IgA Nephropathy in children and adults: comparison of histologic features and clinical outcomes

Background. While some studies have reported that IgA nephropathy has a relatively benign clinical course in children, others have shown that renal outcomes of paediatric patients with IgA nephropathy followed into adulthood are similar to those of patients diagnosed as adults. Some of this variability may be related to differences in histologic severity of cohorts of patients diagnosed as children versus adults. Methods. We retrospectively examined correlations between renal biopsy findings, clinical features at presentation and renal survival in 99 children and adolescents (≤17 years old) with IgA nephropathy and compared these findings to those of 125 adults with IgA nephropathy. Results. Compared with adults, paediatric patients were more likely to have minimal histologic lesions (24% versus 14%) and less likely to have advanced chronic lesions (3% versus 17%). Similar fractions of paediatric and adult patients showed focal and diffuse glomerulonephritis (GN), respectively. Among these latter two groups, renal survival was significantly better in patients diagnosed as children than as adults by univariate and multivariate analyses. By multivariate analysis, other significant, independent predictors of renal survival were estimated percent interstitial fibrosis and histologic grade (diffuse versus focal GN). Conclusions. In patients with proliferative IgA nephropathy, the clinical course is more likely to be benign when the disease is diagnosed in childhood versus adulthood. This difference can be accounted for only in part by more advanced disease at the time of biopsy in adults.