Hi or Low Dose Aspirin to Prevent Infection? New Study

Researchers from Rothman Orthopaedic Institute at Thomas Jefferson University in Philadelphia and the University of California Los Angeles set out with this question in mind: “How does a total daily dose of 162mg of aspirin stack up against a total of 650mg per day when it comes to reducing periprosthetic joint infection (PJI) following total joint arthroplasty (TJA)—without increasing the risk of postoperative wound complications?”

Their work, “Low-Dose Aspirin for Venous Thromboembolism Prophylaxis is Associated With Lower Rates of Periprosthetic Joint Infection After Total Joint Arthroplasty,” was published in the July 14, 2022 edition of The Journal of Arthroplasty.

Co-author Farideh Najafi, M.D. told OTW, “PJI remains a serious postoperative complication associated with significant morbidity, mortality, and healthcare cost. Given the rapidly increasing number of total joint arthroplasties (TJAs), the burden of PJI is expected to increase, with current data suggesting an incidence of PJI following TJA ranging from 1 to 4.6%.”

“Post-operatively, a robust immune response is critical to prevent the adherence of bacteria and the development of biofilm. Peri-operative modifications of the host immune response can facilitate the prevention of PJI development. Interestingly, aspirin, which is routinely administered post-operatively as a venous thromboembolism event prophylaxis, has a potential anti-staphylococcal and anti-biofilm role. In recent years, the orthopaedic communities have accepted the antiplatelet agent aspirin as the primary venous thromboembolism event prophylactic method following total joint arthroplasty.”

“It has been demonstrated that aspirin has a direct antibacterial effect, with potent anti-staphylococcal synergy with concomitant antibiotic administration. As platelets have potent anti-microbial properties and platelet deficiency is strongly linked to PJI severity in a pre-clinical model, an optimal aspirin dose would facilitate anti-microbial effects, while avoiding over-aggressive inhibition of platelet anti-microbial function. While some studies suggest that using aspirin as a venous thromboembolism event prophylaxis method reduces PJI risk following TJA, there is no study to evaluate if aspirin dose after joint arthroplasty will affect the rate of PJI.”

“We hypothesized that using 81mg bid of aspirin (162mg total daily dose) will be more effective than 325mg bid (650mg total daily dose) at reducing PJI following TJA, without increasing the risk of postoperative wound complications.”

The researchers studied 15,825 patients, 8,761 of whom received venous thromboembolism event prophylaxis with low-dose aspirin and 7,064 patients who received high-dose aspirin. They determined that more individuals in the low-dose aspirin cohort had a history of diabetes (7.1 vs. 2.5%) and received tranexamic acid during the surgery (82.9 vs. 51.3%).

According to the authors, “Patients in the high-dose cohort were more likely to undergo total knee arthroplasty (TKA) (48.1 vs. 41.3%), undergo total hip arthroplasty (THA) through a lateral approach (60.7 vs. 39.5%), have bilateral surgery (7.4 vs. 2.0%), receive a general anesthetic (3.9 vs. 2.9%), and have tourniquet usage during the surgery (69.9 vs. 29.8%). Also, high-dose cohort patients had more blood loss (128 vs. 103 mL) and transfusion rates (4.0 vs. 1.9%). In the combined cohort, there were no statistically significant differences in rates of post-operative myocardial infarction, cerebrovascular accident, gastrointestinal ulceration, or gastrointestinal hemorrhage.”

“The high-dose aspirin cohort had a higher PJI rate than low-dose aspirin cohort,” commented Dr. Najafi to OTW. “This relationship was maintained when comparing subgroups comprising TKA or THA, and accounting for potentially confounding demographic and surgical variables.”