IgA vasculitis (Henoch – Schönlein Purpura) as the first manifestation of juvenile Systemic Lupus Erythematosus: Case-control study and systematic review

BACKGROUND: We have recognized 15 children with jSLE and the antecedent of IgA vasculitis (HSP). This association is not broadly present in the literature. AIM: To know the age and gender distribution of children with IgA vasculitis (HSP), compare it to our IgA vasculitis (HSP) + jSLE cases, and identify prognostic factors to develop jSLE within our case series, IgA vasculitis (HSP) vs. IgA vasculitis (HSP) + jSLE. METHODS: A systematic review was carried out to know the age and gender distribution of children with IgA vasculitis (HSP). The information obtained plus data from 110 children with IgA vasculitis (HSP) from the Instituto Nacional de Pediatría were used to compare groups and identify prognostic factors. We performed a case-control study in patients < 18 years, consisting of 15 cases retrospectively identified with IgA vasculitis (HSP) + jSLE, and 110 IgA vasculitis (HSP) control subjects. RESULTS: The information of 12,819 IgA vasculitis (HSP) subjects from the systematic review and 110 IgA vasculitis (HSP) controls was obtained and compared to our 15 IgA vasculitis (HSP) + jSLE cases. The mean age of IgA vasculitis (HSP) was 7.1-years vs. 10.4-years of IgA vasculitis (HSP) + jSLE at the HSP diagnosis. Female to male ratio of IgA vasculitis (HSP) was 1:1.33 vs. 1:0.25 of IgA vasculitis (HSP) + jSLE. Patients with IgA vasculitis (HSP) + jSLE had lower levels of Hemoglobin (Hb) compared to patients with IgA vasculitis (HSP) 109 g/L vs. 141 g/L. For the development of jSLE, we found older age and lower levels of Hb as prognostic factors with OR [95% CI]: 1.37 [1.06, 1.89] and 5.39 [2.69, 15.25], respectively. CONCLUSION: IgA vasculitis (HSP) + jSLE patients are older and have lower levels of Hb than patients with IgA vasculitis (HSP). It is necessary to confirm these findings through a prospective study.