Background: The purpose of this study was to propose clinical and pathologic criteria for the indication for steroid therapy (ST) in adult IgA nephropathy (IgAN).
Methods: We analyzed 275 adult IgAN patients retrospectively, using a histological scoring system. The histological score was expressed by evaluating, semiquantitatively, the extent of glomerular and tubulointerstitial lesions in terms of the activity index (AI) and chronicity index (CI). To determine the applicability of ST, three groups were categorized by evaluating the statistical significance of the correlation between the AI and CI, together with the daily amount of urinary protein (UP) and the outcome.
Results: In group A, which had a CI > or = 5 alone, 33 out of 43 patients showed a decline in renal function. There was no statistically significant difference between the subgroup with ST and that without ST. In group B, which had CI < 5, AI < 5, and UP < 1.0 g/day, 169 out of 174 patients had normal renal function irrespective of whether or not they received ST. Thus, ST had no beneficial effects in group A and B patients. In group C, which had CI < 5 and AI > or = 5 or UP > or = 1.0 g/day, patients with ST had a significantly higher incidence of an outcome with normal renal function (22 out of 24 patients) than that in patients without ST (19 out of 34 patients) (P < 0.01). Thus, ST had beneficial effects in group C patients.
Conclusions: . We propose that a histological criterion be used in combination with the degree of proteinuria as an indication for ST in adult IgAN patients.