Scientific Registry of Transplant Recipients program-specific reports: where we have been and where we are going

Kidney transplant in the next decade: Strategies, challenges and vision of the future

Although the results of kidney transplantation (KT) have improved substantially in recent years, a chronic and inexorable loss of grafts mainly due to the death of the patient and chronic dysfunction of the KT, continues to be observed. The objectives, thus, to optimize this situation in the next decade are fundamentally focused on minimizing the rate of kidney graft loss, improving patient survival, increasing the rate of organ procurement and its distribution, promoting research and training in health professionals and the development of scientific registries providing clinical and reliable information that allow us to optimize our clinical practice in the field of KT. With this perspective, this review will deep into: (1) strategies to avoid chronic dysfunction and graft loss in the medium and long term; (2) to prolong patient survival; (3) strategies to increase the donation, maintenance and allocation of organs; (4) promote clinical and basic research and training activity in KT; and (5) the analysis of the results in KT by optimizing and merging scientific registries.

Does anybody really know what (the kidney median waiting) time is?

The median waiting time (MWT) to deceased donor kidney transplant is of interest to patients, clinicians, and the media but remains elusive due to both methodological and philosophical challenges. We used Organ Procurement and Transplantation Network data from January 2003 to March 2022 to estimate MWTs using various methods and timescales, applied overall, by era, and by candidate demographics. After rising for a decade, the overall MWT fell to 5.19 years between 2015 and 2018 and declined again to 4.05 years (April 2021 to March 2022), based on the Kaplan-Meier method applied to period-prevalent cohorts. MWTs differed markedly by blood type, donor service area, and pediatric vs adult status, but to a lesser degree by race/ethnicity. Choice of methodology affected the magnitude of these differences. Instead of waiting years for an answer, reliable kidney MWT estimates can be obtained shortly after a policy is implemented using the period-prevalent Kaplan-Meier approach, a theoretical but useful construct for which we found no evidence of bias compared with using incident cohorts. We recommend this method be used complementary to the competing risks approach, under which MWT is often inestimable, to fill the present information void concerning the seemingly simple question of how long it takes to get a kidney transplant in the United States.

Assessment of donor quality and risk of graft failure after liver transplantation: The ID2 EAL score

Accurate assessment of donor quality at the time of organ offer for liver transplantation candidates may be inadequately captured by the donor risk index (DRI). We sought to develop and validate a novel objective and simple model to assess donor risk using donor level variables available at the time of organ offer. We utilized national data from candidates undergoing primary LT (2013-2019) and assessed the prediction of graft failure 1 year after LT. The final components were donor Insulin-dependent diabetes mellitus, Donor type (DCD or DBD), cause of Death = CVA, serum creatinine, Age, height, and weight (length). The ID² EAL score had better discrimination than DRI using bootstrap corrected concordant index over time, especially in the current era. We explored donor-recipient matching. Relative risk of graft failure ranged from 1.15 to 3.5 based on relevant donor-recipient matching by the ID² EAL score. As an example, for certain recipients, a young DCD donor offer was preferable to an older DBD with relevant comorbidities. The ID² EAL score may serve as an important tool for patient discussion about donor risk and decisions regarding offer acceptance. In addition, the score may be preferable to succinctly capture donor risk in future organ allocation that considers continuous distribution (www.iddealscore.com).

Textbook Outcome as a Quality Metric in Living and Deceased Donor Kidney Transplantation

BACKGROUND

Quality in kidney transplantation is measured using 1-year patient and graft survival. Because 1-year patient and graft survival exceed 95%, this metric fails to measure a spectrum of quality. Textbook outcomes (TO) are a composite quality metric offering greater depth and resolution. We studied TO after living donor (LD) and deceased donor (DD) kidney transplantation.

STUDY DESIGN

United Network for Organ Sharing data for 69,165 transplant recipients between 2013 and 2017 were analyzed. TO was defined as patient and graft survival of 1 year or greater, 1-year glomerular filtration rate of greater than 40 mL/min, absence of delayed graft function, length of stay of 5 days or less, no readmissions during the first 6 months, and no episodes of rejection during the first year after transplantation. Bivariate analysis identified characteristics associated with TO, and covariates were incorporated into multivariable models. Five-year conditional survival was measured, and center TO rates were corrected for case complexity to allow center-level comparisons.

RESULTS

The national average TO rates were 54.1% and 31.7% for LD and DD transplant recipients. The hazard ratio for death at 5 years for recipients who did not experience TO was 1.92 (95% CI 1.68 to 2.18, p ≤ 0.0001) for LD transplant recipients and 2.08 (95% CI 1.93 to 2.24, p ≤ 0.0001) for DD transplant recipients. Center-level comparisons identify 18% and 24% of centers under-performing in LD and DD transplantation. High rates of TO do not correlate with transplantation center volume.

CONCLUSION

Kidney transplant recipients who experience TO have superior long-term survival. Textbook outcomes add value to the current standards of 1-year patient and graft survival.

A Composite End Point of Graft Status and eGFR at 1 Year to Improve the Scientific Registry of Transplant Recipients' Five-Tier Rating System

BACKGROUND

Performance of kidney transplant programs in the United States is monitored and publicly reported by the Scientific Registry of Transplant Recipients (SRTR). With relatively few allograft failure events per program and increasing homogeneity in program performance, quantifying meaningful differences in program competency based only on 1-year survival rates is challenging.

METHODS

We explored whether the traditional end point of allograft failure at 1 year can be improved by incorporating a measure of allograft function (i.e., eGFR) into a composite end point. We divided SRTR data from 2008 through 2018 into a training and validation set and recreated SRTR tiers, using the traditional and composite end points. The conditional 5-year deceased donor allograft survival and 5-year eGFR were then assessed using each approach.

RESULTS

Compared with the traditional end point, the composite end point of graft failure or eGFR <30 ml/min per 1.73 m² at 1-year post-transplant performed better in stratifying transplant programs based on long-term deceased donor graft survival. For tiers 1 through 5 respectively, the 5-year conditional graft survival was 72.9%, 74.8%, 75.4%, 77.0%, and 79.7% using the traditional end point and 71.1%, 74.4%, 76.9%, 77.0%, and 78.4% with the composite end point. Additionally, with the five-tier system derived from the composite end point, programs in tier 3, tier 4, and tier 5 had significantly higher mean eGFRs at 5 years compared with programs in tier 1. There were no significant eGFR differences among tiers derived from the traditional end point alone.

CONCLUSIONS

This proof-of-concept study suggests that a composite end point incorporating allograft function may improve the post-transplant component of the five-tier system by better differentiating between transplant programs with respect to long-term graft outcomes.

Listing at non-local transplant centers is associated with increased access to deceased donor kidney transplantation

The ability of kidney transplant candidates to travel outside of their usual place of care varies by sociodemographic factors, potentially exacerbating disparities in access. We used Transplant Referral Regions (TRRs) to overcome previous methodological barriers of using geographic distance to assess the characteristics and outcomes of patients listed for kidney transplant at centers in neighboring TRR or beyond neighboring TRRs. Among listed kidney transplant candidates, 20.9% traveled to a neighbor and 5.6% beyond a neighbor. A higher proportion of travelers were White, had some college education, and lived in ZIP codes with lower poverty. Travel to a neighbor was associated with a 7% increase in likelihood of deceased donor transplant (cHR: 1.07, 95% CI: 1.05, 1.09) and traveling beyond a neighbor with a 19% increase (cHR: 1.19, 95% CI: 1.15, 1.24). Travelers had similar rates of living donor transplant and waitlist mortality as patients who did not travel; those who traveled beyond a neighbor had slightly lower posttransplant mortality (HR: 0.91, 95% CI: 0.83, 0.99). In conclusion, the ability to travel outside of the recipient's assigned TRR increases access to transplantation and improves long-term survival.

Posttransplant outcome assessments at listing: Long-term outcomes are more important than short-term outcomes

Posttransplant outcome assessments are publicly reported for patient and regulatory use. However, the currently reported 1-year posttransplant graft survival assessments are commonly criticized for not identifying clinically meaningful differences between programs, and not providing information about longer-term posttransplant outcomes. We investigated the association of different posttransplant outcome assessments available to patients at the time of listing with subsequent posttransplant graft survival. The posttransplant assessments were from period prevalent, rather than incident, cohorts with more timely 1-, 3-, and 5-year follow-up and 6-, 12-, 18-, 24-, and 30-month cohort windows. The association of these assessments at listing with subsequent posttransplant graft survival included candidates listed between July 12, 2011, and December 15, 2015, who subsequently underwent transplant before December 31, 2018. The assessments with 1-year follow-up had uniformly weaker associations than the assessments with 3- and 5-year follow-up. The assessments with 5-year follow-up had the strongest association in kidney and liver transplantation. For kidney, liver, and lung transplantation, assessment windows of at least 18 months typically had the strongest associations with subsequent graft survival. Posttransplant assessments with 5-year follow-up and 18-30-month cohort windows are better than the current posttransplant assessment with 1-year follow-up, particularly at the time of listing.