Monitoring of polyomavirus BK replication and impact of preemptive immunosuppression reduction in renal-transplant recipients in China: a 5-year single-center analysis.

This provides the long-term patient/graft survival and outcome of BK viremia and BK virus allograft nephropathy (BKVAN) in renal transplant recipients in the setting of intensive monitoring and preemptive of reduction of immunosuppression. Quantitative BKV DNA PCR and urinary cytology surveillance were performed regularly after transplantation in 229 kidney recipients. Patients with BK viremia and BKVAN were treated with 30-50% reduction in doses of tacrolimus and/or mycophenolate mofetil and were monitored for BKV every 3-6 months. All the patients were followed for 5 years. Overall 5-year patient and graft survival were 95.6% and 92.1%, respectively, and independent of presence of decoy cells, BK viruria, viremia, or BKVAN. After reduction of immunosuppression, BK viremia (n = 38) resolved in 100% of patients, without increased acute rejection. Recurrent BK viremia was not observed in viremic patients without BKVAN (n = 30). All BKVAN patients (n = 7, 3.1%) cleared viremia with a mean time of 5.9 months (range 1-15 months) and manifested no decline in estimated glomerular filtration rate from 1 month to 5 years after transplantation. Viral monitoring and preemptive reduction of immunosuppression resulted in the successful resolution of BK viremia and BKVAN with excellent graft survival and renal function at 5 years.