Predicting long-term kidney allograft outcomes using early clinical/biomarker data could guide individualized therapy. Emerging evidence in progressive native kidney disease indicates >30% decrease in eGFR is a surrogate of impending kidney failure but data in transplant recipients is lacking. In CTOT17 we collected 5-y outcomes on the CTOT01 observational, prospective cohort and correlated 5-y graft loss/eGFR with clinical/immune monitoring data collected during CTOT01. 1- and 2-y eGFR, pretransplant IFNg ELISPOT status, 6-mo urinary CXCL9, and a decrease in eGFR by >30% 6-24 mo posttransplant, among other characteristics were correlated with 5-y eGFR using 2-tailed tests and multivariable linear regression. We had complete data on 183 subjects (of 282 CTOT01 enrollees). Mean age was 42 y, 42% were female, 25% were African American and mean 3-mo eGFR was 61 ml/min. We observed independent associations of lower 5-y eGFR with 2-y eGFR (0.71 ml/min per ml/min lower 2-year eGFR), peak PRA (0.14 ml/min per % increase) and donor age (0.46 ml/min per y increase). Pretransplant IFNg ELISPOT+ subjects without thymoglobulin induction had lower 6-mo eGFR (56 vs. 66.5 ml/min, p=0.01), but the difference was attenuated at later time points (62 vs. 68 ml/min; p=0.26 at 2 y and 54.6 vs. 59.5; p=0.45 at 5 y). 6-mo urinary CXCL9 correlated with rejection and early eGFR decrease but there was no association with 5-y eGFR. 15/114 participants (13.1%) with available data experienced a >30% eGFR decline from 6-24 mo, and they had a lower mean 5-y eGFR (38.2 vs. 59.7 ml/min; p=0.004). In multivariable linear regression, this >30% decrease in eGFR was associated with 21.3-ml/min lower 5-y eGFR after adjusting for peak PRA and donor age, and higher likelihood of chronic kidney disease >3b (66.6% vs. 24.5%; p=0.001). A higher proportion of participants with >30% decline in eGFR within 2 y had graft loss (31% vs. 4%; p<0.001). Overall, 2-y eGFR and >30% eGFR decline over 6-24 mo posttransplant, but not early immune marker status, were individually associated with lower 5-y eGFR. While additional validation is required to limit false discovery, our findings support the use of >30% eGFR decline over the initial 2 y as a surrogate for long-term kidney transplant outcomes.

CITATION INFORMATION: Faddoul G, Nadkarni G, Hricik D, Heeger P, CTOT17 Investigators A 30% Decrease in Post-kidney Transplant Estimated Glomerular Filtration Rate (eGFR) from 6 Mo-2 Y Is a Surrogate for 5 Y eGFR: Results from Clinical Trials in Organ Transplantation-(CTOT)-17. Am J Transplant. 2016;16 (suppl 3).

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