Outcome of IgA nephropathy in adults graded by chronic histological lesions

This prognostic study of primary immunoglobulin A (IgA) nephropathy focused on chronic irreversible glomerular sclerosis and interstitial fibrosis, ba sed on the premise that this disease is characterized by a protracted and, for many, progressive course. We used a chronicity-based histological gradi ng system to assess the biopsy specimens of 126 adults with IgA nephropathy over a median follow-up of 10 years. Our grading system included a glomeru lar grading (GG) of 1 to 3 based on the extent of glomerular sclerosis, a t ubulointerstitial grading (TIG) of 1 to 3 based on the degree of tubular lo ss or interstitial fibrosis, and the evaluation of hyaline arterioloscleros is (HA). These three histological parameters were correlated with each othe r and with serum creatinine level, degree of proteinuria, and blood pressur e at the time of renal biopsy. Univariate analysis showed that these three histological and three clinical parameters were significantly correlated wi th renal survival. By multivariate analysis using the Cox regression model, GG, serum creatinine level, and degree of proteinuria represented independ ent prognostic factors of renal survival. For a subset of patients at a rel atively early stage of disease with a serum creatinine level less than 130 mu mol/L at the time of biopsy, all three histological features and degree of proteinuria were significantly correlated with renal survival, and GG wa s the only independent prognostic factor for renal outcome. This study show s that glomerular sclerosis represents the most important prognostic factor in adult patients with primary IgA nephropathy and has a strong predictive value, Our chronicity-based histological grading system not only correlate s well with the natural history of IgA nephropathy but is also reproducible and relatively simple to apply. (C) 2000 by the National Kidney Foundation , Inc.