Journal of vascular surgery. Venous and lymphatic disorders | 2021
Risk Factors for Venous Thromboembolism after Vascular Surgery and Implications for Chemoprophylaxis Strategies.
Abstract
OBJECTIVE\nVenous thromboembolism (VTE) is an important cause of postoperative morbidity and mortality, but the reported incidence after major vascular surgery ranges from as low as 1% to upwards of 10%. Further, little is known about optimal chemoprophylaxis regimens or rates of post-discharge VTE in this population. This study aimed to better characterize in-hospital and post-discharge VTE after major vascular surgery, the role of chemoprophylaxis timing, and the association of VTE with mortality.\n\n\nMETHODS\nA single center retrospective study of 1,449 major vascular operations (2013-2020) was performed, and included 189 EVARs (13%), 169 TEVARs (12%), 318 open aortic operations (22%), 640 lower extremity bypasses (44%), and 133 femoral endarterectomies (9%). Baseline characteristics, anticoagulant/antiplatelet medications, and outcomes were abstracted from an electronic data warehouse with medical chart auditing. Post-operative VTE (pulmonary embolism [PE] and deep vein thrombosis [DVT]) within 90-days of surgery was classified based on location, symptoms, and treatment. Cut point analysis using Youden s index identified the most VTE discriminating timing of chemoprophylaxis (including therapeutic/prophylactic anticoagulant and antiplatelet medications) and Caprini score. Multivariable logistic regression tested the association of VTE with chemoprophylaxis timing, Caprini score, and additional risk factors. Cox proportional hazard modeling measured the association between VTE and mortality.\n\n\nRESULTS\nOverall VTE incidence was 3.4% (65% DVTs, 25% PEs, 10% both) and 37% were post-discharge. The rate of symptomatic VTE was 2.4%, which was lowest for EVAR (0.0%) and highest for open aortic operations (4.1%, p=0.02). Individuals who developed VTE had longer length of stay, higher rates of end-stage renal disease, prior VTE, and higher Caprini scores (8 vs 5 points) (all p<0.01). Individuals who developed VTE were also more likely to receive >2 units of blood postoperatively, have an unplanned return to the operating room, have delayed chemoprophylaxis/anticoagulation/antiplatelet initiation >4 days postoperatively, and had increased 90-day mortality (all p<0.01). Caprini score >7 (29% of patients) was associated with post-discharge VTE (2.6% vs 0.7%, p=0.01), and chemoprophylaxis/anticoagulation/antiplatelet timing >4 days was associated with increased adjusted odds of VTE (odds ratio 2.4 [1.1-4.9]). Although no fatal VTEs were identified, VTE was an independent predictor of 90-day mortality (adjusted hazard ratio 2.7 [1.3-5.9]).\n\n\nCONCLUSIONS\nThese data highlight that patients undergoing major vascular surgery are particularly prone to VTE with frequent hypercoagulable comorbidities and earlier initiation of chemoprophylaxis is associated with reduced risk of development of VTE. Furthermore, post-discharge VTE rates may reach thresholds warranting post-discharge chemoprophylaxis, particularly for patients with Caprini scores >7.