Correlation between complement C3 level and abdominal aortic calcification in non-dialysis chronic kidney disease patients: a cross-sectional study

Background Previous studies have shown that complement activation is associated with an increased risk of cardiovascular disease in patients with chronic kidney disease (CKD) on dialysis. This study aims to investigate the relationship between complement 3 (C3) and vascular calcification (VC) in non-dialysis-dependent CKD (NDD-CKD) patients. Methods Four hundred and fifty six NDD-CKD patients were enrolled from 2019 to 2022. C3 was measured by immunoscattering turbidimetry. According to the results of CT imaging, the patients were divided into the aorta vascular calcification group and the non-aortic vascular calcification group. Restricted cubic spline (RCS) analysis and logistic regression model were used to explore the association between C3 and VC in NDD-CKD patients. To assess how it predicted, a receiver operating characteristic (ROC) analysis was undertaken. Results In NDD-CKD patients, the third tertile of C3 (0.95–1.63 g/L) was significantly correlated with VC (OR = 2.06, 95% CI: 1.13–3.83, p = 0.020). Older age and history of underlying diseases (hypertension, hyperlipidemia) are independent risk factors for VC in NDD-CKD patients. The area under the curve (AUC) of C3 for predicting VC was 0.849 g/L (sensitivity, 79.4%; specificity, 76.7%). Conclusion In patients with NDD-CKD, serum complement C3 exhibits a J-shaped relationship with vascular calcification, indicating a complex, non-linear association. Additionally, older age, hypertension, and hyperlipidemia were confirmed as independent risk factors.