Comparative study on clinicopathological features and prognosis of IgA vasculitis nephritis and IgA nephropathy in children

Abstract

Background Although IgA vasculitis nephritis (IgAVN) and IgA nephropathy (IgAN) have many clinical and pathological parallels, they also have some differences, and their relationship has not yet been determined. This paper examines the differences in clinicopathology and prognosis between kids with IgAVN and IgAN. Methods We retrospectively analyzed the data of 809 children with IgAVN and 236 children with IgAN between January 2006 and December 2021 to compare the similarities and differences between IgAVN and IgAN in clinicopathology and prognosis. Results IgAN was more prevalent in the summer, whereas IgAVN was more common in the fall (P < 0.0001). IgAN tubular interstitial injury is more severe, chronicity index and total biopsy score were higher than IgAVN (P < 0.0001). The deposition intensity of C3, and the deposition rate of IgA pure in the mesangium, were higher in IgAVN than in IgAN (P < 0.0001), and the intensity of IgA deposition was also higher in IgAVN (P = 0.003). IgAVN had a better prognosis and a higher kidney remission rate (P < 0.0001). Cox regression revealed interstitial fibrosis as an independent risk factor for poor prognosis of IgAVN (HR = 1.449, 95%CI:1.011–2.076, P = 0.043) and IgAN (HR = 2.384, 95%CI:1.313–5.024, P = 0.022). Furthermore, IgA++ (HR = 2.25, 95%CI:1.212–4.175, P = 0.01) and IgA+++ (HR = 12.043, 95%CI:1.498–96.854, P = 0.019) could be risk factors for bad prognosis of IgAVN. Conclusions IgAN was more severe than IgAVN regarding kidney impairment, interstitial damage, and prognosis. There were different levels and locations of immune complex deposition in the kidneys, supporting the notion that they are two distinct diseases. The intensity of IgA deposition may be a risk factor for poor IgAVN prognosis.