IgA Nephropathy in Children: A Multicenter Study in Poland

Abstract

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 m (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.

IgA Nephropathies in Children: Epidemiological, Clinical, Histological and Evolutionary Profile: About 31 Cases

“…The annual incidence of IgA nephropathies in our series is evaluated at 3 cases per year. This number is identical to the result of the study carried out by Cambier (2017) [15], whereas the study carried out by MIZERSKA [16] displays 9cas per year. Global distribution disparities are explained by genetic influence [17], screening for microscopic hematuria and indications for kidney biopsy.…”

“…In our series, the mean age of our patients is 10 years in BM and 7.5 in RA, which is consistent with data in the literature. The male predominance has been observed in Berger's disease with a sex ratio of 9, the latter being between 1.5 and 3 in the pediatric literature [16,19,[22][23][24][25][26].…”

Pediatric IgA Nephropathy in Europe

“…The different criteria to perform renal biopsies in European children with oligo-symptomatic urinary abnormalities account for the variability in the reports on the clinical presentation at renal biopsy and the natural course of pediatric IgAN in Europe [1-3]. For this reason, to gain a general overview of this glomerular disease in children, a suitable observational approach is offered by the cohort gathered by the collaborative study to validate the Oxford Classification of IgAN, VALIGA [9].…”

“…Europe is the second continent with a frequency of this disease accounting for 20% of renal biopsies performed in pediatric age [1-3], while Asia has a 40% frequency [4, 5]. This different prevalence might be due to genetic or environmental factors, which play a greater role in Asia than in Europe, particularly favoring the early onset of IgAN [6].…”

“…However, most probably, the frequency increases where screening programs are active, like in Japan and Korea [5, 7]. In Europe, this policy has not been adopted, and IgAN is diagnosed in children undergoing renal biopsy because of persistent heavy isolated microscopic hematuria or hematuria associated with non-nephrotic proteinuria [1-3]. The prevalence of pediatric IgAN in Europe varies in different reports, due to the variable criteria for performing renal biopsy in young subjects shortly after the detection of urine anomalies or limiting renal biopsy to cases having developed proteinuria.…”