Clinicopathological characteristics and outcomes of adult patients with idiopathic membranoproliferative glomerulonephritis according to an immunofluorescence-based classification

The classification of membranoproliferative glomerulonephritis (MPGN) into immune complex-mediated MPGN and complement-mediated MPGN on immunofluorescence has provided insights into two distinct disease processes. There are limited data available on renal outcomes of MPGN from developing countries.

A retrospective analysis was conducted on biopsy-proven MPGN cases diagnosed between 1998 and 2018 at the Sindh Institute of Urology and Transplantation (SIUT). Secondary causes were excluded. Patients were reclassified as immune complex-mediated-MPGN and complement-mediated-MPGN based on immunofluorescence results. The clinicopathological findings and outcomes of the two groups were compared.

In total, 213 patients with idiopathic MPGN were identified. Among these, 163 (76.5%) were reclassified as immune complex-mediated-MPGN and 50 (23.4%) as complement-mediated-MPGN. No significant differences were found between the two groups regarding age, gender, clinical characteristics, biopsy indications, biopsy findings, and renal function at presentation. Overall, 63 subjects (38.7%) with immune complex-mediated-MPGN and 27 (54%) with complement-mediated-MPGN received immunosuppressive agents (p = 0.08). Complete and partial remission rates were higher in immune complex-mediated-MPGN than in complement-mediated-MPGN (76% vs 58%, p < 0.05). At two years, median estimated glomerualr filtration rate (eGFR) tended to be higher in patients with immune complex-mediated-MPGN 91.2 (45.4–113.7) vs 83.45(34.6–102.50) ml/min/1.73 m², p = 0.22) with significantly better renal survival (76% vs 58%, p = 0.03). Comparatively, more patients progressed to end-stage kidney disease (ESKD) in the complement-mediated-MPGN group (32% vs 19.6%, p = 0.06), with increased overall mortality (5 (10%) vs 7 (4.3%), p = 0.12).

The clinicopathological features at presentation of complement-mediated-MPGN are similar to those of immune complex-mediated-MPGN. However, it is less frequent and overall prognosis is less favorable.