[Severity of glomerular damage with IgA nephropathy and renal prognosis: a comparison between pattern classification...

In our laboratory, a semi-quantitative pattern classification (PC) for the distribution pattern of glomerular sclerotic lesions in biopsied renal specimens with IgA nephropathy has been utilized, and found to be quite beneficial for predicting the patient's prognosis. In the present study conducted to re-evaluate this classification, 503 patients with IgA nephropathy (male/female, 256/247; mean age: 32.1 +/- 13.5 yrs; follow-up: 9.3 +/- 4.5 yrs) were used. The patients had been divided originally into 5 groups based on a previous PC: minimal, mild, moderate, severe and advanced groups. Their glomerular lesions were classified as mild, moderate, severe and global sclerosis, and were given scores of 1-4 points. The mean glomerular score was then calculated for each patient, as a value of the calculated classification (CC), and all patients were then re-divided into 5 groups based on their scores. The renal survival curves in the CC were similar to those in PC, and no significant differences in the renal survival rates were found between the classifications in each group, thus suggesting that the CC has a similar predictive power for renal survival. Although 7 of 39 cases (18%) with global sclerosis in PC groups 4 and 5 shifted down to CC group 3, of 61 patients with global sclerosis in PC group 1 who had a good prognosis, 26 cases (43%) shifted up to the CC group 2 and 6 cases (8%) changed to the CC group 3. As a result, the predictive power in patients in the lower CC groups was lost for the renal survival rate. In conclusion, statistical comparison between the PC and CC groups revealed that global sclerosis presents in non/minimally affected glomeruli as a nonspecific alteration. Severely advanced cases also possess a high incidence of globally sclerotic glomeruli (87%), and therefore the occurrence of global sclerosis may involve two different pathogenic mechanisms.