Screening for polyomavirus nephropathy and viremia in children with renal transplantation.

BACKGROUND: Polyomavirus, known as BK virus, is an important cause of allograft dysfunction in renal transplant patients, leading to BK virus nephropathy. The main study objectives were to assess the disease incidence and disease course in pediatric patients, and assess the diagnostic accuracy of BK screening for asymptomatic patients. METHODS: This is a single-center observational study, which included 81 pediatric renal allograft recipients that were transplanted and/or followed at King Fahad Specialist Hospital-Dammam, Saudi Arabia. Screening for BK virus was performed prospectively according to a predetermined hospital protocol. Our BK screening protocol consisted of periodic quantitative real time polymerase chain reaction test in the plasma. In patients with deranged graft function, graft biopsies were evaluated for the presence of BK nephropathy. RESULTS: Our study detected BK viremia in 14 patients (17.3%), while BK nephropathy occurred in seven patients (8.6%). The onset of BK viremia had bimodal distribution, 78 percent occurring within first year post-transplantation, while 21.4% occurred late. Patients who developed BK nephropathy had a higher BK level than BK viremia patients, for both mean and peak values (p = .02, p = .02). A BK cutoff level of 40 000 copies/mL showed sensitivity and specificity of 85.7%, 85.7%, respectively, in predicting the conversion of BK viremia to BK nephropathy. CONCLUSIONS: BK viremia and BK nephropathy occur in pediatric patients with similar incidence rates compared to adult patients. Protocolized screening led to early detection of viremia, and could predict the conversion of BK viremia to BK nephropathy and allow for early immunosuppression modulation.