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.