Renal outcome in IgA nephropathy according to Oxford classification and ultrastructural analysis in a Brazilian center .

AIMS: Correlate clinical and histologic features with renal outcome in patients with biopsy-proven IgA nephropathy (IgAN).

MATERIALS AND METHODS: Retrospective analysis of records and renal tissue of IgAN patients. Histology was revised according to MEST score of Oxford classification. Focal segmental glomerulosclerosis (FSGS) features were assessed by light microscopy. Electron microscopy review searched for podocyte effacement.

RESULTS: 67 patients were included, 56.7% men, mean age 34.5 ± 12.5 years, mean arterial pressure (MAP) 106 ± 18 mmHg, estimated glomerular filtration rate (eGFR) 63.32 ± 43.07 mL/min/1.73m² and proteinuria 3.1 ± 2.2 g/24 h. M1 was seen in 38 patients (56.7%), E1 in 12 (17.9%), S1 in 49 (73.1%), T1 in 18 (26.8%), and T2 in 17 (25.3%). Mean effacement index (EI) was 0.81 ± 0.18 and did not correlate with proteinuria. 27 patients (40.2%) had end-stage renal disease (ESRD) which correlated with MAP (p = 0.002), eGFR (p = 0.0003), T1 (p = 0.0008) and T2 (p = 0.0001), follow-up MAP (p = 0.02) and follow-up proteinuria (p = 0.01 for 1.0 - 4.0 g/24 h and p = 0.005 for ≥ 4.0 g/24 h). T score correlated with MAP and proteinuria at baseline (p = 0.0001 and 0.0097, respectively) and during follow-up (p = 0.0001 and < 0.0001, respectively). Podocyte hypertrophy correlated with MAP at baseline and during follow-up (p = 0.0046 and 0.0295, respectively). Tip lesion correlated with MAP at baseline (p = 0.0228). There was no correlation between FSGS features or EI with proteinuria or ESRD.

CONCLUSIONS: Our data corroborate eGFR, proteinuria, MAP and T score as risk factors for ESRD in IgAN. Most patients had diffuse podocyte effacement, probably secondary to factors unrelated to proteinuria.
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