The Effect of Acute Rejection Episodes According to Banff 2009 on Long-Term Outcome of Patients after Kidney Transplantation

Abstract

Background: The effect of the most recent Banff-09 classification on graft outcomes is not well described. We undertook a retrospective analysis to determine whether the time and severity of acute transplant rejection according to the Banff-09 classification are risk factors of long-term allograft survival. Methods: 409 adult patients (pts) with at least 1 episode of biopsy proven acute rejection (BPAR) were enrolled in this study. All pts received kidney transplantation (Tx) in our centre between 01.01.1996 and 31.12.2010. In retrospect all biopsies were reclassified by the most recent Banff 2009 criteria. Only the highest BPAR was documented for each recipient with more than one BPAR. All pts were divided into two groups according to the time of first BPAR episode: group early (≤12 months post Tx) vs. late, (>12 months post Tx). Graft survival and death-censored graft survival (recipient survival) analysis were performed using the Kaplan-Meier method. Results: Eight-year allograft survival and recipient survival differed significantly (p< 0.005) between early and late rejections: it was 79.9% and 84.2% in the early group vs 54.7%, 82.1% in the late group, respectively. Similarly we observed significant differences of graft survival between early and late groups for pts with borderline changes (95.3% vs 66.6%), interstitial rejection (78.0% vs 50.0%), and vascular rejection (67.2% vs 33.3%). Recipient survival was statistically different between early and late groups for patients with borderline changes (92.4% vs 87.2%), and vascular rejection (82.4% vs 66.7%). Regarding to the severity of BPAR, there were significant differences (p< 0,001) among the eight-year graft survival (borderline 84.2% vs. grade I 70.7% grade II 62.0%) and recipient survival (borderline 90.6% vs. grade I vs 84.4% grade II 80.0%). Recipients with borderline changes had similar graft and recipient survival with pts having grade IA rejection, but had better long-term graft and recipient survival than pts with grade IB and vascular rejection. Graft and recipient survival were similar between pts with interstitial rejection and vascular rejection but pts with IA rejection had higher recipient survival than IB rejection, and pts with IIA rejection had higher graft survival than IIB rejection. Conclusions: Late occurrence of acute rejection results in inferior allograft and patient survival. In addition, more severe rejections according to the most recent Banff 2009 classification are associated with a worse long-term survival.