Table 1.
Comparison of demographics, disease-related characteristics, and histopathological parameters of patients with pauci-immune glomerulonephritis with low or normal serum C3 complement at diagnosis
| Characteristic | Normal C3 n = 91 | Low C3 n = 24 | P value |
|---|---|---|---|
| Patients | 91 (79.1%) | 24 (20.1%) | |
| Sex, male | 46 (50.5) | 14 (58.3) | 0.49 |
| Race, Caucasian | 88 (96.7) | 23 (95.8) | 1 |
| Age, yr | 56.8 (17.5) | 57.6 (17.5) | 0.82 |
| ANCA type | |||
| Negative | 5 (5.5) | 2 (8.3) | 0.69 |
| C/ PR3-ANCA | 30 (30) | 9 (37.5) | |
| P/MPO-ANCA | 56 (61.5) | 13 (54.2) | |
| Clinical phenotype | |||
| Renal limited disease | 29 (31.8) | 11 (45.8) | 0.46 |
| Granulomatosis with polyangiitis | 22(24.2) | 4(16.7) | |
| Microscopic polyangiitis | 40 (44) | 9 (37.5) | |
| Oliguria | 35 (38.5) | 12 (50) | 0.30 |
| Acute dialysis requirement | 20 (22) | 13 (54.2) | < 0.01 |
| Serum creatinine, mg/dl | 3.5 (2.2) | 5.3 (3.4) | <0.01 |
| Estimated GFR, ml/min/1.73 m2 | 24.7 (22.8) | 18.3(15.0) | 0.11 |
| Peak serum creatinine, mg/dl | 4.5 (2.7) | 6.4 (3.5) | 0.02 |
| BVAS score | 17.4 (5.7) | 17.5 (6.2) | 0.83 |
| Immunosuppressive therapy (initial) | |||
| Cyclophosphamide + glucocorticoids | 91(100) | 24 (100) | |
| Plasma exchange | 21 (29.6) | 9 (37.5) | 0.45 |
| Rituximab | 18 (19.7) | 7 (29.2) | 0.25 |
| Histopathological parameters | |||
| Normal glomeruli (%) | N=85 | N=24 | 0.51 |
| Grade 1, >50% | 12 (14.1) | 3 (12.5) | |
| Grade 2, 25%–50% | 21 (24.7) | 9 (37.5) | |
| Grade 3, 10%–24% | 22 (25.8) | 9 (37.5) | |
| Grade 4 <10% | 30 (35.3) | 8 (33.3) | |
| Normal glomeruli (>10%) | 55 (64.7) | 16 (66.7) | 0.8 |
| EUVAS categories | 0.5 | ||
| Focal class | 21(24.7) | 4(16.7) | |
| Crescentic class | 21(24.7) | 6(25) | |
| Mixed class | 32(37.7) | 8(33.3) | |
| Sclerotic class | 11(12.9) | 6(25) | |
| Global glomerulosclerosis | 0.8 | ||
| Mild (0%–25%) | 52 (61.2) | 15 (62.5) | |
| Moderate (25%–50%) | 18 (21.2) | 4 (16.6) | |
| Severe (>50%) | 15 (17.6) | 5 (20.9) | |
| Fibrotic crescents/segmental sclerosis | 0.8 | ||
| None/mild (0%–25%) | 59 (70.2) | 19 (79.2) | |
| Moderate (25%–50%) | 14 (16.7) | 3 (12.5) | |
| Severe (>50%) | 12 (14.1) | 2 (8.3) | |
| Tubular atrophy | 0.08 | ||
| None/mild (0%–25%) | 42 (49.4) | 16 (66.7) | |
| Moderate (25%–50%) | 39 (45.9) | 6 (25) | |
| Severe (>50%) | 4 (4.7) | 2 (8.3) | |
| Interstitial fibrosis | 0.65 | ||
| None/mild (0%–25%) | 37 (43. 5) | 13 (54.2) | |
| Moderate (25%–50%) | 42 (49.4) | 10 (41.7) | |
| Severe (>50%) | 6 (7.1) | 1 (4.1) | |
| Chronicity (1–12) | 5.5 (2.4) | 5.2 (2.5) | 0.58 |
| Cellular crescents | 0.17 | ||
| Grade 1, 0%–25% | 42 (49.4) | 7 (29.2) | |
| Grade 2, 25%–50% | 21 (24.7) | 10 (41.6) | |
| Grade 3, >50% | 22 (25.9) | 7 (29.2) | |
| Glomerular necrosis | 0.21 | ||
| None/Mild (0%–25%) | 63 (74.1) | 15 (62.5) | |
| Moderate (25%–50%) | 17 (20) | 5 (20.8) | |
| Severe (>50%) | 5 (5.9) | 4 (16.7) | |
| Interstitial leucocyte infiltration | 0.005 | ||
| None/Mild (0%–25%) | 67 (78.8) | 14 (58.3) | 0.04 |
| Moderate (25%–50%) | 18 (21.2) | 7 (29.2) | 0.4 |
| Severe (>50%) | 0 | 3 (12.5) | 0.0007 |
| Circumferential crescents | 29(34.5) | 13(54.2) | 0.08 |
| Red blood cell casts | 26 (31) | 12(50) | 0.08 |
| Fibrinoid necrosis in the vessel wall | 5 (6) | 5(20.8) | 0.02 |
| Activity score (1–12) | 4.98 (1.9) | 6.33 (2.5) | <0.01 |
| Arteriosclerosis | 0.82 | ||
| None/mild | 32 (37.6) | 8 (33.3) | |
| Moderate | 37 (43.5) | 12 (50) | |
| Severe | 16 (18.9) | 4 (16.7) | |
| Immunofluorescence findings | n = 85 | = 24 | |
| C3 0 | 40 (44) | 11 (45.8) | |
| C3 any staining | 25 (27.4) | 3 (12.5) | |
| C3 1+ | 10 (11) | 5 (20.8) | |
| C3 2+ | 15 (17.6) | 5 (20.8) |
Data are n (%) or mean (SD).
EUVAS, European Vasculitis Society; GFR, glomerular filtration rate.