Persistence and Severity of Cutaneous Manifestations in IgA Vasculitis Is Associated with Development of IgA Vasculitis Nephritis in Children

<b><i>Background/Objective:</i></b> The purpose of this study was to evaluate the prevalence and severity of skin involvement in children with IgA vasculitis (IgAV) and its relationship with clinical and biochemical parameters and the risk of developing IgA vasculitis nephritis (IgAVN), the only cause of long-term morbidity and the main prognostic factor in IgAV patients. <b><i>Methods:</i></b> This national multicenter retrospective study included 611 patients under the age of 18 years with IgAV referred to five Croatian tertiary hospitals between 2009 and 2019. Patient data were collected from a database with systematic analysis of IgAV patients in the Croatian population. <b><i>Results:</i></b> Among the 611 children, 205 (33.55%) had purpura on the lower extremities, in 207 (33.88%) the rash extended on the trunk, in 149 (24.39%) it extended to the upper extremities, in 32 (5.24%) the rash was generalized, while 15 (2.47%) had the most severe skin symptoms: bullae, ulcerations, and necroses. IgAVN developed in 130 (21.28%) and persistent IgAVN (present for &#x3e;3 months) in 48 (7.86%) children. Multivariate logistic regression found that presence of ulcerations and necroses (OR 3.20 [95% CI 1.03–9.91]), persistent purpura (OR 2.89 [95% CI 1.71–4.88]), and higher age (OR 1.16 [95% CI 1.09–1.23]) were significant predictors of IgAVN, whereas persistent purpura (OR 20.11 [95% CI 1.09–372.52]), male sex (OR 3.32 [95% CI 1.13–9.80]), and higher age (OR 1.15 [95% CI 1.00–1.30]) were predictors of persistent IgAVN. Among the laboratory parameters, higher serum urea (OR 1.43 [95% CI 1.03–2.00]) and reduction in activated partial thromboplastin time (OR 0.83 [95% CI 0.74–0.93]) were shown to have a significant impact on increasing the risk of persistent IgAVN. <b><i>Conclusion:</i></b> With increasing severity and duration of cutaneous manifestations in IgAV, the risk of developing IgAVN increases, making the prognosis worse, with a greater likelihood to need more aggressive treatment.