Ureteral stents: a risk factor for polyomavirus BK viremia in kidney transplant recipients undergoing protocol screening

Background: Polyomavirus BK nephropathy (BKN) remains a common cause of early renal transplant dysfunction and graft loss. To date, little has been reported on the role, if any, of transplant ureteral stents in the development of polyomavirus BK viremia (BVK) and BKN.

Methods: We performed a single-center, retrospective analysis of renal transplant recipients who underwent renal transplantation followed by monthly BKV screening at Albany Medical Center between January 1, 2006, and December 31, 2009. A transplant ureteral stent was placed at the discretion of the surgeon. The immunosuppression protocol employed for deceased donor and unrelated living -donor recipients was antithymocyte antibody induction with methylprednisolone, mycophenolate mofetil, tacrolimus, and sirolimus.

Results: During the study period, 186 recipients were identified; 124 (67%) underwent intraoperative transplant ureteral stent placement, while 62 patients (33%) did not undergo stent placement. With our monthly screening protocol, we detected BKV in 32 of the 186 recipients (17%) following transplantation; 27 of the 32 (84%) viremic patients were stent recipients. In all patients who developed BKV, an immunosuppression dose reduction protocol was employed. Ureteral stent placement conferred a statistically significant elevated risk of developing BKV (odds ratio = 3.17, 95% confidence interval 1.16-8.70). Patient gender, age, ethnicity, diabetes status, and retransplant status were not statistically significant factors in the development of BKV.

Conclusion: Our study demonstrated the elevated risk of BKV in recipients who undergo transplant ureteral stenting. Monthly BK polymerase chain reaction screening appears to be a useful tool for the early detection of BKV in this higher-risk group.