1. N Engl J Med. 2018 Feb 22;378(8):699-707. doi: 10.1056/NEJMoa1712746.

Aspirin or Rivaroxaban for VTE Prophylaxis after Hip or Knee Arthroplasty.

Anderson DR(1), Dunbar M(1), Murnaghan J(1), Kahn SR(1), Gross P(1), Forsythe
M(1), Pelet S(1), Fisher W(1), Belzile E(1), Dolan S(1), Crowther M(1), Bohm
E(1), MacDonald SJ(1), Gofton W(1), Kim P(1), Zukor D(1), Pleasance S(1), Andreou
P(1), Doucette S(1), Theriault C(1), Abianui A(1), Carrier M(1), Kovacs MJ(1),
Rodger MA(1), Coyle D(1), Wells PS(1), Vendittoli PA(1).

Author information: 
(1)From the Departments of Medicine (D.R.A.), Surgery (M.D.), and Community
Health and Epidemiology (P.A.), Dalhousie University, and the Nova Scotia Health 
Authority (S. Pleasance, S. Doucette, C.T., A.A.), Halifax, the Department of
Surgery, University of Toronto, Toronto (J.M.), the Departments of Medicine
(S.R.K.) and Surgery (W.F., D.Z.), McGill University, and the Department of
Surgery, University of Montreal (P.-A.V.), Montreal, the Department of Medicine, 
McMaster University, Hamilton, ON (P.G., M. Crowther), the Department of Surgery,
Dalhousie University, Moncton, NB (M.F.), the Department of Surgery, Laval
University, Quebec, QC (S. Pelet, E. Belzile), the Department of Medicine,
Dalhousie University, Saint John, NB (S. Dolan), the Department of Surgery,
University of Manitoba, Winnipeg (E. Bohm), the Departments of Surgery (S.J.M.)
and Medicine (M.J.K.), University of Western Ontario, London, and the Department 
of Surgery (W.G., P.K.), Division of Hematology, Department of Medicine (M.
Carrier, M.A.R., P.S.W.), and School of Epidemiology and Public Health (D.C.),
University of Ottawa, Ottawa - all in Canada.

Comment in
    N Engl J Med. ;378(19):1848.

BACKGROUND: Clinical trials and meta-analyses have suggested that aspirin may be 
effective for the prevention of venous thromboembolism (proximal deep-vein
thrombosis or pulmonary embolism) after total hip or total knee arthroplasty, but
comparisons with direct oral anticoagulants are lacking for prophylaxis beyond
hospital discharge.
METHODS: We performed a multicenter, double-blind, randomized, controlled trial
involving patients who were undergoing total hip or knee arthroplasty. All the
patients received once-daily oral rivaroxaban (10 mg) until postoperative day 5
and then were randomly assigned to continue rivaroxaban or switch to aspirin (81 
mg daily) for an additional 9 days after total knee arthroplasty or for 30 days
after total hip arthroplasty. Patients were followed for 90 days for symptomatic 
venous thromboembolism (the primary effectiveness outcome) and bleeding
complications, including major or clinically relevant nonmajor bleeding (the
primary safety outcome).
RESULTS: A total of 3424 patients (1804 undergoing total hip arthroplasty and
1620 undergoing total knee arthroplasty) were enrolled in the trial. Venous
thromboembolism occurred in 11 of 1707 patients (0.64%) in the aspirin group and 
in 12 of 1717 patients (0.70%) in the rivaroxaban group (difference, 0.06
percentage points; 95% confidence interval [CI], -0.55 to 0.66; P<0.001 for
noninferiority and P=0.84 for superiority). Major bleeding complications occurred
in 8 patients (0.47%) in the aspirin group and in 5 (0.29%) in the rivaroxaban
group (difference, 0.18 percentage points; 95% CI, -0.65 to 0.29; P=0.42).
Clinically important bleeding occurred in 22 patients (1.29%) in the aspirin
group and in 17 (0.99%) in the rivaroxaban group (difference, 0.30 percentage
points; 95% CI, -1.07 to 0.47; P=0.43).
CONCLUSIONS: Among patients who received 5 days of rivaroxaban prophylaxis after 
total hip or total knee arthroplasty, extended prophylaxis with aspirin was not
significantly different from rivaroxaban in the prevention of symptomatic venous 
thromboembolism. (Funded by the Canadian Institutes of Health Research;
ClinicalTrials.gov number, NCT01720108 .).

DOI: 10.1056/NEJMoa1712746 
PMID: 29466159  [Indexed for MEDLINE]