In this episode, I’ll discuss aspirin for VTE prophylaxis in orthopedic surgery.
When balancing bleeding and clotting risks, I find anecdotally that surgeons often place more emphasis on avoiding bleeding.
Years ago, when the CHEST Guidelines expanded the recommended medications for VTE prophylaxis in orthopedic surgery to include aspirin, pharmacists at my institution were hesitant but surgeons were excited about the possibility of efficacy with less bleeding.
A group of researchers recently published in Pharmacotherapy a 3 year multi-center retrospective cohort study of over 85,000 patients to better describe the odds of bleeding when rivaroxaban, enoxaparin, and aspirin are used for VTE prophylaxis following lower extremity joint arthroplasty or revision.
About three-quarters of the patients received aspirin, reflecting the popularity of this thromboprophylaxis strategy in an orthopedic surgery population.
The remaining patients were split almost evenly between the rivaroxaban and enoxaparin groups.
The primary outcome examined was all bleeding (major or minor), occurring in the 40 days following surgery. As a secondary outcome the incidence of venous thromboembolism was evaluated.
The incidence of bleeding was 1.20% in patients using rivaroxaban, 1.80% with enoxaparin, and 0.99% with aspirin.
When the different anticoagulants were compared directly to aspirin, enoxaparin has a statistically significant increased risk of bleeding with an odds ratio of 1.18. Rivaroxaban had a numerically greater risk of bleeding compared to aspirin but this did not reach statistical significance with a p value of 0.058.
There was no difference in the risk of venous thromboembolism between all three study groups.
The authors concluded:
Our study results suggest that aspirin is a safer alternative for use in postoperative thromboprophylaxis following lower extremity joint arthroplasty or revision.
Bleeding is rare in these surgeries which can make detection of small differences in bleeding rates challenging. While this is a retrospective study, some strengths include the large number of patients (over 85,000) and the multi-center design with data from over 140 institutions.
There were also additional benefits found in favor of aspirin – a lower hospital length of stay. The average length of stay (LOS) of patients receiving aspirin was 2.24 days compared to 2.75 days for rivaroxaban and 3.91 days for enoxaparin. The authors speculate on the reason for this finding:
The shorter LOS associated with aspirin is potentially due to less peri-wound oozing and hematoma formation, leading to fewer perioperative complications and decreased cost of hospitalization.
This study seems to justify the popularity of aspirin for VTE prophylaxis in orthopedic surgery.
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