Renal Outcomes in Survivors of Neonatal and Pediatric Renal Vein Thrombosis

Introduction: Pediatric renal vein thrombosis is a rare but well-recognized form of venous thromboembolism. While long-term renal outcomes of neonatal cases are well-described, they are relatively unknown in cases affecting older children. Moreover, the ability of anticoagulation treatment to prevent these outcomes remains unknown. The objective of this study was to assess adverse long-term renal outcomes and determine if anticoagulation reduced their likelihood. Methods: Administrative data analysis utilizing the Pediatric Health Information System database. Renal vein thrombosis occurring in patients under 18 years were assessed. Cases involving tumor thrombus were excluded to focus the analysis only on thrombotic disease. Demographics, co-morbid conditions, anticoagulant therapies, and renal outcomes were assessed over a 9-year period. In sub-analyses, neonatal ([≤]28 days) and non-neonatal renal vein thromboses were assessed to determine how their characteristics may differ. Results: 383 eligible renal vein thrombosis cases with 796 patient-years of follow-up were identified for analysis. 48.8% of the cases occurred in neonates. 25.3% of the cases occurred in children with pre-existing complex chronic conditions and 9.1% were associated with the onset of nephrotic syndrome. Mortality followed 15.1% of the cases, but causality cannot be assigned from administrative data. Most (80.2%) of the cases were treated with anticoagulation. Acute kidney injury occurred in 24% of cases, chronic kidney disease developed in 22.2%, hypertension in 26.9%, and proteinuria in 3.1%. Anticoagulation did not have a discernable effect on the likelihood of these long-term renal outcomes. Conclusion: Acute kidney injury, chronic kidney disease, and hypertension are prevalent in survivors of childhood renal vein thrombosis. Anticoagulation does not appear to reduce the incidence of long-term renal outcomes, but the low percentage of non-anticoagulated patients suggests treatment bias. Long-term kidney health surveillance is warranted in pediatric renal vein thrombosis survivors.