International IgA nephropathy network clinico-pathological classification of IgA nephropathy.

There is no international consensus for the pathological or clinical classification of IgA nephropathy (IgAN). This has limited international comparisons between outcome studies which use different histological classifications, and made it more difficult to identify appropriate patients to enter into clinical intervention trials, as well as making it harder to choose appropriate therapy in individual patients. The International IgA Nephropathy Network (www.igan-world.org), working with members of the Renal Pathology Society, has established an international working group which is developing a consensus classification. Agreement has been reached on definitions of pathological features, and the consistency of scoring these features has been tested by pathologists around the world. Pathological features are now being scored in biopsies from large cohorts of patients from many parts of the world in whom sequential clinical information is available. From the integrated analysis of these clinical and pathological features, a clinico-pathological classification will be proposed which will be further refined and tested in additional cohorts of patients. The goal is to establish a reproducible and clinically effective classification which will gain worldwide acceptance for use in clinical practice and research.