Glomerular crescents are not part of the Oxford classification of IgA nephropathy (IgAN), as the presence of crescents did not predict outcome in the original Oxford cohort. This initial study excluded patients with severe or rapidly progressive disease; however, subsequent studies that have used less restrictive entry criteria indicate that crescents might predict poor outcomes in certain populations. New findings show that higher numbers of crescents are associated with poorer outcomes in individuals with IgAN, suggesting that adding crescent scores to the Oxford classification might help to identify patients at increased risk of progression.

We propose adding crescent scores to the Oxford classification

To investigate the predictive value of crescents in patients with IgAN, Mark Haas and colleagues studied a cohort of 3,096 well-characterized patients from four existing studies: the original Oxford cohort, including patients from four continents; the European VALIGA study; and two Asian cohorts. “Overall, any cellular or fibrocellular crescents were independent predictors of the likelihood of developing the combined event of a ≥50% reduction in estimated glomerular filtration rate or end-stage renal disease, but this was not statistically significant in patients receiving immunosuppression,” says Haas. “However, after quantitating fractions of crescents, we found that the presence of crescents in ≥25% of glomeruli was predictive of the combined event, even in patients receiving immunosuppression.”

“Based on our findings, we propose adding crescent scores to the Oxford classification as follows: C0, no cellular or fibrocellular crescents; C1, cellular and/or fibrocellular crescents in <25% of glomeruli, identifying patients at increased risk of a poorer outcome than patients with a C0 classification if not given immunosuppressive therapy; and C2, crescents in ≥25% of glomeruli, identifying patients at increased risk of a poor outcome even if given immunosuppression,” notes Haas.