Does reduction in immunosuppression in viremic patients prevent BK virus nephropathy in De Novo renal transplant recipients?: A prospective study

Background. BK virus nephropathy (BKVN) is a severe complication of renal transplantation, resulting in graft loss in > 50% of cases. Because patients with BKV viremia are at high risk for developing BKVN, the aim of our study was to analyze whether early reduction of immunosuppression (IS) could prevent BKVN in viremic patients. Methods. BKV viruria was prospectively screened every 3 months by real-time polymerase, chain reaction during the first year after transplantation in 123 consecutive renal transplant recipients. Plasma viral load was measured by polymerase chain reaction whenever viruria was positive; in viremic patients a graft biopsy was systematically performed and IS was reduced. Results. Viruria, viremia, and BKVN occurred in 48.8%, 10.5%, and 2.4% of patients, respectively. In the 13 patients with positive viremia, initial graft biopsy showed BKVN in two. After reduction of IS in patients without BKVN, viremia disappeared in 8 of 11, decreased in 2 of 11, and increased in one patient who eventually developed BKVN. In contrast, viremia remained positive in one patient with BKVN and disappeared in the second but renal function deteriorated in both of them. Initial viral load was higher in patients who developed BKVN. Conclusion. Reduction of IS is probably an effective therapeutic option to clear viremia and prevent BKVN in viremic renal transplant patients.