IgA vasculitis nephritis: insights from kidney biopsies.

Abstract

To present findings indicating the value of kidney biopsy in assessing prognosis and guiding clinical approach to patients with IgA vasculitis nephritis (IgAVN), including a recent international study examining the value of the Oxford (MEST-C) classification. Historically, kidney biopsies with IgAVN are scored using the International Society for Kidney Diseases in Children (ISKDC) classification. However, this classification has limited prognostic value, and most biopsies fall into just two of the six ISKDC grades. There are few studies examining the clinical value of the Oxford classification, which is well documented to be predictive of kidney outcomes in IgA nephropathy, in IgAVN. However, a recent study of 361 biopsied patients with IgAVN showed that endocapillary hypercellularity (Oxford E1) predicted a subclass of patients showing initial improvement in kidney function with immunosuppressive treatment, followed by a later decline. Kidney outcome in patients with biopsied IgAVN treated with immunosuppression is determined by clinical factors and endocapillary hypercellularity. The latter is not part of the ISKDC classification and supports including MEST-C scores in biopsy reports of IgAVN. Even patients showing a good initial response to immunosuppression require long-term follow-up due to risk of subsequent kidney function decline.