Incidence of Thromboembolic Complications Following Kidney Transplantation with Short and Extended Aspirin Prophylaxis: A Retrospective Single-Center Study

BACKGROUND Aspirin prophylaxis has been associated with reduced graft-related thrombosis following kidney transplantation. Aspirin cessation, however, can increase risk of venous thromboembolic complications, including pulmonary thromboembolism and deep venous thrombosis. This single-center, retrospective, pre-post interventional study from Brisbane, Australia, aimed to compare the rate of thrombotic complications in 1208 adult kidney transplant recipients receiving postoperative aspirin for 5 days or >6 weeks. MATERIAL AND METHODS We enrolled1208 kidney transplant recipients who received 100 mg aspirin for 5 days (n=571) or >6 weeks (n=637) postoperatively. The primary outcome was venous thromboembolism (VTE) in the first 6 weeks after transplant, examined by multivariable logistic regression analysis. Secondary outcomes were renal vein/artery thrombosis, 1-month serum creatinine, rejection, myocardial infarction, stroke, blood transfusion, dialysis at day 5 and day 28, and mortality. RESULTS Sixteen (1.3%) patients experienced VTE (5-day n=8, 1.4%; >6-week n=8, 1.3%; P=0.8). Extended aspirin duration was not independently associated with a reduction in VTE (OR 0.91, 95% CI 0.32-2.57; P=0.9). Graft thrombosis was rare (n=3, 0.25%). Aspirin duration was not associated with cardiovascular events, blood transfusion, graft thrombosis, graft dysfunction, rejection, or mortality. VTE was independently associated with older age (OR 1.09, 95% CI 1.04-1.16; P=0.002), smoking (OR 3.59, 95% CI 1.20-13.2; P=0.032), younger donor age (OR 0.96, 95% CI 0.93-1.00; P=0.036), and thymoglobulin use (OR 10.5, 95% CI 3.09-32.1; P≥0.001). CONCLUSIONS Extended-duration aspirin use did not significantly reduce the incidence of VTE in the first 6 weeks following kidney transplantation. An association was identified between anti-human thymocyte immunoglobulin and VTE, which requires further assessment.