Clinical features and outcomes of immune complex-membranoproliferative glomerulonephritis and C3 glomerulopathy: a multicenter observational cohort study analyzing kidney biopsy cases

초록

Membranoproliferative glomerulonephritis (MPGN) has two subtypes based on immunofluorescence findings: complement 3 glomerulopathy (C3G) and immune complex-mediated MPGN (IC-MPGN). This study investigated the characteristics and prognosis of patients with MPGN. This retrospective study analyzed data from 18 hospitals between 1979 and 2018. Among 21,697 patients, 620 were diagnosed with MPGN, 570 with IC-MPGN, and 50 with C3G. The C3G group had a lower estimated glomerular filtration rate (eGFR; 49.9 &#xb1; 40.7 mL/min/1.73 m2 vs. 62.7 &#xb1; 36.5 mL/min/1.73 m2, p = 0.02) compared with the IC-MPGN group. This trend continued at 6 months: patients with reduced renal function were 36.7% in the C3G group (p = 0.11). However, the IC-MPGN group had significantly higher levels of proteinuria (4.7 &#xb1; 4.2 g/g vs. 2.9 &#xb1; 2.6 g/g, p < 0.001). The 50.7% of patients with IC-MPGN had nephrotic-range proteinuria. Serum C3 levels were significantly lower in the C3G group (p = 0.04). Hepatitis B surface antigen positivity was significantly more frequent in the IC-MPGN group (35.3% vs. 7.0%, p < 0.001). Interstitial fibrosis and tubular atrophy, markers of chronic kidney damage, were more prevalent in the IC-MPGN group (p &#x2264; 0.001). During a follow-up period of 122.4 &#xb1; 124.2 months, a total of 159 patients (27.7%) with MPGN progressed to end-stage kidney disease (ESKD): 151 IC-MPGN (28.4%) and eight C3G patients (19.0%) (p = 0.28). The adjusted risk of 40% eGFR decline, ESKD, and mortality was not different between groups. The C3G group initially showed severe renal dysfunction. Despite having fewer chronic histological findings, the long-term renal outcomes for C3G remained as unfavorable as those for IC-MPGN. This suggests that C3G may require careful monitoring and treatment.

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