SUN-033 IMPACT OF THE PRESENCE OF CRESECENTS ON DEVELOPMENT OF END STAGE KIDNEY DISEASE IN IgA NEPHROPATHY

Abstract

Background: Oxford Classification of IgA nephropathy (IgAN) consists of the presence of 4 key pathologic features: mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental sclerosis (S) and tubular atrophy and interstitial fibrosis (T). The association between MEST score and kidney outcome has been evaluated in previous studies. More recently crescents (C) were added to Oxford classification but the impact of crescents on prediction of renal outcome is less well studied. Aim: To evaluate the impact of crescents in kidney biopsy of patients with IgAN on development of end stage kidney disease (ESKD) and its’ interaction with other elements of Oxford classification as an independent variable. One- hundred fifteen patients with primary IgAN (76% men, mean age 37±13 years, mean serum creatinine: 2.7±2.1 mg/dl, and proteinuria: 3.4±2.5 g/24 hours) were followed for 43±29 months. Pathologic findings and MEST score were defined according to Oxford classification (M0/M1, E0/E1, S0/S1), but to increase the power of study, T was defined as T0<25% and T1≥ 25%. In this study crescents (C) were defined as C0 (absence) and C1 (at least one crescents in biopsy specimen). Association between Oxford classification scores and risk of ESRD were examined by time-dependent Cox model to estimate hazard ratio (HR) with 95% CI with univariate and multivariate analyses, which was adjusted for demographics, laboratory and pathological findings. Kaplan-Meier and the log-rank tests were used to estimate kidney survival. During follow-up 40 (35%) patients developed ESKD (dialysis or kidney transplantation). 44 (38%) patients had at least one crescent and among them 25 (57%) developed ESRD. From 57 (49.5%) patients with T1, 34 (60%) developed ESKD. Twenty-nine patients had bothT1and C1 and among them, 23 (79%) developed ESKD. In the adjusted model, the presence of T1+ C1 was associated with risk of ESKD (HR: 6.75, 95% CI 2.01-22.65, P<0.001), but this association was not significant for M1+C1, E1+C1 or S1+C1 (P=0.31, P=0.62, P=0.092, respectively). The median kidney survival was 80.8 months (95% CI, 75.0-86.7 months) for patients with T0+C0 and 27.3 months (95% CI, 16.1-38.3 months) for those with T1+C1. In this study on patients with IgAN who were pathologically classified with Oxford Classification, tubular atrophy and interstitial fibrosis≥25%, or the presence of at least one crescent in biopsy specimens, were independently associated with increased risk of developing ESKD. This risk was strongly increased in the presence of both C1+T1 and 80% of such patients developed ESKD in a mean period of 27 months, despite aggressive immunosuppressive therapy.