Comparison of real-world kidney outcomes with predicted outcomes at the time of diagnosis and post-biopsy in a cohort of children with IgA nephropathy.

Introduction: IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis, with a variable clinical course. This study aimed to evaluate real-world kidney outcomes in children with IgAN and compare these with predictions from the International IgAN Prediction Tool for children (IIgAN-PT).

Methods: A single-center, longitudinal retrospective study was conducted on pediatric patients diagnosed with IgAN from 2010 to 2022. Data on clinical, laboratory, and histological parameters were analyzed. The IIgAN-PT score was calculated for each patient at biopsy and one year after biopsy. The primary outcome was a composite endpoint of ≥30% eGFR decrease or progression to end stage kidney disease (ESKD).

Results: Among 23 patients (57% male, median age at biopsy 13.8 years), MEST-C scores showed M1 in 87%, E1 in 22%, S1 in 39%, T1/2 in 13%, and C1 in 26%. During a median 3.1-year follow-up, 26% reached the primary outcome, while the median predicted risk based on IIgAN-PT was 6.5%. Additionally, 57% experienced eGFR decline (annual median decline of 5.6 mL/min/1.73 m2). Application of the updated IIgAN-PT one-year post-biopsy (n = 13) resulted in a median predicted risk of 1.79%, while 23% met the primary outcome.

Conclusion: The observed eGFR decline or progression to ESKD was higher than predicted, highlighting the need for early diagnosis, monitoring, and treatment. Small-scale studies like ours underscore the importance of early intervention and may inform the design of larger studies to improve the predictive ability of the IIgAN-PT tool in diverse clinical settings.