Analysis of children with Henoch-Schonlein purpura secondary to infection

Objectives Henoch-Schonlein purpura (HSP) is the most common childhood vasculitis, infection is the most essential inducement. We hypothesized that infection could impact the blood routine characteristics and/or outcome of vasculitis. Thus, we aim to find the most common infectious agent in HSP patients and identify convenient indicators to predict renal involvement in HSP patients with infection. Method We conducted a retrospective study of 208 HSP children and 98 healthy children. Clinical parameters were compared in those cases. Results A total of 68.75% of patients were infected with various pathogens. The mean platelet volume (MPV) (P < 0.02) was lower in HSP patients with infection than patients without infection. Mycoplasma pneumoniae (MP) infection accounted for the largest proportion (45.77%). MPV in HSP nephritis (HSPN) group was lower than in HSP patients (excluded renal involvement) in patients with MP infection. Logistic regression analysis found that age and MPV were risk factors for the occurrence of MP-infected HSPN. The receiver operating characteristic curve (ROC) analysis showed that the combination of MPV with the onset age at the optimal cut-off point had 81% sensitivity in predicting whether HSP patients with MP infection would develop into HSPN. Conclusions Our research revealed that MP was the most commonly infected pathogen of children's HSP. MPV was an essential predictor of nephritis in HSP patients with MP infection. This discovery can prompt clinical treatments as well as reduce costs.