Elizabeth Hofheinz, M.P.H., M.Ed.
A team of researchers from Mayo Clinic in Rochester, Minnesota recently examined data on primary total joint arthroplasties patients who were given either 81 mg or 325 mg of aspirin as a venous thromboembolism (VTE) chemoprophylaxis between 2000 and 2019. VTE included symptomatic pulmonary embolism and deep venous thrombosis.
Their retrospective cohort study, “Low-Dose vs Regular-Dose Aspirin for Venous Thromboembolism Prophylaxis in Primary Total Joint Arthroplasty,” was published in the February 6, 2021 edition of The Journal of Arthroplasty.
Co-author Matthew Abdel, M.D., a professor of orthopaedic surgery at Mayo, told OSN: “We were intrigued at comparing 81 mg of aspirin (ASA) vs. 325 mg of ASA twice-daily (BID) because of the recent literature in the cardiology field supporting 81 mg of ASA vs. 325 mg of ASA.”
Using the Mayo Clinic total joint registry, the researchers identified 29,140 primary TJAs (13,259 THAs and 15,881 TKAs) done between 2000 and 2019. Any patient who had received another form of VTE chemoprophylaxis, those treated with any other anti-thrombotic medications during the 6 weeks postoperative period, and those allergic to aspirin were excluded. Patients with a history of VTE were not eligible to participate in the study. The final analysis included 3,512 primary TJAs (2,344 total hip arthroplasties and 1,168 total knee arthroplasties).
Two times a day, patients were given aspirin (961 received 81 mg and 2,551 received 325 mg). In this study, for THAs, the mean age of patients who got 81 mg ASA was 67 years; 53% were female, and the mean body mass index (BMI) was 31 kg/m2. As for those who were treated with 325 mg ASA, the mean age was 66 years, 50% were female, and the mean BMI was 31 kg/m2. For those undergoing TKAs, the mean age of those who were given 81 mg ASA was 68 years; 54% were female, and the mean BMI was 31 kg/m2. Among TKA patients who were given 325 mg of aspirin, the mean age was 66; 60% were female, and the mean BMI was 31 kg/m2.
The authors, noting that the study was underpowered, stated that they found a cumulative incidence of VTE <1% at 90 days.
Dr. Abdel: “We were surprised to find that the cumulative incidence of VTE in this select group of healthy patients was 1% at 90 days, there were no GI bleeds in either group, and there was no difference in the 90-day mortality between either group.”
“In the future,” says Dr. Abdel, “we need to investigate if this regimen is safe in the revision setting, as well as those who are not as healthy.”
Dr. Abdel notes that he receives royalty payments from Stryker Corporation.