[Clinical features of IgA vasculitis with positive antineutrophil cytoplasmic antibody in children].

To analyze the clinical features and risk factors for renal injury in children with antineutrophil cytoplasmic antibody (ANCA)-positive IgA vasculitis (IgAV). A case-control study was conducted. Seventy-two ANCA-positive IgAV children hospitalized at the Children's Hospital of Chongqing Medical University from January 2017 to October 2022 were enrolled as the ANCA-positive group. Propensity score matching (1∶4) using the nearest neighbor was performed with age and gender as covariate, and 288 cases ANCA-negative IgAV children were included as the ANCA-negative group. Patients with renal injury were named ANCA-positive IgAV nephritis (IgAVN) group and ANCA-negative IgAVN group, respectively. The ANCA-positive IgAVN group was further divided into myeloperoxidase (MPO) group and proteinase 3 (PR3) group based on the type of ANCA. Clinical data including manifestations, laboratory tests, renal injury, and prognosis were collected. Comparisons between groups were performed using independent sample -tests, Mann-Whitney tests, tests, or Fisher's exact tests. Kaplan-Meier curves were used to assess differences in the time to renal injury onset, and multivariate logistic regression was performed to identify independent risk factors for renal injury. Among the 72 ANCA-positive IgAV children (41 males, 31 females, age of 7.7 (5.3, 11.2) years), no significant difference in age or gender was observed compared to the ANCA-negative group (both >0.05). The ANCA-positive group had higher IgM levels, a higher incidence of recurrent rash, and shorter thrombin time (all <0.05). Among children with renal injury, the ANCA-positive group showed significant differences in the incidence of hematuria, clinical classification, and grade A prognosis compared to the ANCA-negative group (all 0.05), but no difference was found in the time to renal involvement onest or renal pathology (all 0.05). The MPO group had higher rates of microscopic hematuria, gross hematuria, acute renal insufficiency, glomerular sclerosis, and grade B prognosis compared to the ANCA-negative IgAVN group (all 0.05), with a later onset of renal involvement (0.05). Elevated serum creatinine (=1.08, 95% 1.03-1.14) and shortened thrombin time (=0.71, 95% 0.55-0.92) were independent risk factors for renal injury in ANCA-positive IgAV children (all <0.05). Children with ANCA-positive IgAV are more likely to experience recurrent rash. MPO-ANCA-positive IgAVN children have higher risks of hematuria, acute kidney injury and glomerular sclerosis, with later-onset but poorer renal prognosis compared to ANCA-negative IgAVN children. Higher serum creatinine levels and shorter thrombin time may be associated with renal injury in children with ANCA-positive IgAV.