Remission of Proteinuria Improves Prognosis in IgA Nephropathy

TLDR

Proteinuria is an adverse prognostic factor in IgA nephropathy, yet the benefit of achieving partial remission remains poorly characterized. The study followed 542 biopsy‑confirmed IgA nephropathy patients from the Toronto Glomerulonephritis Registry, observing an average GFR decline of −0.38 ml/min/1.73 m² per month and 30 % progressing to end‑stage renal disease. During follow‑up, proteinuria was the strongest predictor of GFR decline; patients with sustained proteinuria <1 g/d experienced a 90 % slower decline, whereas those with >3 g/d lost function 25‑fold faster, and achieving partial remission in high‑proteinuria patients aligned their outcomes with low‑proteinuria patients, highlighting remission’s prognostic value.

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.