Since 3/26/2012, the Kidney Donor Profile Index (KDPI) has been provided with all deceased-donor kidney offers, with the goal of improving the ECD indicator. Although an improved risk index may facilitate identification and transplantation of marginal yet viable kidneys, a granular percentile system may reduce provider-patient communication flexibility, paradoxically leading to more discards (“labeling effect”). We studied the discard rates of the kidneys recovered for transplantation between 3/26/2010-3/25/2012 (“ECD era”, N=28,636) and 3/26/2012-3/25/2014 (“KDPI era”, N=29,021) using SRTR data. There was no significant change in discard rate from ECD era (18.1%) to KDPI era (18.3%) among the entire population (aOR=0.971.041.10, p=0.3), or in any KDPI stratum. However, among kidneys in which ECD and KDPI indicators were discordant, “high risk” SCD kidneys (with KDPI>85) were at increased risk of discard in the KDPI era (aOR=1.071.421.89, p=0.02). Yet, recipients of these kidneys were at much lower risk of death (aRR=0.560.770.94 at 2 years post-transplant) compared to those remaining on dialysis waiting for low-KDPI kidneys. Our findings suggest that there might be an unexpected, harmful labeling effect of reporting a high KDPI for SCD kidneys, without the expected advantage of providing a more granular risk index.

Inferences about late risk of end-stage renal disease (ESRD) in live kidney donors have been extrapolated from studies averaging <10 years of follow-up. Since early postdonation ESRD (<10 years postdonation) and late postdonation ESRD (10+ years postdonation) may differ by causal mechanism, it is possible that extrapolations are misleading. To better understand postdonation ESRD, we studied patterns of common etiologies including diabetes, hypertension, and glomerulonephritis (GN)(as reported by providers) using donor-registry data linked to ESRD-registry data. Overall, 125,427 donors were observed for a median of 11.0 years (interquartile range 5.3–15.7; maximum 25). The cumulative incidence of ESRD increased from 10 events per 10,000 at 10 years postdonation to 85 events per 10,000 at 25 years postdonation (incidence rate ratio [IRR] for late vs. early ESRD [adjusted for age, race, and sex]: 1.31.72.3 [subscripts are 95% confidence intervals]). Early postdonation ESRD was predominantly reported as GN-ESRD; however, late postdonation ESRD was more frequently reported as diabetic-ESRD and hypertensive-ESRD (IRR 2.37.725.2 and 1.42.64.6). These time-dependent patterns were not seen with GN-ESRD (IRR 0.40.71.2). Since ESRD in live kidney donors has traditionally been reported in studies averaging <10 years of follow-up, our findings suggest caution in extrapolating such results over much longer intervals.

The impact of donor quality on post-kidney transplant (KT) survival may vary by candidate condition. Characterizing this variation would increase access to KT without sacrificing outcomes. We developed a tool to estimate post-KT survival for combinations of donor quality and candidate condition. We studied deceased donor KT recipients (n = 120 818) and waitlisted candidates (n = 376 272) between 2005 and 2016 by using the Scientific Registry of Transplant Recipients. Donor quality and candidate condition were measured by using the Kidney Donor Profile Index (KDPI) and the Estimated Post Transplant Survival (EPTS) score. We estimated 5-year post-KT survival based on combinations of KDPI and EPTS score using random forest algorithms and waitlist survival by EPTS score using Weibull regressions. Survival benefit was defined as absolute reduction in mortality risk with KT. For candidates with an EPTS score of 80, 5-year waitlist survival was 47.6%, and 5-year post-KT survival was 78.9% after receiving kidneys with a KDPI of 20 and was 70.7% after receiving kidneys with a KDPI of 80. The impact of KDPI on survival benefit varied greatly by EPTS score. For candidates with low EPTS scores (eg, <40), the KDPI had limited impact on survival benefit. For candidates with middle or high EPTS scores (eg, >40), survival benefit decreased with higher KDPI but was still substantial even with a KDPI of 100 (>16 percentage points). Our prediction tool (www.transplantmodels.com/kdpi-epts) can support individualized decision-making on kidney offers in clinical practice.