Significance of asymptomatic persistent epstein-barr viral load in pediatric renal transplant recipients: North American pediatric renal trials and collaborative studies report

Background: Many pediatric transplant (TX) centers routinely monitor Epstein-Barr (EB) viral load (VL) by real time quantitative PCR and intervene to prevent post-transplant lymphoproliferative disorder (PTLD). Some children develop asymptomatic persistent VL (PVL). Outcome of different interventions in preventing PTLD and other undesired effects on acute rejection (AR), graft failure (GF) and function amongst children with asymptomatic PVL is not known. Methods: NAPRTCS centers invited to enter data on children with asymptomatic PVL (≥ 6 months) into the EB VL registry. Comparison group included children into the NAPRTCS TX arm during the same period without PVL or VL monitoring. EB VL were arbitrarily divided into low (1-10), medium (>10-100) and high (>100times detection limit for the center) ratio. Results: Of 645 children (18 centers), 85 (13.2%) developed onset of PVL at a mean of 6.4 ± 6.3 months post-TX. PVL children were more likely to be younger (< 5 years) at TX and less likely to be African-American and majority (75.3%) was mismatched for EBV (donor EBV IgG positive and recipient negative). Thymoglobulin induction was used in 29.4% children with PVL versus 37% in controls (p=ns). PTLD developed in 7/85 (8.2%) children with PVL versus 5/560 (0.9%) controls (p < 0.0001). EB VL ratios were not different in those with and without PTLD. EB PVL as time varying covariate did not affect patient survival, GF and AR (HR, 0.85, 0.53 and 0.99). The change in GFR overtime in children with PVL was comparable to controls. Conclusion: Children with PVL (actual load not predictive) are at increased risk for PTLD, but not for AR, death, GF or loss of graft function.