Longitudinal changes in proteinuria and kidney function during standard-dose Nefecon treatment in IgA nephropathy: A real-world cohort study

BACKGROUND: Real-world evidence regarding longitudinal changes in proteinuria and kidney function during standard-dose Nefecon treatment in IgA nephropathy remains limited. This study evaluated longitudinal changes in proteinuria, kidney function, and safety during Nefecon 16 mg/day treatment in routine clinical practice. MATERIALS AND METHODS: This retrospective cohort study screened 256 patients with IgA nephropathy treated with Nefecon. Patients receiving standard-dose Nefecon 16 mg/day for at least 3 months with available baseline and follow-up efficacy data were included. Only measurements obtained during standard-dose treatment were analyzed. Longitudinal changes in natural logarithm-transformed urine protein-to-creatinine ratio (lnUPCR) and estimated glomerular filtration rate (eGFR) were evaluated using linear mixed-effects models adjusted for age, sex, baseline lnUPCR, baseline eGFR, and time-updated renin-angiotensin system (RAS) inhibitor and sodium-glucose cotransporter 2 (SGLT2) inhibitor use. Compared with baseline, lnUPCR was significantly lower at 3 months (β = -0.337, 95% confidence interval (CI): -0.483 to -0.191), 6 months (β = -0.426, 95% CI: -0.614 to -0.237), and 9 months (β = -0.451, 95% CI: -0.680 to -0.221; all p < 0.001). Piecewise analysis showed that UPCR declined most rapidly during the first 3 months. eGFR was significantly higher at 3 and 6 months and remained numerically higher at 9 months. Baseline proteinuria significantly modified the lnUPCR trajectory. 32 patients (25.6%) experienced at least 1 adverse event. CONCLUSION: Patients receiving standard-dose Nefecon showed a significant reduction in proteinuria over time, mainly during the first 3 months. Further controlled studies with longer follow-up are needed to determine whether this early reduction is associated with long-term kidney function benefit.