Validation of a survival benefit estimator tool in a cohort of European kidney transplant recipients

Abstract

Pre-transplant prognostic scores help to optimize donor/recipient allocation and to minimize organ discard rates. Since most of these scores come from the US, direct application in non-US populations is not advisable. The Survival Benefit Estimator (SBE), built upon the Estimated Post-Transplant Survival (EPTS) and the Kidney Donor Profile Index (KDPI), has not been externally validated. We aimed to examine SBE in a cohort of Spanish kidney transplant recipients. We designed a retrospective cohort-based study of deceased-donor kidney transplants carried out in two different Spanish hospitals. Unadjusted and adjusted Cox models were applied for patient survival. Predictive models were compared using Harrell's C statistics. SBE, EPTS and KDPI were independently associated with patient survival (p ≤ 0.01 in all models). Model discrimination measured with Harrell's C statistics ranged from 0.57 (KDPI) to 0.69 (SBE) and 0.71 (EPTS). After adjustment, SBE presented similar calibration and discrimination power to that of EPTS. SBE tended to underestimate actual survival, mainly among high EPTS recipients/high KDPI donors. SBE performed acceptably well at discriminating post-transplant survival in a cohort of Spanish deceased-donor kidney transplant recipients, although its use as the main allocation guide, especially for high KDPI donors or high EPTS recipients requires further testing.

Figure 1

Flow chart of patients included in the study.

Figure 2

Distribution of donors and recipients according to KDPI and EPTS scores.

Figure 3

Comparison of post-transplant predicted vs actual survival according to SBE quintile distribution (1: worst; 5: best). X²(Q1 vs Q2): 1.416, P = 0.234; X²(Q2 vs Q3): 2.804, P = 0.094; X²(Q3 vs Q4): 6.606, P = 0.01; X²(Q4 vs Q5): 2.604, P = 0.107.