C3 and chronic kidney disease: Meanwhile, patients with > 2+ glomerular C3 deposition showed a faster mean decline rate of eGFR than those with ≤ 2+ glomerular C3 deposition [− 0.3 (− 0.9– − 0.1) vs. − 0.1 (− 0.5–1.2), P < 0.001], indicating the important role of complement on the progression of renal function in IgAN patients with stage 4 CKD.