engleski

The paediatric vasculitis activity score (PVAS) and proteinuria in IgAV nephritis: is there an association with different histologic findings?

Introduction: IgA vasculitis (IgAV) is usually self-limiting with a favorable prognosis. However, the development of nephritis (IgAVN) can lead to chronic kidney disease and kidney biopsy has been a continued standard in determining the severity of IgAVN. The association between the disease activity, as well as laboratory parameters descibing kidney function, and different histologic classifications used for IgAVN are still left unclear. Objectives: To determine whether there is an association between histologic variables, measures of disease activity (PVAS) and markers of kidney function. Methods: Patients included were diagnosed with IgAV and IgAVN based on EULAR/PRINTO/PRES criteria in the period from 2003 to 2021. Their renal biopsy findings were examined using light microscopy, immunofluorescence, and electron microscopy analyses. Four classifications were used: ISKDC, Haas classification, Oxford classification, and SQC classification. PVAS was determined at the time of diagnosis. Results: The study included 67 patients, with the median (range) age of 10.8 (3.1-28.5) years at the diagnosis. Fifty-eight percent of patients were male, with a male to female ratio of 1.4:1. The median time from IgAV diagnosis to IgAV nephritis was 5 (0-270) days. The median time from the onset of nephritis to kidney biopsy was 30 (2-2555) days. Laboratory parameters were tested for association with all four classifications. Twenty- four hours protein excretion has shown statistically significant correlation with higher grade in Oxford classification (b= 0.58 ± 0.12, p <0.001), SQC classification (b= 0.44 ± 0.11, p <0.001), and ISKDC classification (b= 0.36 ± 0.11, p <0.001), but not with Haas classification. However, it was found that patients with hematuria had a higher grade in Haas classification, in comparison with patients without hematuria (b= 1.93 ± 0.49, p <0.001). The median (range) PVAS of our patients at diagnosis was 15 (2-30). We explored whether there is an association between the activity of the disease and histologic variables. Endocapillary proliferation and tubular atrophy from Oxford classification were found to associate with PVAS.Endocapillary proliferation showed a statistically significant positive correlation (b= 0.70 ± 0.25, p =0.008), while tubular atrophy was negatively associated (b= -1.39 ± 0.55, p =0.015). Conclusion: Our findings suggest that a higher 24h urine protein excretion could be a possible indicator of higher grades in ISKDC, Oxford and SQC classifications. Furthermore, we have found that when the activity index is high, we could expect acute histologic changes such as endocapillary proliferation, while chronic changes, such as tubular atrophy, could occur after the PVAS score decreases. Support: Research is supported by Croatian Science Foundation project IP-2019-04-8822

IgA vasculitis ; IgA vasculitis nephritis ; PVAS

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