The demographic and clinical characteristics of children with IgAV or IgAVN.

Joint: 0 = no symptoms;1 = pain and/or slightly swelling; 2 = pain and/or moderately swelling; 3 = pain and/or severely swelling; GI: 0 = no symptom; 1 = slight pain and/or occult stool blood(OSB) (+); 2 = moderate pain and/or OSB(+2,+3); 3 = severe and/or maelena; Kidney: 0 = no proteinuria; 1 = proteinuria(+) and/or hematuria(+); 2 = proteinuria(2+,3+) and/or hematuria(2+,3+); 3 = proteinuria(>3+) and/or hematuria(>3+).The demographic and clinical characteristics of children with IgAV or IgAVN.