Repeat renal biopsy improves the Oxford classification-based prediction of immunoglobulin A nephropathy outcome

Background. The prognosis of IgA nephropathy (IgAN) is very heterogeneous. Predicting the nature and the rate of the disease progression is crucial for refining patient treatment. The aim of this study was to evaluate the prognostic impact of an Oxford classification-based repeat kidney tissue evaluation to predict end-stage renal disease (ESRD). Methods. Patients with biopsy-proven primary IgAN who underwent two renal biopsies at our centre were analyzed retrospectively. Renal biopsies were scored by two pathologists blinded to the clinical data and according to the updated Oxford classification. Cox models were generated to evaluate the prognostic impact considering the Oxford classification elementary lesions from the first (Model 1) or the second (Model 2) biopsy, adjusted on clinical data at time of reevaluation. The prognostic impacts of the dynamic evolution of each elementary lesion between biopsies were also assessed through univariate and multivariate evaluation. Results. A total of 168 adult patients were included, with a median follow-up duration of 18 (range 11-24) years. The second biopsy was performed either systematically (n = 112) of forcause (n = 56), after a median time of 5.4 years. The prognostic performances of Model 2 (second biopsy) were significantly better than Model 1 (first biopsy, analysis of deviance P < 0.0001). The dynamic changes of C and T lesions were significantly associated with the progression toward ESRD after adjustment on variables from Model 2. Conclusion. Both static and dynamic Oxford-based histological evaluation offered by a repeat biopsy improves the prediction of ESRD in patients with IgAN.