Sirolimus does not increase the risk for postoperative thromboembolic events among renal transplant recipients

Background. Deep venous thrombosis (DVT) tends to occur in greater frequency among cyclosporine (CsA)-treated renal-transplant recipients. Because administration of sirolimus may increase the whole-blood concentrations of CsA, we sought to assess the impact of the combination regimen on the incidence, predisposing factors, and consequences of postoperative DVT, transplant renal-vein or artery thrombosis, and pulmonary embolus. Methods. We retrospectively evaluated two cohorts of renal transplant recipients: CsA/prednisone (Pred) azathioprine (n=136, group A) or sirolimus+CsA+Pred (n=354, group B) using Fisher's exact t and chi-square tests, as well as Kaplan-Meier analyses, odds ratios, and multiple logistic regression methods. Results. The 7 of 136 (5.1%) incidence of thrombotic events in group A was similar to the 20 of 354 (5.6%) incidence in group B (P=0.513; NS) and occurred no more frequently ipsilateral to the transplant. Although the occurrence of an acute-rejection episode was not associated with the DVT diagnosis, all affected patients displayed elevated serum creatinine (Scr) values, which remained slightly higher than baseline following recovery (group A 1.63+/-1.22-1.95+/-0.93 mg/dL; group B 1.70+/-1.11-2.01+/-0.88 mg/dL). Renal biopsies failed to show evidence of intrarenal coagulopathy. No patient lost a graft as a complication of DVT, nor did these events produce other lasting adverse effects. Patients in the sirolimus group showed a strong correlation between the occurrence of DVT and the previous existence of an ipsilateral or contralateral lymphocele. Conclusion. Addition of sirolimus to a CsA+Pred regimen does not increase the incidence of postoperative thrombotic events among renal transplant recipients.