1. Patients initially treated with rivaroxaban following total knee or hip arthroplasty experienced similar rates of venous thromboembolism (VTE) regardless of continued rivaroxaban use or switching to aspirin for extended VTE prophylaxis.
2. No significant difference in rates of major bleeding complications was observed between aspirin and rivaroxaban treated groups.
Evidence Rating Level: 1 (Excellent)
Study Rundown: VTE is a serious adverse event following knee or hip arthroplasty. Use of prophylactic anticoagulants has reduced morbidity when administered both immediately after and for extended periods following surgery. While direct oral anticoagulants are often prescribed for extended VTE prophylaxis in part due to patient convenience, use of aspirin may provide a more cost-effective option. The EPCAT II (Extended Venous Thromboembolism Prophylaxis Comparing Rivaroxaban to Aspirin Following Total Hip and Knee Arthroplasty II) trial compares effectiveness and safety profiles of aspirin to rivaroxaban for use in extended VTE prophylaxis. At 90 days post total hip or knee arthroplasty, no difference in rates of VTE was observed between the aspirin and rivaroxaban groups. Additionally, no difference in bleeding complications was observed between the groups.
Strengths of the study include its large sample size and high rate of patient follow-up, and a limitation includes lack of comparison of VTE strategies immediately post-operatively. This study provides strong evidence supporting the use of aspirin as a cost-effective medication with comparable safety and efficacy profiles to rivaroxaban for extended VTE prophylaxis in arthroplasty patients.
Click to read the study in NEJM
Relevant Reading: Aspirin for prevention and treatment of venous thromboembolism
In-Depth [randomized controlled trial]: This multicenter, randomized, controlled trial was conducted between 2013 and 2016. Eligible patients were undergoing unilateral total hip or knee arthroplasty, and those with recent fractures or metastatic cancer were excluded. Patients (n = 3427) received rivaroxaban following surgery until postoperative day 5 and were then randomized to receive either rivaroxaban (n = 1718) or aspirin (n = 1719). Knee arthroplasty patients received 9 days of extended VTE prophylaxis and those who underwent hip arthroplasty received 30 days of prophylaxis. The primary outcome was symptomatic VTE within 90 days, and the main safety outcome was significant bleeding rate.
VTE occurred in 0.64% of patients in the aspirin group and 0.70% of rivaroxaban treated patients (difference, 0.06 percentage points; 95% confidence interval [CI], –0.55 to 0.66; aspirin noninferiority, p < 0.001; aspirin superiority, p = 0.84). Major bleeding occurred at similar rates in 0.47% and 0.29% of aspirin and rivaroxaban treated patients, respectively (difference, 0.18 percentage points; 95% CI, −0.65 to 0.29; p = 0.42), with most bleeding occurring within 10 days post-operatively. Rates of VTE and bleeding did not significantly differed between patients undergoing total hip or knee arthroplasty.
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