Prevention of Venous Thromboembolism after Total Hip or Knee Replacement.
Vincent D Pellegrini, Carol A Lambourne, Laurence S Magder et al.
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In 30 seconds
This multicenter randomized comparative-effectiveness noninferiority trial compared 30 days of aspirin, warfarin, or rivaroxaban for VTE prophylaxis after elective total hip or knee arthroplasty. In the primary per-protocol analysis, six-month death or symptomatic VTE risks were 1.24% with aspirin versus 0.94% with rivaroxaban and 1.24% versus 1.01% with warfarin. Aspirin was not shown to be noninferior to either anticoagulant for effectiveness; neither anticoagulant was shown to be noninferior to aspirin for the composite safety outcome.
Key findings
- Six-month death or symptomatic VTE risk was 1.24% with aspirin and 0.94% with rivaroxaban (difference, 0.30 percentage points; 95% CI, -0.20 to 0.81).
- For aspirin versus warfarin, six-month effectiveness risks were 1.24% and 1.01% (difference, 0.23 percentage points; 95% CI, -0.34 to 0.81).
- Safety outcome risks were 3.70% with rivaroxaban versus 3.02% with aspirin, and 3.65% with warfarin versus 2.88% with aspirin.
Why it matters
VTE prophylaxis after hip or knee replacement requires balancing prevention of symptomatic thromboembolism against bleeding and other safety events. This trial directly compared commonly used regimens and found that aspirin did not meet the prespecified noninferiority standard for effectiveness, while the anticoagulants did not meet it for safety. The results clarify the limits of claiming equivalence between these options.
What to keep in mind
The primary per-protocol analysis included 15,317 of 18,883 randomized participants; the abstract does not provide reasons for exclusion. The reported outcomes were composite measures.