Risk of Thromboembolism in Hospitalized Children with Nephrotic Syndrome

Background: Thromboembolism (TE) is a complication of nephrotic syndrome (NS) that requires prolonged anticoagulation and can lead to significant health consequences. NS increases TE risk due to urinary anticoagulant loss, increased procoagulants, and thrombocytosis. TE incidence, risk factors, and hospitalization characteristics were evaluated in the Pediatric Health Information System (PHIS) database. Methods: A retrospective cohort study was performed among children ≤19 years hospitalized at 31 PHIS centers between 1/1/2009-12/31/2024 with NS diagnosis. NS and TE were identified using previously validated ICD 9/10 code sets and requirement of anticoagulant prescription for TE. Exclusion criteria included systemic lupus, connective tissue disease, obstructive uropathy, glomerulonephritis, and malignancy. Encounters for patients with TE within the prior 3 months were also excluded. Generalized estimating equation regression was used to examine associations between potential risk factors and TE. Results: TE occurred in 472 of 29,513 hospital encounters (1.6%) and 403 of 10,864 patients (3.7%) with NS. Patients with TE encounters were older (median age 11 vs. 8, p<0.001). Odds of TE were higher in encounters with central line, surgery, history of prior TE, infection, and edema management (Figure 1, p=0.001-0.04). Common TE locations included upper extremity (41.5%), pulmonary (19.5%), lower extremity (11.5%), intracranial (10.6%) and renal (7.8%). Common treatments included enoxaparin (68.4%), heparin (66.9%), warfarin (14.4%), rivaroxaban (5.1%), and thrombolysis (3.2%). TE was associated with longer hospital stay (10 days vs. 2 days, p<0.001), greater need for ICU-level care (50.4% vs. 8%, p<0.001), and higher mortality (5.7% vs. 0.4%, p<0.001). Conclusion: Nearly 4% of hospitalized children with NS experienced TE, with significant associated morbidity and mortality. Identifying risk factors can provide potential opportunities for thromboprophylaxis. Funding: Other NIH Support - Philadelphia Program for Mentored Research Training in Kidney, Urologic, and Hematologic Diseases (PERFORM-KUH U2C/Tl1): Grant# U2CDK136784Figure 1