No Increased Risk of Venous Thromboembolism in High-Risk Patients Continuing Their Dose of 75 mg Aspirin Compared to Healthier Patients Given Low-Molecular-Weight Heparin.

Background: Optimum venous thromboembolism (VTE) prophylaxis for patients undergoing total hip or knee arthroplasty remains undefined. The purpose of this study is to compare complication rates among total joint arthroplasty patients using either low-dose aspirin (75 mg once daily) or low-molecular-weight heparin (LMWH; Fragmin/dalteparin 5000 U) for VTE prophylaxis.

Methods: This is a prospective observational study. All total hip or knee arthroplasties from 2014 to 2020 were included. One thousand eighty-four patients already taking aspirin 75 mg as primary or secondary prophylaxis for cardiovascular disease continued their daily aspirin dose throughout their hospital stay and after discharge without any other kind of thromboprophylaxis. Five thousand ten patients not already taking aspirin were given LMWH for 12-14 days starting the day of surgery. Both groups consisted of patients undergoing either primary or revision total hip or knee arthroplasty. The aspirin group was older (73 ± 7.8 vs 66 ± 10.2 years, P < .01, 95% CI -7.6, -6.3) with more comorbidities but otherwise did not differ from the LMWH group. Outcome measures were recorded at 3-month follow-up and included the following complications: clinically deep venous thrombosis (DVT), pulmonary embolism (PE), deep infection, blood transfusion, and death.

Results: The aspirin group had 0.28% DVT and 0.28% PE, and the LMWH group had 0.24% DVT and 0.16% PE (P = .42 and .74, respectively). No difference in deep infection, allogenic blood transfusion, or mortality was found.

Conclusion: No statistically significant difference in complication rates was found between aspirin 75 mg and LMWH used for VTE prophylaxis. Aspirin 75 mg daily is safe for VTE prophylaxis after total hip or knee arthroplasty.