Commentary on the manuscript “Aspirin or Rivaroxaban for VTE Prophylaxis after Hip or Knee Arthroplasty”

February 22, 2018

Jawed Fareed, PhD
Rakesh Wahi, MD

Venous thromboembolic disease presents a significant challenge to the surgical patients and especially for the patients undergoing orthopedic procedures. The use of artificial devices and cements under pressure presents a significant challenge for homeostasis by creating a highly thrombogenic environment. Historical data indicates that the patients undergoing orthopedic procedures are at considerable risk for venous thromboembolism (VTE) and a fatal pulmonary embolism (PE), historically reported at  1 to 2% of the patients and as high as 5 to 10% in those undergoing surgery for hip fracture. It is generally believed that the thromboembolic activity begins during the surgical procedure while it takes as long as six hours for a venous clot to actually form. The risk for thromboembolic disease remains elevated postoperative even after hospital discharge (1).

The first successful attempt to reduce the incidence of fatal pulmonary embolism was reported in a multi-institutional study led by Kakkar in 1976 which eliminated the risk of for fatal pulmonary embolism by using low dose heparin preoperatively. Despite multiple trials demonstrating the efficacy of the instituting a prophylactic regimen preoperatively, there has been a reluctance to administer the agents preoperatively in orthopedic surgery.  Recognizing that the risk for VTE remains slightly elevated in the late post operative period there continues to be the search for agents that can be administered prophylactically during surgery and can be easily continued by the patient on an outpatient basis.

 This manuscript confirms that there is a higher risk of developing VTE in the early postoperative period which can be neutralized by the use of rivaroxaban. The prophylaxis is initiated postoperatively and continued postoperatively for as long as 30 days. As predicted by the results from an earlier PEP Trial, the current study found that aspirin is quite efficacious in reducing the incidence of VT E in the thrombotically less challenging post operative period (2).

There appears to be an acceptance of a low incidence for fatal pulmonary embolism in this trial. It would be useful to carry out a trial where the prophylaxis is begun preoperatively. It is noteworthy to acknowledge a large observational study from Norway where 20,241 patients undergoing treatment for femoral neck factors were studied (3). The patients were divided into groups that received preoperative prophylaxis and in whom the prophylaxis began postoperatively.  The authors noted a significant reduction in all cause 30 day mortality (7.7%) in patients receiving preoperative prophylaxis (7.7 % vs. 8.5 % P value 0.001) compared to those getting postoperative prophylaxis. The risk of seven-day reoperation was .1% in patients receiving preoperative prophylaxis compared to 0.3% in patients receiving postoperative prophylaxis. At 30 days the risk of the reoperation for hematoma was .3% in the group receiving preoperative prophylaxis in .2% in the group receiving the prophylaxis. This study shows a significant mortality benefit with very little hemorrhagic risk in patients that receive preoperative prophylaxis.

Aspirin alone remains a reasonable alternative to patients who should not receive anticoagulants. This is supported by recent observational study of approximately 18,000 patients where subjects were retrospectively stratified into those receiving aspirin for prophylaxis versus those receiving warfarin prophylaxis (4). In this study there was an incidence of pulmonary embolism at a rate of 1.05% in patients receiving aspirin compared to 2.3% in the patients receiving warfarin prophylaxis.

Aspirin prophylaxis of DVT in VTE is now standard of care in patients undergoing joint arthroplasty. It provides long term prophylaxis of DVT, VTE and offer anti-inflammatory responses. Om a cost basis it is a much cheaper option then rivaroxaban or other related drugs. More importantly the bleeding complications with aspirin are likely to be much less than oral anticoagulants such as rivaroxaban thus aspirin remains to be the drug of choice for the prophylaxis of VTE after hip or knee arthroplasty. 

References

  1. Huber O, Bouneameaux H, Borsi F, Rohner A Arch Surg 127: 1992 Mar 310-313
    Postoperative pulmonary embolism after hospital discharge; an underestimated risk

  2. The PEP collaborative Group . Prevention of pulmonary embolism and deep venous thrombosis with low-dose aspirin; pulmonary embolism prevention (PEP) trial.

    The Lancet 2000, volume 355 9212 pages 1295 – 1302
  3. Sunniva Leer-Salvesen, Eva Dybvik, Ola E Dahl, Jan-Erik Gjertsen & Lars B EngesæTer  (2017) Postoperative start compared to preoperative start of low-molecular- weight heparin increases mortality in patients with femoral neck fractures, Acta Orthopaedica, 88:1, 48-54,

  4. R. Goel, A. N. Fleischman, T. Tan, E. Sterbis, R. Huang, C. Higuera, J. Parvizi, R. H. Rothman. Venous thromboembolic prophylaxis after simultaneous bilateral total knee arthroplasty. ASPIRIN VERSUS WARFARIN Bone Joint J 2018;100-B(1 Supple A):68–75.