Clinicopathologic Study on Prognostic Markers in IgA Nephropathy

Abstract

Background/Aim: Few prognostic markers have found general acceptance in IgA nephropathy (IgAN). The aim of the present study was to search for significant predictor(s) at the time of biopsy. Methods: Fifty-five patients with IgAN undergoing evaluation and treatment at our institution were examined regarding clinicopathologic features at the time of renal biopsy and, if possible, at follow-up. Factors predictive of outcome were evaluated. Renal histopathology was quantified using a glomerulosclerosis index (GSI), a tubulointerstitial index (TII), and a crescent index (CI). Results: The serum creatinine concentration (S-Cr) showed positive correlations with proteinuria and serum total cholesterol concentration, as well as with histopathologic findings. Heavy proteinuria (≧3.0 g/24 h) was associated with higher S-Cr and greater severity of pathologic abnormalities than with milder proteinuria. At follow-up, 6 patients progressed to chronic renal insufficiency, in whom the S-Cr increased by at least 50% to reach or exceed 1.5 mg/dl (132.6 µmol/l). By univariate analysis, elevated GSI, TII, and S-Cr, presence of nephrotic syndrome, elevated CI, and elevated total cholesterol were found to be negative predictors, in descending order of odds ratio. In multivariate analysis, however, only TII independently predicted unfavorable outcome. Conclusion: Renal biopsy in IgAN may be the most powerful predictor for renal outcome; an advanced tubulointerstitial lesion is unfavorable.