Clinical usefulness of the Oxford classification in determining immunosuppressive treatment in IgA nephropathy

Background: The Oxford classification has been widely used in IgA nephropathy. However, its clinical usefulness of determining immunosuppression is unknown. Aim: Whether the Oxford classification could predict the development of proteinuria ≥1 g/g Cr and worsening kidney function, as well as the clinical efficacy of corticosteroid treatment according to each histologic variable of the Oxford-MEST. Methods: We included 377 patients with early-stage IgA nephropathy. The study endpoints were the development of a heavy proteinuria and a decline renal function. Results: The results showed that among the Oxford-MEST lesions, only M1 predicted the risk of the development of proteinuria ≥1.0 g/g Cr compared to other lesions in a time-varying Cox model adjusted for multiple confounding factors. In addition, the risk of reaching a 30% decline in eGFR was significantly higher in patients with M1 than in those with M0. Furthermore, patients with M1 had a greater decline of eGFR than patients with M0. However, steroid treatment in M1 lesion was not associated with improving clinical outcomes in the unmatched and propensity score matched cohort. Conclusions: This finding may provide a rationale for using the Oxford classification as a guidance to initiate immunosuppression in the early stages of IgA nephropathy.KEY MESSAGES M1 has independently predictive role among the Oxford lesions in IgA nephropathy. Oxford classification should be defined during pathologic approach. Decision of starting immunosuppression according to the Oxford lesions.