The combination of area under the curve and percentage change in estimated glomerular filtration rate predicts long-term outcome of kidney transplants

The development of surrogate markers for long-term outcomes of kidney transplant (KT) is a focus of attention. We examined the possibility of using a combination of the area under the curve of estimated glomerular filtration rate (eGFR) for 2 years (AUC_eGFR2yrs) and percent change in eGFR between 1 and 2 years after KT (% change_eGFR1/2yr) as a surrogate marker. We compared the predictive power of death-censored graft failure with various combinations. The combination of >2% vs ≤2% for % change_eGFR1/2yr and >1300 vs ≤1300 mL/min/month for AUC_eGFR2yr had the highest Harrell C-index (0.647; 95% confidence interval [95% CI], 0.604-0.690). The death-censored graft survival rate of the group with ≤2% change_eGFR1/2yr and ≤1300 mL/min/month AUC_eGFR2yr was significantly lower than those of other groups. The AUC/% change eGFR had comparable predictive power to the previously identified marker ≥30% decline in eGFR between years 1 and 3 after KT (≤−30% change_eGFR1/3yr) (Harrell's C-index = 0.645 [95% CI 0.628-0.662] for ≤−30% change_eGFR1/3yr). The proposed combination might be useful as a surrogate marker in KT trials because it requires a shorter surveillance period than the established marker while having comparable predictive power.