[Prognosis and risk factors of IgA vasculitis nephritis in children].

<b>Objective:</b> To investigate the prognosis and risk factors of IgA vasculitis nephritis (IgAVN) in children. <b>Methods:</b> A retrospective cohort study was conducted. Clinical data were collected from 264 children who were pathologically diagnosed with IgAVN at Department of Pediatric Nephrology, Tongji Hospital, affiliated with Tongji Medical College, Huazhong University of Science and Technology, between January 2011 and December 2017. All patients had a follow-up period of more than 3 years. Clinical characteristics, renal pathology, 3-year and 5-year prognosis were analyzed. The patients were grouped based on gender, age of onset (≤6 years, >6-9 years, and >9 years), pathological classification (≤Ⅲ and>Ⅲ),whether the prognosis was complete remission at 3 and 5 years. Independent sample <i>t</i>-tests, ANOVA or chi-squared test were used for intergroup comparisons. Spearman correlation analysis was applied for ordinal data, and multivariate Logistic regression was used to analyze factors affecting the prognosis. Receiver operating characteristic (ROC) curve was utilized to evaluate the predictive value of these factors. <b>Results:</b> Of the 264 children with IgAVN, 153 were male and 111 were female, the age of onset was 8.3 (6.7, 10.3) years, 118 patients (45%) with onset age >6-9 years accounted for the highest proportion. All patients presented with skin purpura and renal involvement, primarily manifesting as hematuria and/or proteinuria. Microscopic hematuria was observed in 253 patients (95.8%), while 246 patients (93.2%) showed proteinuria. In 256 patients (97.0%), hematuria or proteinuria urinalysis was detected within 6 months of skin purpura onset, and 243 patients (92.0%) underwent renal biopsy within 6 months of renal involvement. The most common clinical subtype in 264 IgAVN children was hematuria and proteinuria (204 cases, 77.3%), with grade Ⅲ being the predominant pathological classification (181 cases, 68.6%). Among children ≤6 years old, the 3-year complete remission rate was higher in males than in females (83.9% (26/31) <i>vs.</i> 7/16, <i>χ</i>²=8.12, <i>P</i>=0.012). Factors independently associated with poor 5-year prognosis included time from hematuria or proteinuria urinalysis to renal biopsy >6 months, elevated serum cholesterol levels, and incomplete remission 3 years post-biopsy (<i>OR</i>=5.41, 1.39, 6.02, 95%<i>CI</i> 1.40-20.86, 1.04-1.84, 2.61-13.88, all <i>P</i><0.05). The serum cholesterol has a predictive value for 5-year prognosis (<i>P</i>=0.020, AUC=0.62, 95%<i>CI</i> 0.52-0.71, Youden index=0.27, cutoff=4.37). <b>Conclusions:</b> For children with IgAVN aged≤6 years, the 3-year prognosis is better in males than in females. Time from hematuria or proteinuria urinalysis to renal biopsy >6 months, elevated serum cholesterol levels, and incomplete remission at 3 years post-biopsy may be independent risk factors for poor 5-year prognosis in children with IgAVN.