Chronic allograft nephropathy - biopsy findings and outcome

Background. Chronic allograft nephropathy (CAN) is a composite term for var ious types of damage to a kidney transplant. We wanted to analyse its compo nents in relation to baseline biopsy findings, transplant function, and out come. Methods. Among renal transplantations performed from 1985 to 1997, 156 were identified where allograft biopsies had been obtained on clinical indicati on 6 months after transplantation or later, baseline biopsies were availabl e in each case and the patient's original disease was known. Time after tra nsplantation was median 2.2 years (range 0.5-13). The biopsies were reviewe d and the Banff 1997 CAN score obtained. Results. All but one late biopsy showed some CAN grade, 48% grade II, and 7 .5% grade III. Acute tubulointerstitial rejection was seen in 9% but vascul ar rejection in only 3%. Arterial wall thickening was present in 66% of the late biopsies, correlated with donor age and its presence at baseline but also with time after transplantation. The Banff CAN score and serum creatin ine level were both independent predictors of further graft survival, relat ive risk 0.35 (confidence interval 0.15-0.82. P = 0.015) for CAN grade I vs III and 0.30 (0.14-0.67 P = 0.003) for serum creatinine < 170 vs > 250 mu mol/l. Presence of arterial wall thickening had no prognostic impact. Conclusion. The CAN grade is predictive of further graft survival independe ntly of the serum creatinine level. Interstitial fibrosis and tubular atrop hy are more prominent features of chronic graft damage than vascular reject ion. Unspecific arterial wall thickening is partly dependent on baseline co nditions and lacks prognostic impact in this late stage.