554 - Characterization of infection outcomes and temporal trends over 15 years in hospitalized children with nephrotic syndrome within the Pediatric Health Information System (PHIS)

Publication Number: 4542.554

Sonya R. Kowalczyk, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Tran Bourgeois, Children's Hospital of Philadelphia, Philadelphia, PA, United States; Jarcy Zee, Childrens Hospital of Philadelphia, Philadelphia, PA, United States; Madhura Pradhan, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States; Michelle Denburg, Children's Hospital of Philadelphia, Philadelphia, PA, United States

Background: Infection is a major, life-threatening complication in children with nephrotic syndrome (NS). While significant efforts have focused on decreasing serious infections in NS through improved immunization strategies (PCV and influenza vaccines), studies characterizing infection in this population are small and of short duration. To better define infection risk factors, associated outcomes, and temporal trends, we conducted a retrospective cohort study of pediatric NS hospitalizations over 15 years using the Pediatric Health Information System (PHIS) database.

Objective: To characterize infection incidence, characteristics, risk factors, outcomes, and temporal trends in hospitalized pediatric patients with NS over 15 years.

Design/Methods: We conducted a retrospective cohort study of children ≤21 years with NS diagnosis hospitalized at 31 PHIS centers between 1/1/2009 and 12/31/2024. NS and infection were identified using validated ICD 9/10 code sets with requirement of anti-microbial prescription for infection. Exclusion criteria included malignancy or solid organ transplant. Descriptive statistics were performed. Generalized Estimating Equations were used to examine associations between potential risk factors and infection and to assess change in infection incidence over time.

Results: Infection was identified in 6,160/ 30,214 hospitalization encounters (20.4%) and in 3,451/10,790 patients (32.0%) with NS. Among encounters with infection, the most common sites were central nervous system (25.0%), lower respiratory tract (20.1%), peritoneum (15.8%), and skin/soft tissue (8.6%). Influenza was diagnosed in 2.3% of admissions. Independent risk factors for infection included age, gender, central line, surgery, and prescription of steroid-sparing immunosuppressives (Figure 1). Compared to encounters without infection, those with infection were associated with longer hospital stays (4 vs 2 days, p< 0.001), increased ICU level care (21.3% vs 5.2%, p< 0.001), and higher mortality (1.4% vs 0.2%, p< 0.001) (Table 1). Incidence rate of overall infection, peritonitis, CNS infection, and influenza decreased over the 15 years, while rate of pneumonia increased (Figure 2).

Conclusion(s): Infection is a major complication in hospitalized children with NS, occurring in one-fifth of encounters and associated with substantial increases in morbidity and mortality. The observed decrease in certain serious infections , including CNS infections, peritonitis, and influenza, suggests a potential impact of the expanded pneumococcal coverage of vaccines and improvements in clinical management guidelines and preventive care over time.

Table 1. Baseline inpatient demographic and clinical characteristics and encounter outcomes by infection status
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Figure 1. Association of hospitalization encounter characteristics with infection


Figure 2. Incidence of infection subtypes across hospitalization encounters between 2009-2024.