Association Between Serum IgG Concentrations and Prognosis in IgA Nephropathy

Abstract Objective: This study was aimed to assess the relationship between serum IgG (SIgG) level and the clinical, pathological phenotype of IgA nephropathy (IgAN), and to determine the role of SIgG level in the progression and prognosis of IgAN. Methods : It was a multi-center retrospective cohort study, patients with biopsy proven primary IgAN who were recorded in the Chinese IgA Nephropathy Information Registration System between April 1996 and September 2018 were included. Patients were divided into 3 groups according to the baseline tertiles of sIgG : ≤9.50g/L, 9.51 to 11.99 g/L, and≥ 12.00 g/L. The endpoint events were defined as doubled serum creatinine level from baseline, or end-stage renal disease (ESRD). Results: A total of 1976 IgAN patients were included in this study. At baseline, mean age, eGFR, and serum IgG levels were 34.84 ± 10.75years, 80.38 ± 33.09mL/min/1.73 m2, and 10.82 ± 3.23g/L, respectively. During a median of  33months of follow-up, endpoint events were observed in 232 (11.74%) patients. After adjustment for demographic and IgAN-specific covariates and treatments, patients with a higher tertile of SIgG was associated with an decreased risk of developing poor renal outcomes from the Cox proportional hazards models. Conclusion: The higher level of sIgG at diagnosis is associated with better clinicopathologic features and renal outcomes, and may portend better renal survival in IgAN patients.