External validation of the estimated posttransplant survival score for allocation of deceased donor kidneys in the United States

Abstract

The US kidney allocation system adopted in 2013 will allocate the best 20% of deceased donor kidneys (based on the kidney donor risk index [KDRI]) to the 20% of waitlisted patients with the highest estimated posttransplant survival (EPTS). The EPTS has not been externally validated, raising concerns as to its suitability to discriminate between kidney transplant candidates. We examined EPTS using data from the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. We included 4983 adult kidney-only deceased donor transplants over 2000–2011. We constructed three Cox models for patient survival: (i) EPTS alone; (ii) EPTS plus donor age, hypertension and HLA-DR mismatch; and (iii) EPTS plus log(KDRI). All models demonstrated moderately good discrimi- nation, with Harrell’s C statistics of 0.67, 0.68 and 0.69, respectively. These results are virtually identical to the internal validation that demonstrated a c-statistic of 0.69. These results provide external validation of the EPTS as a moderately good tool for discriminating posttransplant survival of adult kidney-only transplant recipients.