Henoch-Sch？nlein purpura nephritis in children: experience of the two tertiary care centers for pediatric and adolescent rheumatology of the Republic of Croatia from 2006 to 2017

Sa？etak Aim: To determine types of renal complications, indications for biopsy, treatment methods and possible outcomes in patients with Henoch-Sch？nlein purpura nephritis. Patients and methods: Retrospective analysis of medical data of HSP patients treated at the Department of Paediatrics, University Hospital Centre Zagreb, and the Department of Paediatrics, University Hospital Centre Split, during the period from 2006 to 2017, who developed kidney disease according to EULAR/PRINTO/PRES criteria. Results: Out of 378 patients diagnosed with HSP, 81 (21.4%) developed kidney disease, out of whom 43 boys (53.1%) and 38 girls (46.9%), with the median age 8.4 years (2.5 16.8).. A statistically significant increase of patients with HSP was during autumn and winter. There is a greater chance of nephritis with the increase of patients age at diagnosis. For every year (from 1 to 17 years) the chances increase by around 2.25%. Equal number of patients, 44.45%, had both hematuria and proteinuria or isolated hematuria, and only 11.1% isolated proteinuria. Renal biopsy was performed in 37 patients (45.7%), and most biopted patients were from concurrent hematuria and proteinuria group (70.3%). Children with isolated hematuria or with isolated proteinuria were most often treated with corticosteroids while children with hematuria and proteinuria were most often treated with corticosteroids and angiotensin- -converting enzyme inhibitors. Immunosuppressives were used in 16% of the patients, including most of those in the group with concurrent hematuria and proteinuria (69.2%). Only one patient (1.2%) developed renal insufficiency with the need for dialysis, while the outcome of the others was evaluated as good. Conclusion: Renal complications are the most important factor in the outcome of patients with HSP. For the optimal treatment of these patients it is necessary to bring consensus about the indications for kidney biopsy in HSP, and also to validate the existing pathohistological classification to affirm which one best correlates with the adverse outcome of the disease