Computerized image analysis of sirius red-stained renal allograft biopsies as a surrogate marker to predict long-term allograft function

Chronic allograft nephropathy (CAN) is a major problem in posttransplant management. The lack of a reliable and early surrogate marker of CAN has hampered patient care and research. In this study, the Cortical Fractional Interstitial Fibrosis Volume (V-IntFib), quantitated with computerized image analysis of Sirius Red-stained protocol biopsies, was examined as a potential surrogate for time to graft failure (TTGF) in 68 renal allograft recipients. At 6 mo posttransplant, V-IntFib was highly correlated with TTGF (r = 0.64, P < 0.001). Both the Banff Chronic Sum and the Acute Sum Scores were also correlated with TTGF, but less strongly (r = 0.28, P < 0.02; r = 0.35, P < 0.003, respectively). As V-IntFib was not correlated with the Banff Chronic Score, a multivariate model was created that incorporated V-IntFib and both Acute and Chronic Banff pathology. This model was highly correlated with TTGF (r = 0.7, P < 0.0001). These findings suggest that V-IntFib determined by computerized image analysis of Sirius Red-stained protocol biopsies at 6 mo posttransplant, with or without incorporation of Banff acute and chronic scoring, may provide an early surrogate for time to graft failure in renal allograft recipients.