Clinical impact of endocapillary proliferation with modified cutoff points in IgA nephropathy patients

Predictive values of mesangial proliferation (M), endocapillary proliferation (E), segmental glomerulosclerosis (S), and crescents (C) among 19 validation studies of the Oxford Classification of IgA nephropathy (IgAN) were discrepant, especially in Asian patients. These validation studies indicate that cutoffs of MESC score in the Oxford Classification may not be generalizable. Thus, we aimed to improve the clinical value of MESC scores by modifying the cutoff points. A total of 104 patients with IgAN were diagnosed from 2001 to 2012 vai renal biopsy and retrospectively evaluated at Nagoya University Hospital. The cutoff point for modified (M´E´S´C´) was determined using the receiver operating characteristic curve in association with renal outcome in the training cohort. Clinical values of the Oxford MESTC vs M´E´S´C´ cutoff points were analyzed using Kaplan-Meier and Cox regression in association with poor renal outcome in the validation and the entire cohort. Of 104 patients, 12.5% reached poor renal outcome over a median of 6.25 [4.16-9.61] years of follow-up. The modified cutoffs were defined as ≥40%, ≥10%, ≥20%, and ≥5% in the glomeruli for M´E´S´, and C´ respectively. In univariate analysis, E´, S ´, and T were significantly associated with poor renal outcome, whereas Oxford MESC, M´, and C´ in the training and validation cohort were not associated with poor renal outcome. Using multivariate analysis in the presence of estimated glomerular filtration rate (eGFR), only E´ was a significant predictive factor for poor renal outcome. The E´ with modified cutoff point of 10% significantly improved predictive value for poor renal outcome in IgAN. Therefore, the clinical value of modified cutoff points for M´E´S´C´ scores should be validated with various cohort studies in different regions.