Association between serum C3 and progression of renal function in IgA nephropathy
10.3760/cma.j.cn441217-20210618-00148
- VernacularTitle:IgA肾病患者血清C3与肾功能进展的相关性分析
- Author:
Tao CAO
1
;
Ricong XU
;
Yi XU
;
Qijun WAN
Author Information
1. 深圳大学第一附属医院（深圳市第二人民医院）肾内科，深圳 518000
- Keywords:
Glomerulonephritis, IgA;
Complement C3;
Renal insufficiency;
Progression of renal function;
Smooth curve fitting
- From:
Chinese Journal of Nephrology
2021;37(12):974-979
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the relationship between serum C3 and progression of renal function in IgA nephropathy.Methods:A single-center retrospective cohort study was conducted in patients with IgA nephropathy confirmed by renal biopsy who were admitted to the Second People's Hospital of Shenzhen from January 2011 to June 2020 and the patients were followed up until January 2021. Patients with secondary IgA nephropathy, baseline estimated glomerular filtration rate (eGFR)<30 ml·min -1·(1.73 m 2) -1, lack of baseline serum C3 or creatinine, and follow-up time<6 months were excluded. The clinical data, laboratory examination and renal pathology were collected. The threshold effect analysis was used to obtain the cut-off point, and inflection point and 95% confidence interval were obtained using bootstrapping resampling technique. According to the cut-off point, the patients were divided into serum C3<0.97 g/L group and C3≥0.97 g/L group. The baseline data between the two groups were compared. Cox regression model was used to analyze the correlation between serum C3 level and renal function progression. Results:A total of 414 patients were enrolled in this study, with 145 males (35.0%), and age of (35.15±9.18) years old. The baseline eGFR was 77.80(46.67, 106.10) ml·min -1·(1.73 m 2) -1, and the serum C3 was (1.04 ± 0.19) g/L. There were 153 patients with serum C3<0.97 g/L and 261 patients with serum C3≥0.97 g/L. Compared to patients with serum C3≥0.97 g/L, those patients with serum C3<0.97 g/L were younger and had higher proportion of females, higher levels of hemoglobin and eGFR, and lower levels of mean arterial pressure, total cholesterol, triglyceride, serum uric acid, serum creatinine, 24 h urinary protein, IgA and C4 (all P<0.05). The relationship between serum C3 and progression of renal function was found to be U-shaped by smooth curve fitting. After adjustment for confounding factors such as age, sex, mean arterial pressure, serum uric acid, 24 h urinary protein, and renal pathology (MESTC), the results of the threshold effect and multivariate Cox regression showed, for patients with C3<0.97 g/L, the risk of renal function progression decreased by 40% for every 0.1 g/L increase of C3 ( HR=0.60, 95% CI 0.39-0.94, P=0.024), but for patients with C3≥0.97 g/L, every 0.1 g/L increase in serum C3 increased the risk of renal function progression by 27%( HR=1.27, 95% CI 1.03-1.57, P=0.027). The inflection point was 0.97(95% CI 0.92-1.01) g/L. Conclusions:Serum C3 is nonlinear correlated with the progression of renal function in patients with IgA nephropathy. Serum C3 level maintaining at 0.92-1.01 g/L is associated with better renal prognosis.
