BK viremia surveillance after kidney transplant: single-center experience during a change from cyclosporine-to lower-dose tacrolimus-based primary immunosuppression regimen.

ABSTRACT

BACKGROUND: The aim was to report our experience of BK viremia surveillance after kidney transplant during a period of change from cyclosporine (CyA)-to lower-dose tacrolimus (Tac)-based primary immunosuppression regimens. METHODS: In a prospective single-center observational cohort study, 68 consecutive patients received renal transplant during the period when we used a CyA-based primary immunosuppression regimen and 66 after we changed to a lower-dose Tac-based regimen. Testing for BK viremia by quantitative polymerase chain reaction assay was performed at least monthly for a minimum of 1 year. RESULTS: Thirty-nine (29.1%) patients developed BK viremia and 2 (1.5%) developed BK nephropathy. The actuarial time to BK viremia was shorter in patients receiving CyA/mycophenolate mofetil (MMF)/prednisolone (Pred) compared with Tac/MMF/Pred (P=0.04) and primary immunosuppression with CyA/MMF/Pred was the only independent predictor of BK viremia (hazard ratio 1.95; P=0.047). Comparing patients who experienced BK viremia and those who did not, there was no difference in incidence of acute rejection (20.5% vs. 25.3%; P=0.56) or estimated glomerular filtration rate at 12 months (48.8 vs. 49.9 mL/min/1.73 m(2)), but the incidence of ureteric stenosis was higher (10.3% vs. 1.1%; P=0.01). CONCLUSIONS: Our data demonstrate a lower incidence of BK viremia in patients on lower-dose Tac compared with CyA-based primary immunosuppression in contrast to previous studies, and provide further support for the association between BK virus and ureteric complications.