Received May 1, 2007
Accepted on July 4, 2007

CLINICAL RESEARCH

Remission of Proteinuria Improves Prognosis in IgA Nephropathy

Heather N. Reich ^*1, Stéphan Troyanov , James W. Scholey ^*, Daniel C. Cattran ^*, and for the Toronto Glomerulonephritis Registry

*Division of Nephrology, University Health Network, University of Toronto, Toronto, Ontario, and Department of Medicine, Division of Nephrology, Hôpital du Sacré-Coeur de Montréal, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada

¹ To whom correspondence should be addressed. E-mail: h.reich{at}utoronto.ca.

	Abstract

Proteinuria has been shown to be an adverse prognostic factor in IgA nephropathy. The benefit of achieving a partial remission of proteinuria, however, has not been well described. We studied 542 patients with biopsy-proven primary IgA nephropathy in the Toronto Glomerulonephritis Registry and found that glomerular filtration rate (GFR) declined at -0.38 ± 0.61 ml/min per 1.73 m²/mo overall, with 30% of subjects reaching end-stage renal disease. Multivariate analysis revealed that proteinuria during follow-up was the most important predictor of the rate of GFR decline. Among the 171 patients with <1 g/d of sustained proteinuria, the rate of decline was 90% slower than the mean rate. The rate of decline increased with the amount of proteinuria, such that those with sustained proteinuria >3 g/d (n = 121) lost renal function 25-fold faster than those with <1 g/d. Patients who presented with 3 g/d who achieved a partial remission (<1 g/d) had a similar course to patients who had 1 g/d throughout, and fared far better than patients who never achieved remission. These results underscore the relationship between proteinuria and prognosis in IgA nephropathy and establish the importance of remission.