Changes in serum C3d and C5b-9 levels in elderly patients with idiopathic membranous nephropathy and their clinical significance / 中华老年医学杂志

ABSTRACT

Objective:To investigate changes in serum C3d and C5b-9 levels in elderly patients with idiopathic membranous nephropathy(IMN)and their correlations with prognosis.Methods:Two hundred thirty-one elderly patients with IMN and 96 non-elderly patients with IMN confirmed by kidney biopsy at the First Affiliated Hospital of Zhengzhou University from January 2015 to May 2017 were enrolled.During the same period, 118 healthy individuals receiving health checkups were included as controls.Patients were divided into the low C3d group( n=112)and the high C3d group( n=113)according to the median level of serum C3d.Serum C3d and C5b-9 levels were measured by enzyme-linked immunosorbent assays. Results:Serum C3d and C5b-9 levels in elderly IMN patients were 0.23(0.15, 0.45)mg/L and 0.28(0.20, 1.23)mg/L, respectively, which were higher than those in healthy controls[0.18(0.13, 0.22)mg/L, 0.22(0.16, 0.26)mg/L, respectively]( Z=-4.261 and -6.213, P<0.001). Serum C3d levels in elderly and non-elderly IMN patients were correlated negatively with the estimated glomerular filtration rate( r=-0.155 and -0.426, P=0.019 and 0.000), but positively with serum creatinine, anti-phospholipase A2 receptor(PLA2R)antibody levels and 24 h urinary protein( r=0.184, 0.326, 0.407, 0.321 and 0.145, P=0.005, 0.001, 0.000, 0.001 and 0.027). Kaplan-Meier survival analysis showed that the cumulative renal survival rate in elderly IMN patients was lower in the high C3d group than in the low C3d group(47.8% vs.70.8%, Log Rank χ2=7.399, P=0.007). Multivariate Cox regression analysis showed that high C3d levels were an independent risk factor for poor renal outcomes in elderly IMN patients( HR=2.288, 95% CI 1.082-4.839, P=0.030). Conclusions:High serum C3d levels are associated with increases in urinary protein excretion and anti-PLA2R antibody levels, renal function decline, and poor renal outcomes in elderly IMN patients.