Proposal of remission criteria for IgA nephropathy

The remission criteria of immunoglobulin A (IgA) nephropathy have varied depending on the clinical study. Therefore, nephrologists cannot make a uniform assessment of treatment outcomes and the standardization of explanations of the condition is difficult in patients with IgA nephropathy. This study aims to propose clinical remission criteria for IgA nephropathy based on a nationwide opinion survey in Japan regarding IgA nephropathy remission/relapse.

This nationwide survey was sent to 312 teaching facilities of the Japanese Society of Nephrology by Progressive Renal Disease Research, Research on Intractable Disease, from the Ministry of Health, Labour and Welfare of Japan.

Valid answers were obtained from 193 facilities (61.9 %) (136 internal medicine facilities and 57 pediatric facilities), of which 134 (69.4 %) thought that both hematuria and proteinuria should be used in the remission standards. Approximately half of the survey respondents shared the opinion on standards of negative results for hematuria and proteinuria and the duration and frequency of these conditions.

In this paper, we propose a standardized set of criteria for defining IgA nephropathy remission: three consecutive negative results over a 6-month period in urinary occult blood tests; urinary sediment red blood cell count of <5/high-power field (hematuria remission); and urinary protein of <0.3 g/day (g/g Cr; proteinuria remission). Clinical remission is defined as cases with both hematuria and proteinuria remission. These consensus-based remission criteria should be verified in future studies. In the meantime, they may be useful in predicting therapeutic outcome in cases of IgA nephropathy.