512 - Low Serum IgG Levels at Disease Onset Predict Nephritis Development in Children with IgA Vasculitis

Publication Number: 2497.512

Yuna Hiwatari, The Jikei University School of Medicine, Tokyo, Tokyo, Japan; Daishi Hirano, The Jikei university school of medicine, Ohta-ku, Tokyo, Japan; Aya Saito, Department of Pediatrics, The Jikei University School of Medicine, Tokyo, Japan, Minato-ku, Tokyo, Japan; Akira Ito, The Jikei University School of Medicine,, Atsugi, Kanagawa, Japan; Saori Miwa, The Jikei University School of Medicine, Tokyo, Tokyo, Japan; Chisato Umeda, Department of Pediatrics, the Jikei University School of Medicine, Minato-ku, Tokyo, Japan; Haruhide Sakaguchi, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan; Yosuke Shoji, Pediatrics, Huchu, Tokyo, Japan; Shiho Yoshizawa, The Jikei University School of Medicine, Taito-Ku, Tokyo, Japan; Yoichi Takemasa, Department of Pediatrics, The Jikei University School of Medicine,, yokohama, Kanagawa, Japan; Kimihiko Oishi, The Jikei University School of Medicine, MInato-ku, Tokyo, Japan

Background: IgA vasculitis (IgAV), formerly known as Henoch-Schönlein purpura, is the most common systemic vasculitis in children and is characterized by palpable purpura, arthritis, and abdominal pain. Although IgAV is often self-limiting, nephritis develops in 30-60% of cases and largely determines long-term outcomes. Early identification of patients at risk for renal involvement is crucial to prevent progression to end-stage renal disease. However, clinical predictors of nephritis have not yet been clearly established.

Objective: To identify clinical and laboratory factors associated with the development of nephritis within six months after disease onset in children with IgAV.

Design/Methods: This retrospective cohort study included children aged ≤15 years diagnosed with IgAV at The Jikei University School of Medicine, Japan, between January 2018 and January 2024. Diagnosis was based on the American College of Rheumatology and European League Against Rheumatism criteria. Nephritis was defined as hematuria with >5 RBCs/HPF on urinalysis within six months after disease onset. Variables analyzed included demographics, clinical manifestations, prednisolone use, and laboratory data. Univariate and multivariate logistic regression analyses were conducted.

Results: Seventy-five children with IgAV were identified (33 males, 44%, median age, 5.5 years). Fourteen patients (18%) developed nephritis within six months after disease onset. Univariate analysis showed no significant differences in sex, duration of purpura, blood pressure, C-reactive protein, or fibrin degradation product levels. However, patients who developed nephritis had significantly higher rates of prednisolone use (P=0.013) and lower serum IgG levels at onset (P=0.0057). Age at onset tended to be higher in nephritis cases (P=0.097). Multivariate analysis confirmed that low serum IgG levels at onset independently predicted the development of nephritis (P=0.024).

Conclusion(s): Low serum IgG levels at disease onset independently predicted the development of nephritis within six months in children with IgAV. Serum IgG levels at disease onset may serve as a simple, useful biomarker for early risk stratification.

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