Tubular lesions determine prognosis of IgA nephropathy.

To assess the prognostic value of histological classification for renal outcome, we did a multivariate analysis of 194 patients with immunoglobulin A (IgA) nephropathy between 1985 and 1995. We also evaluated semiquantitative scales of tubular lesions and vessel lesions. At the time of the biopsy, 65 patients (33.5%) had chronic renal failure. At the end of the follow-up, 33 patients (17%) required hemodialysis. The mean age of the patients was 37.8 +/-18.9 years with predominance of men (sex-ratio: 3.12). Patients were followed-up for a mean of 43.2 +/- 37.2 months. Univariate analysis showed that hypertension (P < 10(-4)), nephrotic syndrome (P = 0.01), and crescents (P = 0.02) were significant in predicting renal failure, unlike subendothelial topography of IgA deposits (P = 0.05) and proteinuria (P = 0.05). Hematuria was a protective factor (P = 0.03). Multivariate analysis showed that tubular grade 2 (relative risk [RR], 5.5) and tubular grade 3 (RR = 28.8) were the best factors to predict chronic renal failure. The histological classification of Haas was significant in the univariate analysis, but not in the multivariate analysis. Tubular grading predicted renal outcome better than did the other histological parameters.