Not All Histological Damage in Baseline Biopsies Is Deleterious for Renal Allograft Survival

Abstract

Introduction: The impact of baseline histology and of the individual histological lesions at time of transplantation on long-term graft survival is not well known. Methods: All kidney recipients who were transplanted between 1991 and 2009, and who underwent a baseline biopsy at time of transplantation, were included in this prospective study (N=548). These biopsies were not used to guide kidney allocation. All baseline biopsies were rescored according to the current updated Banff classification. The relationship between the individual histological lesions was assessed using hierarchical clustering and principal component analysis. Survival analysis was performed using Cox proportional hazards analysis and log-rank testing. Mean follow-up time was 6.7±3.3 years. Results: Interstitial fibrosis (ci; p=0.0001), tubular atrophy (ct; p=0.05) and glomerulosclerosis (gs; p< 0.0001) predict death-censored graft survival, while arteriolar hyalinosis (ah; p=0.4) and vascular intimal thickening (cv; p=0.9) did not. Donor age proved to be a highly significant explanatory factor for ci, ct and gs (p=0.0001) and is independently associated with graft survival. Donor age did not correlate with ah (p=0.08) and cv (p= 0.1). In principal component analysis, we confirmed the dichotomy in the histological lesions at baseline, and the association with donor age (Figure A). Based on these findings, a novel scoring system for prediction of 10-year graft survival was calculated by using logistic regression analysis. This score predicted death-censored graft survival (p=0.0004) better than previously proposed and often used scoring systems (Remuzzi score p=0.03); Pirani score p=0.01).Figure: [Graphs]Conclusion: There is a clear dichotomy between the histological lesions in baseline biopsies. While age-associated lesions are highly significantly associated with graft survival, arteriolar hyalinosis and atherosclerosis in donor biopsies are not associated with survival. This dichotomy should be taken into account when evaluating baseline biopsies for kidney allocation and in algorithms to predict transplantation outcome.