Prognostic Value of Mesangial C4d Staining in IgA Nephropathy: A Tunisian Study.

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease. The main challenge in this disease is the evaluation of prognostic factors for end-stage renal disease (ESRD). The aim of our study was to assess the clinical and prognostic implications of C4d staining in primary IgAN. This was a retrospective study, including adults with primary IgAN. The study was conducted over a period of 10 years. Renal biopsies were scored according to the Oxford classification. C4d immunohistochemical staining was performed. We included 44 patients with a sex ratio of 2.6. The average age was 35.1 ± 11 years. Twenty-two patients (57%) had hypertension (HTN). The median proteinuria was 1.92 g/day. The median of the glomerular filtration rate was 47.66 mL/min/1.73 m. According to the Oxford classification, mesangial proliferation, endocapillary proliferation, glomerulosclerosis, interstitial fibrosis and/or tubular atrophy and crescents were present in 41%, 36%, 86%, 34%, and 25 % of cases, respectively. We found positive glomerular C4d staining in 25 renal biopsies (57%). Age at diagnosis, mean arterial pressure, HTN, and baseline glomerular filtration rate were not correlated with C4d staining. On the other hand, proteinuria was significantly higher in patients with C4d-positive renal biopsy. The median follow-up duration was 30.5 months. Ten patients (23%) reached ESRD. At univariate analysis, positive C4d staining in more than 25% of glomeruli in patients without C1q deposition in the immunofluorescent study was associated with ESRD. Our study confirms the prognostic value of C4d staining in primary IgAN.