Association Between Serum IgG Concentrations and Prognosis in IgA Nephropathy

Abstract

Introduction. To investigate the relationship between serum IgG (sIgG) concentration and the prognosis of IgA nephropathy (IgAN). Methods. A total of 309 patients with biopsy-proven IgAN in the Second Referral Hospital of Shenzhen were enrolled between 2010/01 and 2017/06. Patients were divided into 3 groups on the basis of sIgG tertiles: < 8.99 g/L (Group G1), 8.99 to 11.17 g/L (Group G2), and > 11.17 g/L (Group G3). Results. As the level of sIgG increased, there was a decrease in DBP, serum creatinine, 24h urine proteinuria and an increase in serum albumin (all P < .05). In terms of pathological manifestations, with increasing sIgG levels, there was a tendency of decline in the Lee’s grading system or high-grade tubular atrophy/interstitial fibrosis or in the proportion of glomerular sclerosis and the ratio of crescent (all P < .05). Kaplan-Meier analysis indicated that the cumulative renal survivals rates were significantly higher in patients with elevated sIgG (P < .05). Cox regression analysis showed that after adjusting for gender, age, BMI, and clinical indicators (BP, 24h urine proteinuria, eGFR, M, E, S, T, and the ratio of crescent), decreased sIgG level at the time of renal biopsy is an independent risk factor for unfavorable outcomes in IgAN. Furthmore, every 1 g/L decrease in sIgG level was associated with a 1.74-fold (95% CI: 1.30 to 5.38) increased risk of the incidence of composite renal outcomes. Conclusions. Decreased serum IgG level at baseline might be a kind of predictive marker for the poor prognosis of IgAN.