MP16-14: Apixaban versus Enoxaparin for Post-surgical Extended Duration VTE Prophylaxis: A Prospective Quality Improvement Study

Mary Westerman*, New Orleans, LA, Kelly Bree, Cheryl Mantaring, Innocent Rukundo, Martha Garcia-Gonzalez, Ashlee Lafleur, Robbie Best, Colin Dinney, Ashish Kamat, Neema Navai, Louis Pisters, Christopher Wood, Jose Karam, John Papadopoulos, Lisly Chery, Mehrad Adibi, Brian Chapin, John Ward, Curtis Pettaway, John Davis, Justin Gregg, William Graber, Thomas Smith, O. Lenaine Westney, Desiree Valle, LaShena Crump, Raji Varghese, Miguel Saucedo, Jeff Cunningham, Kelly Casteel, Surena Matin, Houston, TX

Introduction: Venous thromboemobolic events (VTE) are a major cause of morbidity following abdominopelvic oncologic surgery. Enoxaparin, an injectable low molecular weight heparin, is commonly used for extended duration prophylaxis (EDP); however it has been associated with a high rate of patient non-compliance. Direct oral anticoagulants (DOACs)  have not been studied in the urologic oncology post-discharge setting.  In anticipation of a departmental practice change from enoxaparin to apixaban, we tested the hypothesis that apixaban was non-inferior to enoxaparin for post-operative EDP.

Methods: Following approval by the Quality Improvement Assessment Board, we prospectively collected data on all patients discharged with 28 days of EDP following urologic oncologic surgery. Enoxaparin 40mg daily and apixaban 2.5mg BID were prescribed at discharge during the baseline and intervention periods, respectively. Receipt of EDP was at the discretion of the operating surgeon.

Primary safety endpoint: symptomatic VTE or major bleeding event after discharge and within 30-days of surgery. Major bleed was defined according to International Society on Thrombosis and Hemostasis guidelines. We estimated events in 6.5% of enoxaparin and 4.0% of apixaban patients. Testing the null hypothesis that apixaban was non-inferior to enoxaparin with a pre-specified non-inferiority margin of = 4%, required 145 patients per group. The baseline period was set at six months based on previous discharge data.  Our intervention period was defined to last until at least 145 patients were discharged on apixaban with an option to stop at 6 months for futility.

Results: 160 patients were discharged with enoxaparin during the baseline period and 158 with apixaban during the intervention period. Major complications occurred in 3.5% of the enoxaparin group (2 [1.2%] major bleeds; 3 [1.8%] DVTs) and 0.0% for apixaban (p=0.06), meeting the pre-specified non-inferiority threshold. Minor bleeding complications occurred in 4.3% (7/160) and 4.4% (7/158) for enoxaparin and apixaban respectively (p=1.0).

Conclusions: Apixaban is non-inferior to enoxaparin for EDP after urologic oncology surgery. Apixaban may have a more favorable safety profile than enoxaparin and should be offered to patients who need EDP. Based on these results, apixaban is now our departmental standard.

Source of Funding: none