Oxford classification for IgA nephropathy was the result of rigorous methodology rather than relying purely on experts' opinion. Since its coming out in 2009 many validation studies followed. Lv et al. systematically reviewed and performed meta-analysis in 16 of
such studies with 3,896 patients included. Their findings confirmed the association of M (mesangial hypercellularity), S (segmental sclerosis) and T (tubular atrophy/interstitial fibrosis) with progression to renal failure. In addition, C (cellular/fibrocellular crescent) also had similar association (the Oxford did not include crescent in the classification/score. E (endocapillary proliferation) showed no association with renal failure but may indicate response to treatment by immunosuppressive agents.