Concise semiquantitative histological scoring system for immunoglobulin A nephropathy

Aim: Immunoglobulin A nephropathy (IgAN) is a common and progressive glomerulonephritis. Histological lesions of IgAN are variable and considered as a risk factor for renal outcome. Establishing a relatively concise histological semiquantitative scoring system would be valuable in clinical practice. Methods: Renal biopsy sections of 293 patients with primary IgAN from two centres in China were reviewed. A histological scoring system was established based on multivariate survival analysis of semiquantitative histological indices, using end-stage renal disease (ESRD) as the end-point event. Results: Four indices - extracapillary glomerular activity index (exGAI), mesangial proliferation index (MsI), glomerular chronicity index (GCI) and tubulointerstitial chronicity index (TCI) - independently correlated with ESRD (relative risk (RR) = 1.16, 2.27, 1.29 and 1.80, respectively). The four indices and the sum of their scores (Total I) constituted the scoring system. Patients with exGAI of 4 or more, GCI of 4 or more, MsI of 2 or more and TCI of 2 or more were considered as having a higher risk for progression (P < 0.05). A score of 4 or more on the exGAI index could identify the patients who should be treated with immunosuppressive drugs, which showed a lower incidence of ESRD than that without (24.3% vs 52.4%, P = 0.031). Conclusion: It suggested that the present concise scoring system could serve as prognostic and therapeutic indications.