RESUMO
Introduction: IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. Decreased glomerular filtration rate is a known risk factor for disease progression. Aim: We aimed to examine factors that may contribute to disease progression in children that present with impaired eGFR at the onset of IgAN. Materials and methods: Of the 175 patients with IgAN from the Polish Registry of Children with IgAN and IgAVN, 54 (31%) patients with IgAN who had an onset of renal function impairment (GFR < 90 mL/min) were eligible for the study. All of them were analyzed for initial symptoms (GFR according to Schwartz formula, creatinine, proteinuria, IgA, C3), renal biopsy result with assessment by Oxford classification, treatment used (R-renoprotection, P-prednisone+R, Aza-azathioprine+P+R, Cyc-cyclophosphamide+P+R, CsA-cyclosporine+P+R, MMF-mycophenolate mofetil+P+R), and distant follow-up. Based on the GFR score obtained at the end, patients were divided into two groups: A-GFR > 90 mL/min and B-GFR < 90 mL/min. Results: In the study group, the mean age of onset was 12.87 ± 3.57 years, GFR was 66.1 ± 17.3 mL/min, and proteinuria was 18.1 (0-967) mg/kg/d. Renal biopsy was performed 0.2 (0-7) years after the onset of the disease, and MESTC score averaged 2.57 ± 1.6. Treatment was R only in 39% of children, P+R in 20%, Aza+P+R in 28%, Cyc+P+R in 9%, CsA+P+R in 7%, and MMF+P+R in 3%. The length of the observation period was 2.16 (0.05-11) years. At the follow-up, Group A had 30 patients (56%) and Group B had 24 patients (44%). There were no significant differences in any of the other biochemical parameters (except creatinine) or proteinuria values between the groups and the frequency of the MESTC score ≥ 2 and <2 was not significantly different between Groups A and B. Patients with normal GFR at the follow-up (Group A) were significantly more likely to have received prednisone and/or immunosuppressive treatment than those in Group B (p < 0.05) Conclusions: In a population of Polish children with IgAN and decreased renal function at the onset of the disease, 56% had normal GFR in remote observation. The use of immunosuppressive/corticosteroids treatment in children with IgAN and impaired glomerular filtration rate at the beginning of the disease may contribute to the normalization of GFR in the outcome, although this requires confirmation in a larger group of pediatric patients.
RESUMO
IgA nephropathy (IgAN) is the most common form of glomerulonephritis in pediatric population. The clinical presentation of the disease in children ranges from microscopic hematuria to end-stage kidney disease. The aim of the study was to retrospectively assess clinical and kidney biopsy features in children with IgAN. We assessed a cohort of 140 children, 88 boys, 52 girls with the diagnosis of IgAN in the period of 2000-2015, entered into the national Polish pediatric IgAN registry. The assessment included the following: proteinuria, hematuria, glomerular filtration rate (GFR), arterial blood pressure, and the renal pathological changes according to the Oxford classification and crescents formation, as modifiable and unmodifiable risk factors. The incidence of IgAN in Poland was set at 9.3 new cases per year. The mean age at onset of IgAN was 11.9 ± 4.3 years, and the most common presentation of the disease was the nephritic syndrome, recognized in 52 % of patients. Kidney biopsy was performed, on average, 1.3 ± 2.0 years after onset of disease. Based on the ROC analysis, a cut-off age at onset of disease for GFR <90 mL/min/1.73 m2 (risk factor of progression) was calculated as 13.9 years. Unmodifiable lesions: segmental sclerosis, tubular atrophy/interstitial fibrosis (S1, T1-2) in the Oxford classification and crescents in kidney biopsy were significantly more common in Gr 1 (>13.9 years) compared with Gr 2 (<13.9 years), despite a significantly shorter time to kidney biopsy in the former. We conclude that IgAN in children may be an insidious disease. A regular urine analysis, especially after respiratory tract infections, seems the best way for an early detection of the disease.
