Anderson DR, Dunbar M, Murnaghan J, et al. Aspirin or rivaroxaban for VTE
prophylaxis after hip or knee arthroplasty. New England Journal of Medicine. 2018;378(8):699-
707.
doi: https://doi.org/10.1056/nejmoa1712746

Summary by Alexis Kasper

Administration of anticoagulant prophylaxis after a total hip or knee arthroplasty has
been shown to reduce complications and death rates that are associated with venous
thromboembolism, or VTE.^1-3 Established guidelines have recommended that patients receive
anticoagulant prophylaxis for 14 days after surgery.⁴

Anderson et al. conducted a prospective study that evaluated the efficacy of aspirin, an
inexpensive and widely used antiplatelet drug, in preventing venous thromboembolism. The
researchers assessed the effectiveness and safety of extended prophylaxis with aspirin and
compared it to rivaroxaban, a typical direct oral anticoagulant. All patients were given in-
hospital prophylaxis with rivaroxaban starting on the day of surgery until postoperative day 5.
Then the participants who underwent total knee arthroplasty were randomly assigned to continue
to receive thromboprophylaxis with rivaroxaban for the remaining 9 days or were told to take
aspirin instead of the rivaroxaban. Similarly, those who underwent a total hip arthroplasty were
placed into either of the above groups but for 30 days, since it was suggested that prophylaxis
can continue for up to 35 days after surgery.⁴

Effectiveness and safety were both evaluated as trial outcomes. The primary effectiveness
outcome was adjudicated symptomatic VTE while the primary safety outcomes were major and
any bleeding. Secondary outcomes included death, stroke, myocardial infarction, and wound
infection, according to Anderson et al. The researchers found no significant between-group
differences in VTE, major bleeding, and any bleeding. Out of the 1717 patients who took only
rivaroxaban, 12 presented with VTE, 5 experienced major bleeding, and 17 experienced any
bleeding. Similarly, out of the 1707 patients who took rivaroxaban and then switched over to aspirin, 11 patients presented with VTE, 8 patients experienced major bleeding, and 22 patients
experienced any bleeding.

In conclusion, Anderson et al. found that aspirin was not significantly different from an
oral anticoagulant such as rivaroxaban for preventing venous thromboembolism, and, therefore,
aspirin can be a safe and effective choice for preventing VTE after a total hip or knee
arthroplasty.

References:

1. Hull RD, Pineo GF, Stein PD, et al. Extended out-of-hospital low-molecularweight
2. heparin prophylaxis against deep venous thrombosis in patients after elective hip
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4. Eikelboom JW, Quinlan DJ, Douketis JD. Extended-duration prophylaxis against venous
   thromboembolism after total hip or knee replacement: a meta-analysis of the randomised
   trials. Lancet 2001;358: 9-15.
5. O’Donnell M, Linkins LA, Kearon C, Julian J, Hirsh J. Reduction of out-of-hospital
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   molecular-weight heparin following elective hip arthroplasty: a systematic review. Arch
   Intern Med 2003;163:1362-6.
6. Falck-Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery
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