Risk factors of renal involvement in children with primary Henoch-Schönlein purpura in the early stage

Objective To explore the risk factors of renal involvement in children with primary Henoch-Schonlein purpura (HSP) in the early stage, and provide clinical references for early intervention of HSP these children with risk factors of renal involvement. Methods A total of 1 402 children with primary HSP who hospitalized in Department of Pediatrics, West China Second University Hospital, Sichuan University from January 2011 to December 2015 were included in this study. According to whether combined with renal involvement or not in the early stage of HSP, these children were divided into the renal involvement group (n=423) and control group (n=979, without renal involvement). Their demographic data and clinical manifestation were collected by retrospective method. Constituent ratios of gender, age of onset, residential area, season of onset and duration from symptoms onset to diagnosis, and incidences of skin rash, gastrointestinal symptoms, joint swelling and pain, renal involvement, angioneurotic edema, and nervous system involvement in the early stage were compared between two groups by chi-square test. Multivariate unconditional logistic regression analysis was used to assess the risk factors of renal involvement in children with HSP in the early stage. This study was in line with the World Medical Association Declaration of Helsinki revised in 2013. The guardians of all children signed the clinical research informed consents. Results ①Among the 1 402 children with HSP, 423 cases (30.17%) occurred renal involvement in the early stage of onset, 937 cases (66.84%) with gastrointestinal symptoms, 609 cases (43.33%) with joint swelling and pain, 352 cases (25.11%) with angioneurotic edema, 31 cases (2.21%) with nervous system involvement, and all cases (100%) with skin rash. ②Univariate analysis of the influencing factors of renal involvement in the early stage of HSP showed that there were statistically significant differences between two groups in constituent ratios of age of onset, season of onset, and duration from symptoms onset to diagnosis (χ2=53.682, P<0.001; χ2=11.990, P=0.007; χ2=14.635, P<0.001). And the proportions of children lived in rural areas, without joint swelling or pain and with angioneurotic edema in renal involvement group all were statistically higher than those in control group, and all the differences were statistically significant (χ2=10.032, P=0.002; χ2=6.514, P=0.011; χ2=6.362, P=0.012). ③Multivariate unconditional logistic regression analysis results showed that the onset age of HSP≥5 years old (≥5-7 years old, OR=2.23, 95%CI: 1.42-3.51, P<0.001; ≥7-9 years old, OR=2.38, 95%CI: 1.51-3.76, P<0.001; ≥9 years old, OR=4.11, 95%CI: 2.65-6.36, P<0.001), onset in the autumn (OR=1.61, 95%CI: 1.09-2.37, P=0.014) and winter (OR=1.79, 95%CI: 1.09-2.37, P=0.001), the duration from symptoms onset to diagnosis ≥8 d (OR=1.59, 95%CI: 1.17-2.17, P=0.004), living in rural areas (OR=1.37, 95%CI: 1.07-1.76, P=0.012) and combined with angioneurotic edema (OR=1.74, 95%CI: 1.32-2.31, P<0.001) were independent risk factors for renal involvement in children with HSP in the early stage. While combined with joint swelling and pain (OR=0.77, 95%CI: 0.60-0.99, P=0.038) was independent protective factors for renal involvement in children with HSP in the early stage. Conclusions Results in this study first show that HSP children combined with angioneurotic edema have high risk of renal involvement in the early stage of HSP and reconfirm that onset age of HSP ≥5 years old, onset in autumn or winter, duration from symptoms onset to diagnosis ≥8 d, and residence in rural areas all are the independent risk factors for renal involvements in children with primary HSP in the early stage. Key words: Purpura, Schoenlein-Henoch; Risk factors; Angioedema; Renal involvement; Early stage of onset; Age of onset; Complications; Child