Clinicopathological Correlations, Treatment Response, and Predictors of Outcomes in Childhood Lupus Nephritis in China

OBJECTIVE: To investigate clinicopathological correlations, treatment responses, and predictors of outcomes in childhood lupus nephritis (cLN). METHODS: Retrospective cohort study of 71 biopsy-proven cLN patients at Beijing Children's Hospital (2005-2024). Renal biopsies were classified per 2018 ISN/RPS criteria with activity index (AI) and chronicity index (CI) assessment. RESULTS: Over a median 40-month follow-up, 69.1% were female (mean onset age 10.0 ± 2.3 years). Proliferative LN (Class III/IV ± V) accounted for 76.0%. AI correlated with acute injury markers (creatinine, BUN, proteinuria); CI showed stronger associations with chronic tubular biomarkers but not eGFR. Complete renal remission (CRR) was achieved in 92.8% (mean 13.4 months); 26.6% experienced relapse. Failure to achieve CRR was associated with higher AI (OR = 1.738, p = 0.045), elevated SLEDAI-2K (OR = 1.339, p = 0.023), and lower C3 (OR = 0.002, p = 0.035). Higher CI predicted lower likelihood of achieving LLDAS (OR = 1.425, p = 0.042). Belimumab reduced relapse risk (OR = 0.220, p = 0.043), decreased glucocorticoid doses (8.42 vs. 16.54 mg/day, p = 0.034), and improved LLDAS (68.4% vs. 30.0%, p = 0.006) and clinical remission rates (52.6% vs. 20.0%, p = 0.016). CKD developed in 4.3%; mortality was 1.4%. CONCLUSION: Modern treatment yields favorable outcomes for cLN. Baseline disease activity, hypocomplementemia, and histological AI predict treatment response. AI and CI demonstrate distinct associations with acute and chronic injury. Belimumab offers significant advantages in relapse prevention and glucocorticoid reduction.