Predisposing factors of childhood Henoch-Sch ö nlein purpura in Anhui province, China.

Henoch-Schönlein purpura (HSP) is a common autoimmune vasculitis in childhood. The detailed pathogenesis of HSP is still unclear, whereas several types of predisposing factors have been proved to be the initial step. The objectives of present study were to analyze the distribution of predisposing factors, association of the predisposing factors with clinical manifestations and HSP relapse/recurrence. 1200 children with HSP were recruited between January 2015 and December 2017. We reviewed their laboratory tests and medical histories associated with HSP onset. The annual incidence of HSP was 8.13-9.17 per 100 000 in Anhui province. HSP occurred more commonly in spring and winter than in summer with an obvious west-to-east gradient. Cutaneous purpura was the most prevalent manifestation (100%), followed by arthritis/arthralgias (43.67%), abdominal pain (40.17%) and renal involvement (18.17%). On admission, series of potential infections were identified in 611 patients (50.92%). The histories of allergy, injury, surgery, vaccination and tick bite were declared by 231 patients (19.25%), 15 patients (1.25%), 12 patients (1.00%), 4 patients (0.33%) and 3 patients (0.25%), respectively. However, predisposing factors could not be identified in 521 children with HSP (43.42%) yet. 123 cases (10.25%) relapsed or recurred more than one time; the mean number was 2.92, and the mean interval was 11.4 weeks. The infection is the most frequent predisposing factor regardless of clinical phenotypes and relapse/recurrence, whereas the clinical manifestations exhibit an obvious heterogenicity according to different predisposing factors.