A Predictive Clinical Grading System for Immunoglobulin A Nephropathy by Combining Proteinuria and Estimated Glomerular Filtration Rate

Abstract

Background: There is no clinical classification of immunoglobulin A nephropathy (IgAN) in clinical practice. In this study, we used receiver-operating characteristic (ROC) analysis to create accurate clinical grades based on clinical parameters associated with the development of end-stage renal disease (ESRD) in IgAN patients. Methods: We performed a retrospective analysis of 116 patients with IgAN. The association between clinical variables and progression to ESRD was examined. Results: Logistic regression analysis indicated that 24-hour urinary protein excretion (UPE) and the estimated glomerular filtration rate (eGFR) at the time of renal biopsy (RBx) were independently associated with the development of ESRD. When combining UPE and eGFR, the areas under the curve were superior to those for UPE or eGFR alone. Moreover, two-graph ROC analysis indicated that the threshold values for UPE and eGFR in predicting future ESRD were 1.0 g/day and 64.0 ml/min/1.73 m2, respectively. Of note, the patients were classified into 4 grades by levels of UPE and/or eGFR, and the OR for risk of ESRD rose significantly from grade I to grade IV. Conclusion: The combination of UPE and eGFR at the time of RBx can improve the predictive accuracy of risk for subsequent ESRD in IgAN patients.