Background: Aspirin (ASA) is an effective chemical prophylaxis for venous thromboembolism (VTE) after total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, the optimal dosage and duration of therapy remains debatable. The main objective of this study was to compare two ASA regimens with regard to the incidence of symptomatic deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding (based on patient’s dressing), and infection within 90 days after primary THA and TKA.
Methods: We retrospectively identified 625 primary THA and TKA surgeries among 483 patients who received aspirin for four weeks post operatively. A total of 301 patients received 325 mg once daily and 324 patients received 81 mg twice daily. Patients were excluded if they were less than 18 years old, had a prior history of VTE event, had a documented ASA allergy, were receiving another agent for VTE chemoprophylaxis, or were receiving any other anti-thrombotic or anti-platelet medication during the immediate four-week post-operative period.
Results: There was a statistically significant difference in bleeding rates between the two aspirin regimens. Bleeding was 7.6% in the 325 mg once daily group and 2.5% in the 81 mg twice daily group (P = 0.0029). The rates of VTE, symptomatic DVT, and PE were not statistically significant. The incidence of VTE was 2.7% in the 325 mg once daily group and 1.5% in the 81 mg twice daily group (P = 0.4056). Symptomatic DVT rate was 1.6% in the 325 mg once daily group and 0.9% in the 81 mg twice daily group (P = 0.4139). Deep infection was 1.0% in the 325 mg once daily group and 0.31% in the 81 mg twice daily group (P = 0.3564).
Conclusion: Use of low dose ASA in patients with limited comorbidities undergoing primary THA or TKA demonstrates statistically significant lower bleeding rates compared to high dose ASA. Low dose ASA was not inferior to higher dose ASA for the prevention of VTE, wound complications, or infection within 90 days post-operatively.
Level of Evidence: III, retrospective study
