Prognostic value of glomerular C3 deposition for renal outcome in patients with IgAN
During a follow-up of 105 months, the primary endpoint of the creatinine doubling from baseline occurred in 22.1% (30/136) patients. Survival curves were performed according to the Kaplan-Meier method. Proportion of renal survival (absence of creatinine doubling) were 83.3% (85/102) v.s. 61.8% (21/34) in C3low and C3high group at the end of 105-month follow-up, respectively (Figure 5A). Estimated overall survival time were 97.8 months for patients in C3low group; 81.9 months for patients in C3high group, P =0.025 (Figure 5A). The secondary endpoint of ESRD occurred in 13.2% (18/136) patients. Proportion of renal survival (absence of ESRD) were 93.1 % (95/102) v.s. 67.6% (23/34) in C3low and C3high group, respectively. Estimated overall survival time were 100.2 months for patients in C3low group; 86.5 months for patients in C3high group, P=0.002 (Figure 5B).
We then investigated whether the density of glomerular C3 deposition could independently predict poor renal survival. In a multivariate Cox regression model, renal outcome for doubling of Scr was significantly associated with serum creatinine, proteinuria and density of glomerular C3 deposition (Table 3, model 1). When the degree of Oxford-MEST lesion classification was included in a multivariate model, the higher intensity of glomerular C3 deposits remained as an independent predictor of Scr doubling (model 2). Interestingly, the results of model 3 and model 1 are exactly the same, even though there are many differences between the two variables.
By using a multivariate Cox regression analysis, the incidence for ESRD was significantly associated with serum creatinine, proteinuria and glomerular C3 density at biopsy (Table 3, model 1). When the degree of Oxford-MEST lesion classification was included in a multivariate model, the higher intensity of glomerular C3 deposits remained as an independent predictor for ESRD (model 2).
Different models depending on multivariate analyses revealed that glomerular C3 deposits, when included with clinical variables, or included with Oxford-MEST lesion classification, was an independent predictor of Scr doubling and ESRD (Table 3, 4).