Outcome of management strategies for BK virus replication in pediatric renal transplant recipients

Management of BKV infection is not well defined. Eighteen pediatric renal transplant patients with BKV-PCR (+) were divided into three groups; Group 1: Viruria only (6), Group 2: Viremia with stable GFR (4), Group 3: Viremia with > 25% decline in GFR and BKVAN on biopsy (8). With initial BKV-PCR(+), Group 1 received no treatment; Group 2 had MMF reduced 30%; Group 3: 6/8 had CNI discontinuation, 2/8 had reduced MMF and cidofovir. BKV, GFR and histology were compared pre- and post-treatment. In Group 1 viruria decreased in all patients; GFR remained stable. Group 2 showed reduced viremia with no GFR change. Group 3 showed reduced viremia in 8/8 patients. Patients with > 50% decline in GFR from baseline (6/8) showed worse histology: 2/6 lost grafts despite no BKV on follow-up biopsy. Our results show that with viruria alone no treatment is necessary; with viremia and stable GFR, reduced immunosuppression decreases viremia and maintains GFR. With viremia and reduced GFR, immunosuppression reduction with or without cidofovir decreases viremia and stabilizes GFR in most patients. Greater than 50% reduction in GFR at BKVAN diagnosis correlates with risk for graft loss. Serial monitoring of BKV viremia with early intervention may prevent BKVAN graft loss in children.