Early Effect of the Circular Model of Kidney Allocation in the United States

A Transplant-Inclusive Value-Based Kidney Care Payment Model

In the United States, kidney care payment models are migrating toward value-based care (VBC) models incentivizing quality of care at lower cost. Current kidney VBC models will continue through 2026. We propose a future transplant-inclusive VBC (TIVBC) model designed to supplement current models focusing on patients with advanced chronic kidney disease (CKD) and end-stage kidney disease (ESKD). The proposed TIVBC is structured as an episode-of-care model with risk-based reimbursement for "referral/evaluation/waitlisting" (REW, referencing kidney transplantation), "primary hospitalization to 180 days posttransplant," and "long-term graft survival." Challenges around organ acquisition costs, adjustments to quality metrics, and potential criticisms of the proposed model are discussed. We propose next steps in risk-adjustment and cost-prediction to develop as an end-to-end, TIVBC model.

Organ Nonutilization Following Revision to the Public Health Service Donor Risk Criteria for HIV, HCV, or HBV Transmission

BACKGROUND

Organs from Public Health Service criteria (PHSC) donors, previously referred to as PHS infectious-risk donors, have historically been recovered but not used, traditionally referred to as "discard," at higher rates despite negligible risk to recipients. On March 1, 2021, the definition of PHSC donors narrowed to include only the subset of donors deemed to have meaningfully elevated risk in the current era of improved infectious disease testing.

METHODS

Using Scientific Registry of Transplant Recipients data from May 1, 2019, to December 31, 2022, we compared rates of PHSC classification and nonutilization of PHSC organs before versus after the March 1, 2021, policy change among recovered decedents using the χ 2 tests. We performed an adjusted interrupted time series analysis to examine kidney and liver recovery/nonuse (traditionally termed "discard") and kidney, liver, lung, and heart nonutilization (nonrecovery or recovery/nonuse) prepolicy versus postpolicy.

RESULTS

PHSC classification dropped sharply from 24.5% prepolicy to 15.4% postpolicy ( P  < 0.001). Before the policy change, PHSC kidney recovery/nonuse, liver nonuse, lung nonuse, and heart nonuse were comparable to non-PHSC estimates (adjusted odds ratio: kidney =  0.98 1.06 1.14 , P  = 0.14; liver =  0.85 0.92 1.01 , P  = 0.07; lung =  0.91 0.99 1.08 , P  = 0.83; heart =  0.89 0.97 1.05 , P  = 0.47); following the policy change, PHSC kidney recovery/nonuse, liver nonuse, lung nonuse, and heart nonuse were lower than non-PHSC estimates (adjusted odds ratio: kidney =  0.77 0.84 0.91 , P  < 0.001; liver =  0.77 0.84 0.92 , P  < 0.001; lung =  0.74 0.81 0.90 , P  < 0.001; heart =  0.61 0.67 0.73 , P  < 0.001).

CONCLUSIONS

Even though PHSC donors under the new definition are a narrower and theoretically riskier subpopulation than under the previous classification, PHSC status appears to be associated with a reduced risk of kidney and liver recovery/nonuse and nonutilization of all organs. Although historically PHSC organs have been underused, our findings demonstrate a notable shift toward increased PHSC organ utilization.

Calibration of Priority Points for Sensitization Status of Kidney Transplant Candidates in the United States

Key Points

There are multiple factors associated with high sensitization levels among kidney transplant candidates, which differ by candidate sex. Since the initiation of the kidney allocation system, candidates with higher sensitization have higher rates of deceased donor transplantation. Priority points assigned to candidates associated with sensitization have led to inequities in access to deceased donor transplantation.

Background

A primary change to the national organ allocation system in 2014 for deceased donor kidney offers was to weight candidate priority on the basis of sensitization (i.e ., calculated panel reactive antibody percentage [cPRA%]) using a sliding scale. Increased priority for sensitized patients could improve equity in access to transplantation for disadvantaged candidates. We sought to evaluate the effect of these weights using a contemporary cohort of adult US kidney transplant candidates.

Methods

We used the national Scientific Registry of Transplant Recipients to evaluate factors associated with sensitization using multivariable logistic models and rates of deceased donor transplantation using cumulative incidence models accounting for competing risks and multivariable Cox models.

Results

We examined 270,912 adult candidates placed on the waiting list between January 2016 and September 2023. Six-year cumulative incidence of deceased donor transplantation for candidates with cPRA%=80–85 and 90–95 was 48% and 53%, respectively, as compared with 37% for candidates with cPRA%=0–20. In multivariable models, candidates with high cPRA% had the highest adjusted hazards for deceased donor transplantation. There was significant effect modification such that the association of high cPRA% with adjusted rates of deceased donor transplantation varied by region of the country, sex, race and ethnicity, prior dialysis time, and blood type.

Conclusions

The results indicate that the weighting algorithm for highly sensitized candidates may overinflate the need for prioritization and lead to higher rates of transplantation. Findings suggest recalibration of priority weights for allocation is needed to facilitate overall equity in access to transplantation for prospective kidney transplant candidates. However, priority points should also account for subgroups of candidates who are disadvantaged for access to donor offers.

Kidney Transplant Outcomes From Deceased Donors Who Received Dialysis

Importance

Recipient outcomes after kidney transplant from deceased donors who received dialysis prior to kidney donation are not well described.

Objective

To compare outcomes of transplant recipients who received kidneys from deceased donors who underwent dialysis prior to kidney donation vs recipients of kidneys from deceased donors who did not undergo dialysis.

Design, Setting, and Participants

A retrospective cohort study was conducted including data from 58 US organ procurement organizations on deceased kidney donors and kidney transplant recipients. From 2010 to 2018, 805 donors who underwent dialysis prior to kidney donation were identified. The donors who underwent dialysis prior to kidney donation were matched 1:1 with donors who did not undergo dialysis using a rank-based distance matrix algorithm; 1944 kidney transplant recipients were evaluated.

Exposure

Kidney transplants from deceased donors who underwent dialysis prior to kidney donation compared with kidney transplants from deceased donors who did not undergo dialysis.

Main Outcomes and Measures

The 4 study outcomes were delayed graft function (defined as receipt of dialysis by the kidney recipient ≤1 week after transplant), all-cause graft failure, death-censored graft failure, and death.

Results

From 2010 to 2018, 1.4% of deceased kidney donors (805 of 58 155) underwent dialysis prior to kidney donation. Of these 805 individuals, 523 (65%) donated at least 1 kidney. A total of 969 kidneys (60%) were transplanted and 641 kidneys (40%) were discarded. Among the donors with kidneys transplanted, 514 (mean age, 33 years [SD, 10.8 years]; 98 had hypertension [19.1%] and 36 had diabetes [7%]) underwent dialysis prior to donation and were matched with 514 (mean age, 33 years [SD, 10.9 years]; 98 had hypertension [19.1%] and 36 had diabetes [7%]) who did not undergo dialysis. Kidney transplants from donors who received dialysis prior to donation (n = 954 kidney recipients) were associated with a higher risk of delayed graft function compared with kidney transplants from donors who did not receive dialysis (n = 990 kidney recipients) (59.2% vs 24.6%, respectively; adjusted odds ratio, 4.17 [95% CI, 3.28-5.29]). The incidence rates did not significantly differ at a median follow-up of 34.1 months for all-cause graft failure (43.1 kidney transplants per 1000 person-years from donors who received dialysis prior to donation vs 46.9 kidney transplants per 1000 person-years from donors who did not receive dialysis; adjusted hazard ratio [HR], 0.90 [95% CI, 0.70-1.15]), for death-censored graft failure (22.5 vs 20.6 per 1000 person-years, respectively; adjusted HR, 1.18 [95% CI, 0.83-1.69]), or for death (24.6 vs 30.8 per 1000 person-years; adjusted HR, 0.76 [95% CI, 0.55-1.04]).

Conclusions and Relevance

Compared with receiving a kidney from a deceased donor who did not undergo dialysis, receiving a kidney from a deceased donor who underwent dialysis prior to kidney donation was associated with a significantly higher incidence of delayed graft function, but no significant difference in graft failure or death at follow-up.

Optimizing the kidney donor pool: transplanting donor kidneys after partial nephrectomy of masses or cysts

Background

A limiting factor in expanding the kidney donor pool is donor kidneys with renal tumors or cysts. Partial nephrectomy (PN) to remove these lesions prior to transplantation may help optimize organ usage without recurrence of malignancy or increased risk of complications.

Methods

We retrospectively analyzed all recipients of a living or deceased donor graft between February 2009 and October 2022 in which a PN was performed prior to transplant due to the presence of one or more concerning growths. Donor and recipient demographics, perioperative data, donor allograft pathology, and recipient outcomes were obtained.

Results

Thirty-six recipients received a graft in which a PN was performed to remove suspicious masses or cysts prior to transplant. Majority of pathologies turned out to be a simple renal cyst (65%), followed by renal cell carcinoma (15%), benign multilocular cystic renal neoplasm (7.5%), angiomyolipoma (5%), benign renal tissue (5%), and papillary adenoma (2.5%). No renal malignancy recurrences were observed during the study period (median follow-up: 67.2 months). Fourteen complications occurred among 11 patients (30.6% overall) during the first 6mo post-transplant. Mean eGFR (± standard error) at 36 months post-transplant was 51.9 ± 4.2 ml/min/1.73 m2 (N = 23). Three death-censored graft losses and four deaths with a functioning graft and were observed.

Conclusion

PN of renal grafts with suspicious looking masses or cysts is a safe option to optimize organ usage and decrease the kidney non-use rate, with no observed recurrence of malignancy or increased risk of complications.

Cold Ischemia Time and Delayed Graft Function in Kidney Transplantation: A Paired Kidney Analysis

BACKGROUND

We aimed to understand the association between cold ischemia time (CIT) and delayed graft function (DGF) after kidney transplantation and the impact of organ pumping on that association.

METHODS

Retrospective cohort study using US registry data. We identified kidney pairs from the same donor where both kidneys were transplanted but had a CIT difference >0 and ≤20 h. We determined the frequency of concordant (both kidneys with/without DGF) or discordant (only 1 kidney DGF) DGF outcomes. Among discordant pairs, we computed unadjusted and adjusted relative risk of DGF associated with longer-CIT status, when then repeated this analysis restricted to pairs where only the longer-CIT kidney was pumped.

RESULTS

Among 25 831 kidney pairs included, 71% had concordant DGF outcomes, 16% had only the longer-CIT kidney with DGF, and 13% had only the shorter-CIT kidney with DGF. Among discordant pairs, longer-CIT status was associated with a higher risk of DGF in unadjusted and adjusted models. Among pairs where only the longer-CIT kidney was pumped, longer-CIT kidneys that were pumped had a lower risk of DGF than their contralateral shorter-CIT kidneys that were not pumped regardless of the size of the CIT difference.

CONCLUSIONS

Most kidney pairs have concordant DGF outcomes regardless of CIT difference, but even small increases in CIT raise the risk of DGF. Organ pumping may mitigate and even overcome the adverse consequences of prolonged CIT on the risk of DGF, but prospective studies are needed to better understand this relationship.

UNOS Decisions Impact Data Integrity of the OPTN Data Registry

BACKGROUND

The Organ Procurement Transplant Network (OPTN)/United Network for Organ Sharing (UNOS) registry is an important national registry in the field of solid organ transplantation. Data collected are mission critical, given its role in organ allocation prioritization, program performance monitoring by both the OPTN and the Centers for Medicare & Medicaid Services, and countless observational analyses that helped to move the field forward. Despite the multifaceted importance of the OPTN/UNOS database, there are clear indications that investments in the database to ensure the quality and reliability of the data have been lacking.

METHODS

This analysis outlines 2 examples: (1) primary diagnosis for patients who are receiving a second transplant and (2) reporting peripheral vascular disease in kidney transplantation to illustrate the extensive challenges facing the veracity and integrity of the OPTN/UNOS database today.

RESULTS

Despite guidance that repeat kidney transplant patients should be coded as "retransplant/graft failure" rather than their native kidney disease, only 59% of new incident patients are coded in this manner. Peripheral vascular disease prevalence more than doubled in a 20-y span when the variable became associated with risk adjustment.

CONCLUSIONS

This article summarizes critical gaps in the OPTN/UNOS database, and we bring forward ideas and proposals for consideration as a path toward improvement.

Evaluation of Opening Offers Early for Deceased Donor Kidneys at Risk of Nonutilization

BACKGROUND

Reducing nonutilization of kidneys recovered from deceased donors is a current policy concern for kidney allocation in the United States. The likelihood of nonutilization is greater with a higher kidney donor risk index (KDRI) offer. We examine how opening offers for organs with KDRI >1.75 to the broader waitlist at varying points of time affects usage rates.

METHODS

We simulate kidney allocation using data for January 2018 to June 2019 from Organ Procurement and Transplantation Network. For the simulation experiment, allocation policy is modified so that KDRI >1.75 organs are offered to all local candidates (same donation service area) after a set amount of cold time simultaneously. Open offers to candidates nationally are similarly examined.

RESULTS

Simulation results ( n =50 replications) estimate that opening offers locally for KDRI >1.75 after 10 hours yields a nonutilization rate of 38% (range: 35%-42%), less than the prevailing rate of 55% of KDRI >1.75 kidneys. Opening offers after 5 hours yields 30% (range: 26%-34%), reducing the prevailing nonutilization rate by 45%. Opening offers nationally after 10 and 5 hours yields nonutilization rates of 11% (range: 8%-15%) and 6% (range: 4%-9%) for KDRI >1.75 kidneys, respectively.

CONCLUSIONS

Simulation findings indicate that opening offers and adjusting their timing can significantly reduce nonutilization of high-KDRI kidneys.

Deceased donor kidneys from higher distressed communities are significantly less likely to be utilized for transplantation

The proportion of kidneys procured for transplantation but not utilized exceeds 20% in the United States. Factors associated with nonutilization are complex, and further understanding of novel causes are critically important. We used the national Scientific Registry of Transplant Recipients data (2010-2022) to evaluate associations of Distressed Community Index (DCI) of deceased donor residence and likelihood of kidney nonutilization (n = 209 413). Deceased donors from higher distressed communities were younger, had an increased history of hypertension and diabetes, were CDC high-risk, and had higher terminal creatinine and donation after brain death. Mechanisms and circumstances of death varied significantly by DCI. The proportion of kidney nonutilization was 19.9%, which increased by DCI quintile (Q1 = 18.1% to Q5 = 21.6%). The adjusted odds ratio of nonutilization from the highest quintile DCI communities was 1.22 (95% CI = 1.16-1.28; reference = lowest DCI), which persisted stratified by donor race. Donors from highly distressed communities were highly variable by the donor service area (range: 1%-51%; median = 21%). There was no increased risk for delayed graft function or death-censored graft loss by donor DCI but modest increased adjusted hazard for overall graft loss (high DCI = 1.05; 95% CI = 1.01-1.10; reference = lowest DCI). Results indicate that donor residential distress is associated with significantly higher rates of donor kidney nonutilization with notable regional variation and minimal impact on recipient outcomes.

Virtual crossmatch for deceased donor kidney transplantation in the United States: A survey of histocompatibility lab directors and transplant surgeons

Virtual crossmatch (VXM) is used as an alternative to or in conjunction with a cell-based physical crossmatch (PXM) for assessing HLA (human leukocyte antigen) compatibility prior to deceased donor kidney transplantation (DDKT). Data on practice patterns and perceptions regarding VXM use in the US are limited. We performed a survey of US HLA directors and transplant surgeons regarding HLA testing and crossmatch strategies. 53 (56 %) HLA directors and 68 surgeons (representing ∼ 23 % of US transplant centers) completed the survey. Both groups agreed that VXM could reduce cold ischemia time (CIT), costs and improve allocation efficiency. VXM use increased following the 2021 kidney allocation change. Reducing CIT was the primary reason for favoring VXM over PXM. Preference for VXM reduced as candidates' panel reactive antibodies increased. Regulations, program policies and limitations of HLA technology were cited as important reasons for preferring PXM over VXM. Surgeons reported similar perceptions, but findings are limited by the low response rate. Finally, half the labs reported lacking specific protocols for VXM use. In conclusion, improved HLA technology and protocols along with changes to institutional procedures and policy regulations are needed for safer expansion of VXM in DDKT.