The Use of the Oxford Classification of IgA Nephropathy to Predict Renal Survival

BACKGROUND AND OBJECTIVES: A new classification for IgA nephropathy was recently proposed, namely the Oxford classification. It established specific pathologic features that predict the risk of progression of renal disease. This classification needs validation in different patient populations. We propose a retrospective study to evaluate the predictive value of the Oxford classification on renal survival defined by doubling creatinine or end-stage renal disease in patients with IgA nephropathy. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We included 183 patients with primary IgA nephropathy diagnosed between 1994 and 2005. Mean follow-up time was 77 months. Doubling creatinine occurred in 20% of the patients, and end-stage renal disease occurred in 16%. The biopsies were revisited to apply the Oxford classification. The influence of pathologic features on renal survival was analyzed in univariate and multivariate models. RESULTS: In univariate time-dependent analyses, tubular atrophy/interstitial fibrosis, segmental glomerulosclerosis, and endocapillary hypercellularity strongly impacted doubling creatinine or end-stage renal disease. On the contrary, mesangial hypercellularity was not associated with renal outcome. In the multivariate model, only estimated GFR at baseline was a risk factor, pathologic lesions having no independent influence. CONCLUSIONS: We confirm the usefulness of the Oxford classification to establish the renal prognosis of patients with IgA nephropathy, although renal function at baseline seems to be of a greater importance than pathologic lesions.