Purpose: BK virus (BKV) nephropathy has increasingly become an important cause of morbidity in renal transplant recipients. We evaluated the frequency and associated factors for BKV infection in a center performing mainly living donor transplantations over a long time period.
Methods: One hundred consecutive renal transplant patients were included. Quarterly visits were planned to examine urine for decoy cells and to measure the BKV DNA in the blood and urine. Renal biopsy was performed in case of deteriorated allograft function. Serological examinations for BKV immunoglobulin G (IgG) were performed in donors.
Results: Throughout the entire follow-up period, the rates of viruria, viremia, and the positivity of decoy cells were 12%, 6%, and 13%, respectively. The negative and positive predictive values of decoy cells were 93.1% and 69.2%, respectively, for viruria, and 99.2% and 45.5%, respectively, for viremia. Biopsy-proven BKV nephropathy was observed in 1 patient. The BKV IgG was positive in all living donors. Viruria and viremia were associated with deceased donor transplantation, acute rejection, and pulse steroid therapy. In addition, viremia was associated with antithymocyte globulin therapy and a short duration of the posttransplant period.
Conclusions: The frequency of BKV infection was lower in our transplant unit compared to previous reports. Reduced doses of immunosuppression seem to be the main factor that may explain the reduced frequency. However, an active screening strategy is still of importance for this patient group.
Keywords: BK virus; immunosuppression; living donor; nephropathy; renal transplantation.