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Aspirin may prevent venous thromboembolic events after TKA
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Recently published results showed aspirin was not inferior to other anticoagulants and may provide similar protection from postoperative venous thromboembolism or death for patients undergoing total knee arthroplasty.
Brian R. Hallstrom, MD, and colleagues monitored clinical events for 90 days after surgery among a retrospective cohort of 41,537 patients who underwent primary TKA. Patients received aspirin only (30.9%), a non-aspirin anticoagulant agent (54.5%), aspirin plus anticoagulation (13%) or no pharmaco-prophylaxis (1.6%). Primary outcome was the first occurrence of venous thromboembolism or death, researchers wrote, while the secondary outcome was bleeding events.
Results showed 1.38% of patients experienced a venous thromboembolic event, of whom 4.79% received no pharmacologic prophylaxis; 1.16% received aspirin alone; 1.42% received anticoagulation alone; and 1.31% received both aspirin and anticoagulation. Researchers found 1.10% of patients experienced a bleeding event.
According to results, 1.5%, 0.90%, 1.14% and 1.35% of patients in the no prophylaxis group, the aspirin group, the anticoagulation group and the aspirin plus anticoagulation group, respectively, experienced a bleeding event. Compared with patients who received chemoprophylaxis, researchers found the only noninferiority for the composite venous thromboembolic outcome and for bleeding complications was aspirin alone. – by Casey Tingle
Disclosures: Hallstrom reports he receives partial salary support from Blue Cross and Blue Shield of Michigan as co-director of the Michigan Arthroplasty Registry Collaborative Quality Initiative. Please see the full study for a list of all authors’ relevant financial disclosures.
Perspective
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Vincent D. Pellegrini , MD
Hood and colleagues should be commended for attempting to further elucidate the vexing question of venous thromboembolism (VTE) prophylaxis after total joint arthroplasty, specifically TKA. Nevertheless, despite including more than 41,500 patients, their efforts represent yet another observational study rift with strong selection bias that limits the value and relevance of the data. Previous American Academy of Orthopaedic Surgeons guidelines advocated a risk stratification approach to chemoprophylaxis for VTE after TJA with aspirin being appropriate for the “usual” arthroplasty patient and more potent anticoagulants indicated in those patients with additional risk factors, such as prior VTE. Typically, 70% to 85% of patients receive aspirin and 15% to 30% receive more potent anticoagulants based upon individual surgeon risk assessment in a prior published series. The VTE group ratios in this study reflect an even stronger selection bias (30.9% aspirin only vs. 67.5% anticoagulant with or without aspirin) in Michigan, with only the healthiest and lowest risk patients receiving aspirin. Moreover, the declared noninferiority margin of 0.3% with an aggregate VTE and death rate of 1.6% represents a change of nearly 20%, which could be argued as being more inferior than most patients would accept for their management. As such, this study confirms that aspirin alone is sufficient VTE prophylaxis in the healthiest one-third of patients undergoing TKA. For the remaining majority of our patients, we remain in the dark until a randomized clinical trial can provide credible guidance on this question.
Department of orthopaedics and physical medicine
Adjunct professor of bioengineering
Charleston, South Carolina
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