Prolonged skin involvement distinguishes adolescent from childhood-onset IgA vasculitis: a large multicenter study with 687 patients

Immunoglobulin A vasculitis (IgAV), also known as Henoch- Schönlein purpura (HSP), is the most common systemic vasculitis in childhood. Potential differences in demographic characteristics, clinical presentation, laboratory findings, and treatments approaches across age groups, remain poorly explored. To the best of our knowledge, no multicenter study in Latin America has systematically addressed these features. We aimed to assess demographic, clinical and laboratory features, and treatments in children versus adolescents with (IgAV)/ (HSP) in a large multicenter study. A multicenter study involving four tertiary centers evaluated 687 children and adolescents (≤ 18 years-old) with IgAV/HSP (EULAR/PRINTO/PRES classification criteria) at first 3 months after diagnosis. The charts were retrospectively assessed for demographic data, initial clinical manifestations, laboratory tests and treatments. Data were compared between children (< 10 years-old) and adolescents (≥ 10 years-old), according to WHO definition. IgAV/HSP was diagnosed in 599/687(87%) children [5.33(0.88–9.91) years-old] and 88/687(13%) adolescents [11.33(10-17.5) years-old]. The median duration of purpura/petechiae was significantly lower in children compared to adolescents [14(1-120) vs. 15(2–90) days, p = 0.04]. The frequency of persistent purpura/petechiae (≥ 6 weeks of duration) was significantly reduced in the former group (7.2% vs. 19.5%, p = 0.002), likewise the frequency of gastrointestinal bleeding (17% vs. 34.1%, p = 0.01) and proteinuria (49.7% vs. 84%, p = 0.002). In contrast, the frequencies of arthritis/arthralgia (82.7% vs. 73%, p = 0.03) and orchitis(16.6% vs. 4.8%, p = 0.04) were significantly higher in children. Further analysis of laboratory tests showed that the median value of serum IgA was significantly lower in children than in adolescents [179.1(40-1002.0) vs. 279.0(104.0-488.0) mg/dL, p = 0.01], whereas thrombocytosis was higher (40.1% vs. 23%, p = 0.007). Logistic regression demonstrated that persistent purpura/petechiae after IgAV/HSP diagnosis (OR = 18.337; 95%CI 1.245-270.137; p = 0.034) was the only independently associated variable with dependent variable (adolescent). In this large multicenter cohort, IgAV/HSP onset occurred rarely at adolescence, with a more prominent cutaneous involvement. Prolonged purpura/petechiae after IgAV/HSP diagnosis was associated with adolescent-onset IgAV/HSP, reinforcing the need for vigilant monitoring in this subgroup.