Rate of Transfusions After Total Knee Arthroplasty in Patients Receiving Lovenox or High-Dose Aspirin

Controversy continues regarding the use of powerful anticoagulants for venous thromboembolism prophylaxis in patients undergoing total knee arthroplasty (TKA). To comply with institution-mandated guidelines and pressure from hospitalist intent on complying with conventionally recommended anticoagulation guidelines, we singularly changed our chemoprophylaxis practice from using aspirin to Lovenox and noted that transfusion rates increased substantially.

A retrospective case review was performed to evaluate transfusion requirement differences in primary TKA patients receiving Lovenox (unilateral TKA: n = 135, bilateral TKA: n = 44) or aspirin (unilateral TKA: n = 153, bilateral TKA: n = 45) for venous thromboembolism prophylaxis. Pearson's chi-square tests were used to evaluate surgical complications and the rate of transfusions between aspirin and Lovenox groups. Independent t tests were used to evaluate the units of packed red blood cells transfused, hemoglobin drop, and hematocrit drop between aspirin and Lovenox groups.

Lovenox was found to significantly increase (P < .01) the rate of transfusion, units of packed red blood cells, hemoglobin drop, and hematocrit drop compared to aspirin in both unilateral and bilateral TKA patients, without significantly decreasing venous thromboembolism events (aspirin: 3 pulmonary embolisms and 4 deep venous thrombosis; Lovenox: 3 pulmonary embolisms and 2 deep venous thrombosis).

Our findings suggest that aspirin is as effective as Lovenox in preventing venous thromboembolism and that the use of Lovenox significantly increases the likelihood of requiring transfusions after surgery.