IgA nephropathy: an update.

Purpose of review To provide an update on recent developments since the publication of the Oxford Classification of IgA nephropathy and to consider lesions that were not included in the original classification. Recent findings Over 20 validation studies of the Oxford Classification have been published. Tubular atrophy/interstitial fibrosis is consistently the strongest predictor of renal survival, whereas mesangial hypercellularity predicts rate of loss of renal function. Endocapillary hypercellularity and crescents are associated with lower renal survival and more rapid loss of renal function in patients not receiving immunosuppression, whereas crescents in at least 25% of glomeruli predict lower renal survival irrespective of treatment; a C score has been added to the MEST scores in the 2016 revision of the classification. Repeat biopsy studies have demonstrated response of endocapillary and extracapillary hypercellularity to immunosuppression. Podocytopathic changes in segmental sclerosis are associated with higher levels of proteinuria, renal function decline and worse renal survival. Combination of histological and clinical variables allow for earlier outcome prediction. Summary Recent evidence supports the use of the Oxford Classification of IgA nephropathy in wider populations. Combination of histological, clinical and biomarker data promises more accurate prognostication and identification of patients who will benefit from immunosuppression.