Definition of kidney outcome, of indications to second biopsy and of histological score
| Definition of kidney events | ||||
| KFI | Decrease in eGFR ≥30% confirmed by at least three determinations for at least 3 months | |||
| Proteinuric flare21 | Increase in proteinuria without modification of serum creatinine of at least 2 g/24 hours if the previous proteinuria was <3.5 g/24 hours or doubling if previous proteinuria was ≥3.5 g/24 hours | |||
| Nephritic flare21 | Increase in serum creatinine of at least 30% over the last value, associated with nephritic urinary sediment, with or without increased proteinuria | |||
| Arterial hypertension | Systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg in sitting position (mean of three consecutive measurements) | |||
| Complete kidney response | Proteinuria<0.5 g/24 hours, normal or near normal eGFR (within 10% of normal eGFR of previously abnormal) | |||
| No complete kidney response | All the other cases | |||
| Histological assessment | ||||
| Light microscopy | Specimen fixed in 5% formalin Stains used: H&E, periodic acid-Schiff, silver methenamine and Masson’s trichrome/AFOG | |||
| 0 | 1+ | 2+ | 3+ | |
| Neutrophil infiltration/karyorrhexis Endocapillary hypercellularity Hyaline deposits Cellular/fibrocellular crescents Fibrous crescents Fibrinoid necrosis Glomerular sclerosis | Absent | Mild (<25% of glomeruli) | Moderate (25%–50% of glomeruli) | Severe (>50% of glomeruli) |
| Interstitial inflammation Interstitial fibrosis Tubular atrophy | Absent | Mild (<25% of the cortex) | Moderate (25%–50% of the cortex) | Severe (>50% of the cortex) |
AFOG, Acid Fuchsin Orange G; eGFR, estimated glomerular filtration rate; KFI, kidney function impairment.