Routine BK virus surveillance in renal transplantation--a single center's experience

Abstract

Background: We started a universal screening of all our kidney transplant recipients for BK virus in 2005. This review of our experience includes patients with ≥6 months' posttransplantation follow-up.

Methods: We performed a retrospective chart evaluation of all kidney transplants from January 2005 to February 2010. Urine polymerase chain reaction (PCR) for BK virus was done on all patients starting from 4 weeks after transplantation. If negative, it was repeated monthly for the first 6 months and then every 3-4 months. If the test was positive, a urine and blood BK virus PCR done on the next visit was repeated every 2-4 weeks with a slow reduction in immunosuppression.

Results: From January 2005 to February 2010 we performed 173 kidney transplantations with 12 graft losses within the first 6 weeks which were excluded from the analysis. Induction immunosuppression consisted of anti-interleukin-2 receptor antibody (n = 102) or antithymoglobulin (ATG; n = 59). In 112 patients (70%), the urine BK virus PCR remained negative; 18 (11%) only the urine was positive and among an additional 31 (19%) BK virus PCR was positive in blood. There was no difference in incidence according to induction therapy. Delayed graft function was observed among 39 patients (24%); there was no difference in the incidence of BK virus with versus without DGF. The mean time to first detection was shorter with ATG induction (mean, 199 days; median, 90 days; range, 26-1198 days) compared with anti-IL-2 (mean, 321 days; median, 195 days; range, 23-1077 days). Urine-only positivity was first detected from 37 to 1198 days (mean, 366 days; median, 227 days) and blood positivity from 23 to 1069 days (mean, 216 days; median, 90 days). Among BK-positive patients, 26 (53%) were detected within the first 6 months and 38 (76%) within the first year. With reduction in immunosuppression, there was gradual reduction or elimination of positive PCR tests in all cases except one, which resulted in graft failure.

Conclusions: Routine BK virus surveillance is effective; it tends to detect BK virus replication early, allowing reduction of immunosuppression, which results in good outcomes with renal preservation.