Perception, diagnosis and management of BK polyomavirus replication and disease in paediatric kidney transplant recipients in Europe

BK polyomavirus (BKPyV)-associated nephropathy remains a challenge to the success of kidney transplantation, but its impact varies in different transplant programmes. We investigated current practice through a web-based questionnaire made available by the European Society for Paediatric Nephrology (ESPN). A total of 90 physicians (23% of 391 active members) from 27 countries participated in the study. BKPyV-associated nephropathy is seen in 1-5% of patients annually with treatment success in 30-60%, and graft loss in 10%. Quantitative BKPyV load testing is available to > 90% of physicians. Screening is performed in urine alone in 26%, in urine and blood in 37% and in blood alone in 37%. Most physicians (47%) screen at month 1, 2, 3, 6, 9 and 12 post-transplant. For patients with baseline renal function and plasma BKPyV loads of 10 000-1 000 000 copies/mL, 50% report performing renal biopsies prior to intervention. Intervention consists of reducing immunosuppression first with mycophenolate (Myc) in 40%, first with calcineurin inhibitors (CNI) in 29% or with both in 31%. Changing immunosuppressive drugs is considered mainly for biopsy-proven nephropathy consisting of discontinuation of Myc in 75%, and switching from CNI to mTOR inhibitors (52%). Cidofovir, intravenous immunoglobulin G, leflunomide and fluoroquinolones are used in less than one-third of this group. Furthermore, 66% of participants see a need for new antiviral drugs and new immmunosuppressive strategies, and almost 90% are willing to participate in future observational and interventional trials. This ESPN survey suggests that prompt translation of a positive screening test into reducing immunosuppression could improve outcomes.