Segarra A, et al. - This retrospective cohort study was performed to examine the prognostic value of C4d deposits and association with response to treatment in patients with IgA nephropathy and normal glomerular filtration rate (GFR). For patients with idiopathic IgA nephropathy and normal kidney function, C4d deposits could be one of the earliest poor prognostic variables available at the time of diagnosis. However, Cd4 solely did not correlate with the response to angiotensin blockers or corticosteroid treatment.

Methods

• A total of 190 patients with idiopathic IgA nephropathy diagnosed by kidney biopsy between 1988 and 2005, were included in this study.
• The patients presented with GFR≥80 ml/min per 1.73 m² at the time of diagnosis, and they had a paraffin-embedded kidney biopsy with 8 glomeruli available.

Results

• In this study cohort, 170 (89%) and 20 (11%) patients were >18 and <18 years old, respectively.
• The median (interquartile range) follow-up was 15 (12-22) years.
• In this study, mesangial C4d deposit prevalence was 20% (38 of 190).
• C4d-positive vs -negative patients had higher protein-to-creatinine ratio at diagnosis (median [interquartile range]: 1.94 g/g [0.9-3.1] vs 1.45 g/g [0.9-2.2]; P=0.04).
• C4d-positive patients were found to have a higher number of nephritic flares (median [range]: 1.4 [0-5] vs 0.9 [0-2]; P=0.04), had a higher protein-to-creatinine ratio (median [interquartile range]: 1.32 g/g [0.7-1.7] vs 0.89 g/g [0.1-1.3]; P < 0.01), were more prone to receive repeated treatment with corticosteroids (45% vs 24%; P < 0.01), and showed a larger reduction in eGFR (-1.6 vs -0.8 ml/min per 1.73 m² per year; P=0.04) during follow-up.
• It was determined that the independent predictor of long-term kidney survival was presence of mesangial C4d deposits.