In the JournalsPerspective

Study: Unfractionated heparin should not be used with aspirin following THA, TKA as VTE prophylaxis

Investigators of a study published in Orthopedics said unfractionated heparin should not be used as an additional mode of venous thromboembolism prophylaxis when aspirin is prescribed in patients who underwent total hip arthroplasty or total knee arthroplasty.

Ali H. Sobh

“Postoperative unfractionated heparin in addition to aspirin for venous thromboembolism prophylaxis is not superior to aspirin monotherapy,” Ali H. Sobh, MD, told Healio.com/Orthopedics. “[Unfractionated heparin] UH and [aspirin] ASA combination therapy is associated with increased rates of perioperative blood loss and postoperative allogeneic blood transfusion."

Sobh and colleagues performed a retrospective review and identified 5,350 patients who underwent either total hip arthroplasty or total knee arthroplasty. Based on VTE chemoprophylaxis, 1,024 patients received aspirin only; 1,695 patients received aspirin and one dose of unfractionated heparin; and 2,621 patients received aspirin and multiple doses of unfractionated heparin. Patient age, sex, BMI, American Society of Anesthesiologists score, smoking status, joint, OR time, history of deep venous thrombosis and preoperative hemoglobin were other independent variables included in the model.

Results showed the treatment groups were not significantly different with regard to DVT rates and pulmonary embolus rates. Compared with patients who received aspirin only, patients who received one dose of unfractionated heparin and multiple doses of unfractionated heparin had significantly greater transfusion rates. Investigators noted the use of unfractionated heparin significantly decreased postoperative hemoglobin. Compared to aspirin monotherapy, aspirin and unfractionated heparin combination therapy did not decrease the incidence of VTE. Patients who received unfractionated heparin had a greater perioperative blood loss and had an increased rate of blood transfusions. – by Monica Jaramillo

 

Disclosures : The authors report no relevant financial disclosures.

Investigators of a study published in Orthopedics said unfractionated heparin should not be used as an additional mode of venous thromboembolism prophylaxis when aspirin is prescribed in patients who underwent total hip arthroplasty or total knee arthroplasty.

Ali H. Sobh

“Postoperative unfractionated heparin in addition to aspirin for venous thromboembolism prophylaxis is not superior to aspirin monotherapy,” Ali H. Sobh, MD, told Healio.com/Orthopedics. “[Unfractionated heparin] UH and [aspirin] ASA combination therapy is associated with increased rates of perioperative blood loss and postoperative allogeneic blood transfusion."

Sobh and colleagues performed a retrospective review and identified 5,350 patients who underwent either total hip arthroplasty or total knee arthroplasty. Based on VTE chemoprophylaxis, 1,024 patients received aspirin only; 1,695 patients received aspirin and one dose of unfractionated heparin; and 2,621 patients received aspirin and multiple doses of unfractionated heparin. Patient age, sex, BMI, American Society of Anesthesiologists score, smoking status, joint, OR time, history of deep venous thrombosis and preoperative hemoglobin were other independent variables included in the model.

Results showed the treatment groups were not significantly different with regard to DVT rates and pulmonary embolus rates. Compared with patients who received aspirin only, patients who received one dose of unfractionated heparin and multiple doses of unfractionated heparin had significantly greater transfusion rates. Investigators noted the use of unfractionated heparin significantly decreased postoperative hemoglobin. Compared to aspirin monotherapy, aspirin and unfractionated heparin combination therapy did not decrease the incidence of VTE. Patients who received unfractionated heparin had a greater perioperative blood loss and had an increased rate of blood transfusions. – by Monica Jaramillo

 

Disclosures : The authors report no relevant financial disclosures.

    Perspective
    Andreas F. Mavrogenis

    Andreas F. Mavrogenis

    In this article, the authors studied aspirin-only, and aspirin combined with UH for VTE prophylaxis after elective primary total hip arthroplasty and total knee arthroplasty. They found similar VTE events, but shorter hospital stays, higher hemoglobin values and lower blood transfusion requirements in the aspirin-only group.

    There are no studies that directly compare aspirin-only with aspirin and UH for VTE prophylaxis after elective primary THA and TKA. Therefore, the present study gives useful information to surgeons who choose to administer these pharmacologic agents for VTE prophylaxis of their patients. Based on the study’s results, UH as an additional mode of VTE prophylaxis when prescribing aspirin in these patients is not recommended.

    As expected, aspirin in addition to UH showed a synergic action and increased complications (lower hemoglobin values and higher transfusion requirements); the similar VTE prophylaxis effect can be explained by the different mechanism of action of the two drugs in the coagulation cascade.

    Available guidelines recommend low molecular-weight heparin (LMWH) over other agents for VTE prophylaxis. In this context, the study seems outdated as not many surgeons/hospitals currently apply these protocols for VTE prophylaxis of their patients undergoing elective primary THA and TKA. It would have been more useful if the authors had compared aspirin-only with LMWH, which is the preferred option for VTE prophylaxis, according to most guidelines.

    Adherence to guidelines with respect to preference, doses, time of initiation and duration of treatment in clinical practice is another concern. The authors refer to their own protocol and the American Academy of Orthopaedic Surgeons 2011 guidelines for prophylaxis; UH was given as a 5000-IU subcutaneous injection based on historical studies and hospital postoperative protocol, and aspirin was given as a 325-mg twice-daily dose for 28 days.

    Last, and most importantly, VTE can occur up to 3 months after THA and TKA. As clarified by the authors, in this series the patients were not routinely checked for VTE; therefore, subclinical VTE was not included in the analysis, which is a major limitation of the study.

    Reference:

    Flevas DA, et al. EFORT Open Rev.2018 doi:10.1302/2058-5241.3.170018.

    • Andreas F. Mavrogenis, MD
    • Assistant professor of orthopaedics National and Kapodistrian University of Athens, School of Medicine Athens

    Disclosures: Mavrogenis reports no relevant financial disclosures.