Sobrevida renal em crianças e adolescentes com nefropatia por imunodepósitos de IgA

Abstract

Introduction IgA Nephropathy was considered a benign disease as well as a kidney disorder with good prognosis in the past. However, prospective studies with long-term follow-up showed progression to chronic kidney disease in adults as well as in children. Objectives The objectives of this study were to evaluate the evolution of renal function in children and adolescents with IgAN, followed at the Unit of Pediatric Nephrology at the Hospital de Clínicas da Faculdade de Medicina da Universidade Federal de Minas Gerais (UNPHC - FM - UFMG) between 1987 and 2007, and to identify unusual risk factors for progressive loss of renal function within this population. Methods It was a retrospective cohort, observational, from demographic data, clinical and analysis of renal function survival in this population. Univariate analysis was conducted using Kaplan-Meyer survival curve and multivariate using Cox-regression model. Results The study evaluated 61 children, gender equally distributed (male 51%), 62% were considered white, mean age was 8.3 ± 4.0 years (median 8.0 yr) and median time of follow-up of 12 years (range 48 to 241 months).At the time of last evaluation, 4 (7%) of 61 original patients had end stage renal disease (ESRD), 10 (16%) had evidences of progressive chronic kidney disease (CKD), 25 (41%) had proteinuria (defined as protein/creatinine ratio > 0.50 (Proteinuria 1), 23 (38%) had protein/creatinine ratio > 2.0 (Proteinuria 2), and 13 (21%) had systemic arterial hypertention (SAH). Data analysis using the Cox regression model identified the age of onset of clinical symptoms as predictive of ESRD (RR 1.6; CI 95% 1.1-2.4; p=0.016). Each year in the age of clinical onset of the disease was correlated to a 60% increase in the risk of developing ESRD. The risk of Proteinuria (1) in children aged 8 years or older at onset of clinical manifestation of the disease is approximately 2.4 times higher than those younger than 8 (RR 2.4; CI 95% 1.0-5.8; p=0.05). For those with gross hematuria as initial clinical presentation, the risk of developing Proteinuria 1 is approximately 5-fold higher than those with microhematuria (RR 2.4; CI 95% 1.5-17.5; p=0.009). Family history of dialytic treatment increased the risk of proteinuria in nephrotic range by 3.4 times (RR 3.4; 95% CI 1.4-8.3; p=0.006). Conclusion An expressive part of this population developed unfavourable outcomes, which in turn, demands a rigorous follow-up of children and adolescents with IgA nephropathy. Age of clinical onset of the disease, gross hematuria, family history of dialytic treatment and hepatosplenomegaly were significantly associated with renal risk. Keywords: IgA nephropathy, hematuria, arterial hypertension, proteinuria, chronic renal disease, prognostic factors.