Comparing urine and blood screening methods to detect BK virus after renal transplant

Objectives: BK polyomavirus can infect healthy individuals; however, in renal transplant recipients, it can cause nephropathy, which can lead to renal allograft failure. There are currently no effective antiviral agents against BK polyomavirus. Surveillance after kidney transplant for BK polyomavirus is the only means to prevent allograft failure. Transplant centers routinely screen for BK polyomavirus in either urine or blood. If BK polyomavirus replication occurs, it is usually detected first in urine, which is followed by detection in blood in a subset of cases. Screening for BK polyomavirus in urine has the potential for earlier detection of viral reactivation. However, not all patients with BK polyomavirus in urine will progress to BK viremia. Therefore, adding urine screening could increase the cost of tests without a clear clinical benefit. Materials and Methods: We conducted an analysis of BK polyomavirus screening methods at 2 different centers and compared their clinical outcomes and efficiency of testing. Results: We analyzed 209 patients with BK polyomavirus reactivation after kidney transplant at 2 different institutions from 2008 to 2018. BK polyomavirus reactivation in blood was detected earlier if the patient was screened by urine screening protocol. However, measurable clinical outcomes were similar in all groups with different screening methods. Conclusions: Although screening for BK polyomavirus in urine did detect viral reactivation earlier, there were no differences in graft or clinical outcomes when either the urine or blood screening method was used.