocated to receive aspirin and rivaroxaban prophylaxis, respectively. No cases of symptomatic VTE occurred in this study. The DVT rate on Doppler ultrasonography in the aspirin group was not significantly different from that in the rivaroxaban group (8.8% vs. 8.3%, chi(2) = 0.01, P = 0.91), confirming the non-inferiority of aspirin for DVT prophylaxis (chi(2) = 2.29, P = 0.01). The calculated TBL in the aspirin group (944.9 mL [658.5-1137.8 mL]) was similar to that in the rivaroxaban group (978.3 mL [747.4-1740.6mL]) (chi(2) = 1.55, P = 0.12). However, there were no significant inter-group differences in HHS at post-operative day (POD) 30 (Aspirin: 81.0 [78.8-83.0], Rivaroxaban: 81.0 [79.3-83.0], chi(2) = 0.43, P = 0.67) and POD 90 (Aspirin: 90.0 [89.0-92.0], Rivaroxaban: 91.5 [88.3-92.8], chi(2) = 0.77, P = 0.44), the incidence of bleeding events (2.9% vs. 8.3%, chi(2) = 0.96, P = 0.33), or gastrointestinal complications (2.9% vs. 5.6%, chi(2) = 1.13, P = 0.29). Conclusion: In terms of safety and efficacy, the prophylactic use of 100 mg aspirin twice daily was not statistically different from that of rivaroxaban in preventing VTE and reducing the risk of blood loss following elective primary THA. This supports the use of aspirin chemoprophylaxis following THA as a less expensive and more widely available option for future THAs.