Big data in organ transplantation: registries and administrative claims

A systematic review of reporting and handling of missing data in observational studies using the UNOS database

BACKGROUND

Missing data decreasing study power and introducing bias, thereby undermining a registry's ability to draw valid inferences. We evaluated how missing data are reported and addressed in heart transplantation (HT) studies using the United Network for Organ Sharing (UNOS) database.

METHODS

We conducted a systematic literature search of Medline from January 1, 2018 through August 22, 2023 and included studies that used the UNOS database to evaluate adult (≥18 years) de novo HT recipients. We collected details on the study population, timeframe, primary end-point, use of missing data, and whether and what methods were used to handle missing data. Approaches were classified as variable selection, complete case analysis (CCA), missing indicator method, single imputation, or multiple imputation.

RESULTS

Of the 229 included studies, 67 (29.3%) limited their cohorts to those without missing data for the outcome or key variables and 93 (40.6%) reported missing data in their final cohort. 78 (34.1%) studies reported how they handled missing data in their statistical modeling. Of these, CCA was most used (n = 41, 52.6%) followed by multiple imputation (n = 22, 28.2%), and other methods (n = 15, 19.2%). Thirty-one (13.5%) studies reported removing covariates from their analysis because of missingness.

CONCLUSIONS

Merely a third of the identified UNOS database studies reported how they handled missing data in their analysis, with strategies varying. Although no singular approach to handling missing data exists, methods are available that can improve upon the most used approaches. Future best practices should include explicit reporting of missingness, detailed methods, and sensitivity checks.

Waitlist mortality for patients with cardiac allograft vasculopathy under the 2018 OPTN donor heart allocation system

BACKGROUND

In the 2018 Organ Procurement and Transplantation Network donor heart allocation system, patients listed for re-transplantation due to cardiac allograft vasculopathy (CAV) are assigned to Status 4 unless hemodynamic criteria are met. We aim to examine waitlist outcomes of CAV patients among adult heart transplant candidates.

METHODS

We examined waitlist mortality stratified by CAV and waitlist status among adult heart transplant candidates using Scientific Registry of Transplant Recipients data from 10/1/2018-11/1/2023. We analyzed waitlist mortality using Kaplan-Meier curves and doubly-robust Cox regressions adjusted for age, gender, sex, race, and dialysis. We compared CAV to non-CAV patients by initial waitlist status, first status of interest, and time-dependent status.

RESULTS

Of 21,586 listed patients, 368 were listed for CAV. CAV patients were most often listed at Status 4 with lower proportions at Status 3/2/1 compared with non-CAV patients. Status 4 and Status 3 CAV candidates demonstrated higher than expected waitlist mortality compared to non-CAV counterparts (Status 4: HR 0.51, 95% CI 0.31-0.84; p < 0.01; Status 3: HR 0.61, 95% CI 0.23-1.64; p = 0.33) with similar mortality to non-CAV patients in Status 3 and 2, respectively (Status 4: HR 0.80, 95% CI 0.48-1.35; p = 0.4; Status 3: HR 1.07, 95% CI 0.40-2.86; p = 0.89). When stratifying by status tier, CAV waitlist patients ever listed at Status 4 and 3 had a higher probability of death compared to their non-CAV counterparts (Status 4: HR 1.99, 95% CI 1.20-3.31, p < 0.01; Status 3: HR 3.06, 95% CI 1.06-8.87, p = 0.04).

CONCLUSIONS

After 2018, CAV patients had a higher risk of waitlist mortality at Status 4 and 3 compared to non-CAV patients. These results suggest that CAV patients are underprioritized in the current allocation system.

For your consideration: Benefits of listing as willing to consider heart offers from donors with hepatitis C

BACKGROUND

Despite excellent outcomes of heart transplants from hepatitis C virus (HCV)-positive donors (D+), many candidates are not listed to even consider HCV D+ offers.

METHODS

Using the Scientific Registry of Transplant Recipients, we identified adult (age ≥18 years) heart transplant candidates prevalent on the waitlist between 2018 and March 2023. We compared the likelihood of waitlist mortality or heart transplant by candidate willingness to consider HCV D+ offers using competing risk regression.

RESULTS

We identified 19,415 heart transplant candidates, 68.9% of whom were willing to consider HCV D+ offers. Candidates willing to consider HCV D+ offers had a 37% lower risk of waitlist mortality (subhazard ratio [SHR], 0.63; 95% confidence interval [CI], 0.56-0.70; P < .001) than candidates not willing to consider HCV D+ offers, after adjustment for covariates and center-level clustering. Over the same period, heart transplant candidates willing to consider HCV D+ offers had a 21% higher likelihood of receiving a transplant (SHR, 1.21; 95% CI, 1.7-1.26; P < .001). As a result, among candidates willing to consider HCV D+ offers, 74.9% received a transplant and 6.1% died/deteriorated after 3 years, compared to 68.3% and 9.1%, respectively, of candidates not willing to consider HCV D+ offers. Lower waitlist mortality also was observed on subgroup analyses of candidates on temporary and durable mechanical circulatory support.

CONCLUSIONS

Willingness to consider HCV D+ heart offers was associated with a 37% lower risk of waitlist mortality and a 21% higher likelihood of receiving a transplant. We urge providers to encourage candidates to list as being willing to consider offers from donors with hepatitis C to optimize their waitlist outcomes and access to transplantation.

A national registry study evaluated the landscape of kidney transplantation among presumed unauthorized immigrants in the United States

Unauthorized immigrants and permanent residents may experience challenges in accessing kidney transplantation due to limited healthcare access, socioeconomic and cultural barriers. Understanding the United States (US) national landscape of kidney transplantation for non-citizens may inform policy changes. To evaluate this, we utilized two cohorts from the US national registry (2013-2023): 287,481 adult candidates for first transplant listing and 190,176 adult first transplant recipients. Citizenship was categorized as US citizen (reference), permanent resident, and presumed unauthorized immigrant. Negative binomial regression was used to quantify the incidence rate ratio over time by citizenship status. Cause-specific hazards models, with clustering at the state of listing/transplant, were used to calculate the adjusted hazard ratio of waitlist mortality, kidney transplant, and post-transplant outcomes (mortality/death-censored graft failure) by citizenship category. The crude proportion of presumed unauthorized immigrants listed increased over time (2013:0.9%, 2023:1.9%). However, after accounting for case mix and waitlist size, there was no change in listing over time. Presumed unauthorized immigrants were less likely to experience waitlist mortality (adjusted Hazard Ratio 0.54, 95% Confidence Interval: 0.46-0.62), were more likely to obtain deceased donor kidney transplant (1.11: 1.05-1.18), but less likely to receive live donor (0.80: 0.71-0.90) or preemptive kidney transplant (0.52: 0.43- 0.62). When stratified by insurance status, presumed unauthorized immigrants on Medicaid were less likely to receive deceased donor kidney transplants compared to their citizen counterparts; however, presumed unauthorized immigrants with Private insurance or Medicare were more likely to receive deceased donor kidney transplants. Presumed unauthorized immigrants were less likely to experience post-transplant death (0.56: 0.43-0.69) and graft failure (0.69: 0.57-0.84). Residents had similar pre- and post-transplant outcomes. Despite the barriers to kidney transplantation faced by presumed unauthorized immigrants and residents in the US, better post-transplant outcomes for presumed unauthorized immigrants compared to citizens persisted, even after accounting for differences in patient characteristics.

Thrombogenicity Assessment of Perfusable Tissue-Engineered Constructs: A Systematic Review

Vascular surgery is facing a critical demand for novel vascular grafts that are biocompatible and thromboresistant. This urgency is particularly applicable to bypass operations involving small caliber vessels. In the realm of tissue engineering, the development of fully vascularized organs is promising as a solution to organ shortage for transplantation. To achieve this, it is essential to (re)construct a biocompatible and nonthrombogenic vascular network within these organs. In this systematic review, we identify, classify, and discuss basic principles and methods used to perform in vitro/ex vivo dynamic thrombogenicity testing of perfusable tissue-engineered organs and tissues. We conducted a preregistered systematic review of studies published in the last 23 years according to PRISMA-P Guidelines. This comprised a systematic data extraction, in-depth analysis, and risk of bias assessment of 116 included studies. We identified shaking (n = 28), flow loop (n = 17), ex vivo (arteriovenous shunt, n = 33), and dynamic in vitro models (n = 38) as the main approaches for thrombogenicity assessment. This comprehensive review reveals a prevalent lack of standardization and provides a valuable guide in the design of standardized experimental setups.

It's Getting Better All the Time: Decreased Cumulative Incidence of Waitlist Mortality in Pediatric Candidates Following 2018 Heart Allocation Policy Change

PURPOSE

In October 2018, the OPTN changed adult heart transplant (HT) allocation policy, increasing the number of adult candidates that had higher priority than pediatric candidates, potentially disadvantaging pediatric waitlist registrants.

METHODS

To understand the impact of this policy change, we used SRTR data to identify 1469 pre-policy (7/2016-9/2018) and 2901 (10/2018-12/2022) post-policy pediatric (< 18 years) HT registrants. We quantified mortality and transplant risks using weighted cause-specific hazard models, and then using weighted competing risks regression. We further stratified these analyses by age to understand risks for those in direct competition with adults for organs (≥ 12 years).

RESULTS

Post-policy, patients were more likely to need VAD prior to HT. There were no changes in post-policy access to HT (weighted hazard ratio [wHR] = 0.96 1.03 1.11, p = 0.43). Mortality risk censoring for transplantation declined by 20% post-policy (wHR = 0.64 0.80 1.02, p = 0.05). When accounting for competing risks of transplantation, post policy, mortality decreased by 24% compared to pre-policy (weighted subdistribution HR [wSHR] = 0.61 0.76 0.94, p = 0.02). Post policy, 1-year transplant rate did not change in those < 12years (68.2%-71.0%, p = 0.77), but in those ≥ 12years, transplant rate increased (77.3%-81.0%, p = 0.003).

CONCLUSIONS

Mortality on the waitlist decreased and access to HT for pediatric registrants did not decline following the 2018 policy change. The decreased mortality rate may reflect changes in patient casemix and/or improved patient care. Continued surveillance is important in ensuring equity in pediatric, and adult, HT.

Associations Among Circle-Based Kidney Allocation, Center Waiting Time, and Likelihood of Deceased-Donor Kidney Transplantation

RATIONALE & OBJECTIVE

The kidney allocation system (KAS250), using circle-based distribution, attempts to address geographic disparities through broader sharing of deceased-donor kidney allografts. This study evaluated the association between KAS250 and likelihood of deceased-donor kidney transplantation (DDKT) among wait-listed candidates, and whether the policy has differentially affected centers with shorter versus longer waiting time.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

160,941 candidates waitlisted at 176 transplant centers between March 2017 and March 2024.

EXPOSURE

KAS250 allocation policy.

OUTCOME

Rate of DDKT.

ANALYTICAL APPROACH

Multivariable Cox regression, modeling KAS250 as a time-dependent variable.

RESULTS

KAS250 was not independently associated with likelihood of DDKT overall (HR, 1.01 vs pre-KAS250 [95% CI, 0.97-1.04]). KAS250's association with likelihood of DDKT varied across centers from HR, 0.18 (DDKT less likely after KAS250), to HR, 17.12 (DDKT more likely) and varied even among neighboring centers. KAS250 was associated with decreased DDKT at 25.6% and increased DDKT at 18.2% of centers. Centers with previously long median waiting times (57+months) experienced increased likelihood of DDKT after KAS250 (HR, 1.20 [95% CI, 1.15-1.26]) whereas centers with previously short median waiting times (6-24 months; HR, 0.88 [95% CI, 0.84-0.92]) experienced decreased likelihood of DDKT.

LIMITATIONS

Retrospective study of allocation policy changes, confounded by multiple changes over the study time frame.

CONCLUSIONS

Association between KAS250 and DDKT varied across centers. For 1 in 4 centers, DDKT was less likely after KAS250 relative to pre-KAS250 trends. Candidates at centers with previously long waiting times experienced an increased likelihood of DDKT after KAS250. Thus, broader distribution of kidneys may be associated with improved equity in access to DDKT, but additional strategies may be needed to minimize disparities between centers.

PLAIN-LANGUAGE SUMMARY

This study examines how a recent policy change, KAS250, aimed at broadening the geographic sharing of deceased-donor kidneys, has impacted likelihood of kidney transplantation in the United States. Historically, kidney allocation occurred within local geographic boundaries, leading to unequal rates of transplantation across regions. KAS250, implemented in March 2021, replaced this system with a broader allocation radius of 250 miles around the donor hospital. Using national registry data, the study found that while there was no overall significant increase in the likelihood of transplantation nationally under KAS250, the policy's effect varied widely even among neighboring transplant centers. One quarter of centers experienced a decrease in the likelihood of DDKT after KAS250. In contrast, centers with longer pre-KAS250 waiting times experienced an increased likelihood of transplantation, suggesting some success in reducing disparities between centers. Ongoing surveillance will be needed to ensure KAS250 is meeting the intended aim of more equitably distributing organs.

The Early Steps to Transplant Access Registry (E-STAR) dashboard: center-specific reporting on prewaitlisting data to improve access to kidney transplantation

PURPOSE OF REVIEW

The 2022 National Academies of Sciences, Engineering, and Medicine report highlighted inequities in access to kidney transplantation and called for a comprehensive dashboard highlighting early transplant steps, yet data on steps such as referral and evaluation start are limited. Addressing this gap is crucial for improving equity in access to transplantation.

RECENT FINDINGS

The Early Steps to Transplant Access Registry (E-STAR) provides a model for how prewaitlisting data can be used to inform quality improvement to drive equity in access to transplantation. E-STAR includes data from 37 transplant centers across 13 states and four regions (Southeast, New York, New England, and the Ohio River Valley), representing ∼217 000 adults with end-stage kidney disease (ESKD) treated in 4365 dialysis facilities, in addition to patients preemptively referred. Similar to the Scientific Registry of Transplant Recipients center-specific reports, the E-STAR dashboard was developed as an interactive website offering center-specific and regional insights into pretransplant access measures within and across centers with the intention to improve access to transplantation. Publicly available de-identified reports illustrate trends in referral, evaluation, and waitlisting by subgroup (e.g., race, sex, age, insurance status), while password-protected features enable transplant centers to benchmark their performance against anonymized peers.

SUMMARY

The E-STAR dashboard demonstrates how centralized, standardized data collection can support transplant centers, policymakers, community partners, and regional organizations to identify disparities, drive quality improvement, and develop interventions for the advancement of equity in transplant access. This work may inform future center-specific reports once prewaitlisting data are collected nationally.

Transforming transplantation access: A federal directive for comprehensive pre-waitlisting data collection

There is substantial variation in access to transplantation across the United States that is not entirely explained by the availability of donor organs. Barriers to transplantation and variation in care among patients with end-stage organ disease exist prior to patients' placement on a transplant waiting list as well as following waitlist placement. However, there are currently no national data available to examine rates and variations in key care processes related to prelisting, including transplant referral, evaluation, or candidate selection. In February of 2024, the Health Resources and Services Administration released a directive and, in November 2024, released for public comment the proposed expansion of the Organ Procurement and Transplantation Network data collection to include pre-waitlist data for all solid organ transplant patients to promote transparency across the transplant continuum. Although data elements and details have not been finalized, the purpose of this article is to detail the rationale and anticipated details for pre-waitlisting data collection to inform the transplant community. These data aim to examine care processes and barriers to care for patients with end-stage organ disease in the United States.

Long-term outcomes of corneal transplantation: a review of 8,378 patients

PURPOSE

To analyze the outcomes of corneal transplantation procedures over a 13-year period at Farabi Eye Hospital, Tehran, Iran, to identify trends and determinants influencing the frequency and success of primary and re-transplantations.

METHODS

Utilizing a comprehensive dataset from the hospital's Hospital Information System, the study reviewed the records of 8,378 patients who underwent corneal transplants between 2009 and 2022. This analysis included demographic information, surgical details, and follow-up data. Statistical methods were applied to assess the impact of variables such as age, gender, surgeon experience, and surgical techniques on the likelihood of re-transplantation.

RESULTS

Of the 8,378 transplants, 7,660 (91.4%) were primary procedures while 718 (8.6%) involved re-transplantation. The most common primary transplant was penetrating keratoplasty (PKP, 50.3%), followed by Descemet's stripping endothelial keratoplasty (DSAEK, 29.3%), and deep anterior lamellar keratoplasty (DALK, 18.5%). Analysis revealed no significant association between re-transplantation rates and patient gender or nationality. Older recipient age correlates with higher re-transplantation rates, likely due to reduced regenerative capacity and increased comorbidities in older patients. Pre-transplant comorbidities (e.g., keratoconus, ulcers), concurrent surgeries (e.g., vitrectomy), and prior procedures (e.g., glaucoma surgeries, IOL implantation) significantly increase re-transplantation risk, likely due to additional ocular stress and inflammation.

CONCLUSION

The study highlights the importance of patient age, surgeon experience, and the choice of surgical technique in the success rates of corneal transplants. These factors are crucial for optimizing patient outcomes and minimizing the necessity for re-transplantations.

Deceased Donor Renal Allograft Utility in Adult Single and Multi-organ Transplantation in the United States

Background

Deceased donor multiorgan transplants utilizing kidneys (MOTs) can improve outcomes for multiorgan recipients but reduces kidneys for chronic renal failure patients.

Methods

We reviewed the Organ Procurement and Transplantation Network database from 2015 through 2019, for adult deceased donor kidney transplants. Recipients were classified as kidney transplant alone (KTA) (n = 62,252) or MOTs pancreas-kidney, simultaneous pancreas-kidney (n = 3,976), liver-kidney, simultaneous liver-kidney (n = 3,212), heart-kidney, simultaneous heart-kidney (n = 808), and "other"-kidney, simultaneous "other" kidney (n = 73).

Results

Liver, heart, and lung-alone transplants were at least 7 times more frequent than their MOT correlate, whereas the inverse was true with pancreas transplantation with SPKs being by far the most common pancreas transplant type. On average, KTA recipients waited between 2.8 and 21.4 times longer than MOTs, with SPKs waiting the longest of the MOT types. Predialysis initiation transplants were less frequent in KTAs compared with MOTs. Use of high-quality grafts according to Kidney Donor Profile Index < 35% was frequent among MOTs, but uncommon in KTAs who had an Estimated Post Transplant Survival score (EPTS) of >20%. For recipients older than 65, SPKs and SOKs were rare, but SLKs and SHKs had a higher fraction of recipients than KTAs and were much more likely to use a Kidney Donor Profile Index <35% kidney. SPKs and KTAs with an EPTS ≤20% had the best kidney graft survival. KTAs with an EPTS ≤80% had better kidney graft survival than SLKs, SHKs, and SOKs.

Conclusions

This study highlights disparities in access to deceased donor kidneys for kidney-alone candidates versus MOTs and suggests opportunities to improve allocation.

Age-modified risk factors for mortality of non-elderly adult kidney transplant recipients: a retrospective database analysis

PURPOSE

We aimed to investigate the role of the recipient's age strata in modifying the associations between risk factors and mortality in non-elderly adult kidney transplant (KT) recipients (KTR).

METHODS

We stratified 108,695 adult KTRs between 2000 and 2016 with conditional 1-year survival after KT into cohorts based on age at transplant: 18-49 years and 50-64 years. We excluded KTRs aged < 18 years or > / = 65 years. KTRs were observed for 5 years during the 2nd through 6th years post-KT for the outcome, all-cause mortality.

RESULTS

Increasing recipient age strata (18-49-year-old and 50-64-year-old) correlated with decreasing 6-year post-KT survival rates conditional on 1-year survival (79% and 57%, respectively, p < 0.0001). Middle adult age stratum was associated with a higher risk of all-cause mortality than young adult age stratum in KTRs of Hispanic/Latino and other races [HR = 1.23, 95% CI = 1.04-1.45 and HR = 1.51, 95% CI = 1.16-1.97, respectively] and with a primary native renal diagnosis of hypertension or glomerulonephritis [HR = 1.32, 95% CI = 1.12-1.55 and HR = 1.29, 95% CI = 1.10-151, respectively]. When compared with the young adult age stratum, the middle adult age stratum had a mitigating effect on the higher risk of mortality associated with sirolimus-mycophenolate or sirolimus-tacrolimus than the standard calcineurin inhibitor-mycophenolate regimen [HR = 0.75, 95% CI = 0.57-0.99 and HR = 0.71, 95% CI = 0.57-0.89, respectively].

CONCLUSION

Among adult non-elderly KTRs, the age strata, 18-49 years, and 50-64 years, have varying modifying effects on the strength and direction of associations between some specific risk factors and all-cause mortality.

Deficits in Pre- and Post-transplant Functional, Motor, and Cognitive Deficits Associated With Graft Failure and Mortality in Pediatric Heart Transplant Recipients

BACKGROUND

Pretransplant functional, motor, cognitive, and academic deficits are common in pediatric patients requiring heart transplantation (HT); some persist post-HT. We assessed the association between these quality of life (QoL) deficits and post-HT outcomes.

METHODS

Using SRTR data 2008-2023, we evaluated the functional, motor, cognitive, and academic status of pediatric HT recipients from listing to 15 years post-HT. We compared all-cause graft survival among patients with vs. without pre-HT deficits using Cox regressions. Among patients with a functioning graft at 1 year, we assessed the association between deficits at that time and subsequent graft failure.

RESULTS

In 6153 HT recipients, 85.3% had pre-HT functional status ≤ 80%, 53.1% of patients could not tolerate a full academic load; this decreased to 15.2% and 15.0% postoperatively, and was sustained. Definite or probable cognitive deficits were seen in 17.4% of patients and motor delays in 18.6%; both remained stable post-HT at 18.0% and 16.4%, respectively. Graft survival was worse in those with either pre- or post-HT deficits in functional status. Worse pre-HT functional status was associated with risk of graft failure (adjusted hazard ratio [aHR] per 10% decrease = 1.03 1.06 1.08, p < 0.001); worse 1-year post-HT functional status was much more strongly associated with risk of graft failure (aHR = 1.13 1.18 1.23, p < 0.001).

CONCLUSION

Pediatric HT recipients with decreased functional status are at higher risk for graft failure and mortality. These patients may benefit from early intervention aimed at improving functional status.

Generalizability of kidney transplant data in electronic health records - The Epic Cosmos database vs the Scientific Registry of Transplant Recipients

Developing real-world evidence from electronic health records (EHR) is vital to advancing kidney transplantation (KT). We assessed the feasibility of studying KT using the Epic Cosmos aggregated EHR data set, which includes 274 million unique individuals cared for in 238 US health systems, by comparing it with the Scientific Registry of Transplant Recipients (SRTR). We identified 69 418 KT recipients who underwent transplants between January 2014 and December 2022 in Cosmos (39.4% of all US KT transplants during this period). The demographics and clinical characteristics of recipients captured in Cosmos were consistent with the overall SRTR cohort. Survival estimates were generally comparable, although there were some differences in long-term survival. At 7 years posttransplant, patient survival was 80.4% in Cosmos and 77.8% in SRTR. Multivariable Cox regression showed consistent associations between clinical factors and mortality in both cohorts, with minor discrepancies in the associations between death and both age and race. In summary, Cosmos provides a reliable platform for KT research, allowing EHR-level clinical granularity not available with either the transplant registry or health care claims. Consequently, Cosmos will enable novel analyses to improve our understanding of KT management on a national scale.

Sex and Size Disparities in Access to Liver Transplant for Patients With Hepatocellular Carcinoma

Importance

Women on the liver transplant waiting list are less likely to undergo a transplant than men. Recent approaches to resolving this disparity have involved adjustments to Model for End-Stage Liver Disease (MELD) scoring, but this will not affect candidates who rely on exception scores rather than calculated MELD score, the majority of whom have hepatocellular carcinoma (HCC).

Objective

To evaluate the association between female sex, candidate size, and access to liver transplant among wait-listed patients with HCC.

Design, Setting, and Participants

This retrospective cohort study used US transplant registry data of all adult (aged ≥18 years) wait-listed liver transplant candidates receiving an HCC exception score between January 1, 2010, and March 2, 2023.

Exposure

Wait-listed liver transplant candidate sex.

Main Outcomes and Measures

The association of female sex with (1) deceased-donor liver transplant (DDLT) and (2) death or waiting list removal for health deterioration were estimated using multivariable competing-risks regression. Results with and without adjustment for candidate height and weight (mediators of the sex disparity) were compared.

Results

The cohort included 31 725 candidates with HCC (mean [SD] age at receipt of exception, 61.2 [7.1] years; 76.3% men). Compared with men, women had a lower 1-year cumulative incidence of DDLT (50.8% vs 54.0%; P < .001) and a higher 1-year cumulative incidence of death or delisting for health deterioration (16.2% vs 15.0%; P = .002). After adjustment, without accounting for size, women had a lower incidence of DDLT (subdistribution hazard ratio [SHR], 0.92; 95% CI, 0.89-0.95) and higher incidence of death or delisting (SHR, 1.06; 95% CI, 1.00-1.13) compared with men. When adjusting for candidate height and weight, there was no association of female sex with incidence of DDLT or death or delisting. However, at a height cutoff of 166 cm, short women compared with short men were still less likely to undergo a transplant (SHR, 0.93; 95% CI, 0.88-0.99).

Conclusions and Relevance

In this study, women with HCC were less likely to receive a DDLT and more likely to die while wait-listed than men with HCC; these differences were largely (but not entirely) explained by sex-based differences in candidate size. For candidates listed with exception scores, additional changes to allocation policy are needed to resolve the sex disparity, including solutions to improve access to size-matched donor livers for smaller candidates.

Variation Across Organ Procurement Organizations in Deceased-Donor Kidney Offer Notification Practices

INTRODUCTION

How offer notifications are distributed early in the kidney allocation timeline, including how widely they are offered, is unclear. A better understanding of offer notification practices across organ procurement organizations (OPOs) may identify opportunities for more efficient allocation.

METHODS

We merged the Scientific Registry of Transplant Recipients potential transplant recipient file with additional offer notification time stamps to identify 54 631 deceased-donor kidney match runs from 2017 to 2023. Offer notifications for a given match run are sent to candidates/centers in "batches." We quantified the number of offers in the initial batch-which theoretically reflects the OPO's initial estimate of how widely a kidney should be offered-and compared this metric across OPOs.

RESULTS

Kidneys were offered to a median of 14 candidates (IQR 9-38) in the first batch of notifications, and this varied across OPOs from 3 to 746 candidates per initial batch. Batch size at the OPO-level did not correlate with rank at kidney placement or OPO nonuse rate. OPOs in the highest quartile of batch size sent more offers (median 100) than presumably necessary to place kidneys (median rank at placement 21), and OPOs in the lowest quartile of batch size sent fewer offers (6) than needed to place kidneys (rank at placement 19).

CONCLUSIONS

Offer notification practices vary widely across OPOs, and many OPOs offer kidneys far more widely than necessary for placement. Optimization of offer notification practices may reduce unnecessary communications. Further research into allocation processes is needed to identify opportunities to improve efficiency of allocation for OPOs and transplant centers.

Safety of Kidney Transplantation from Donors with HIV

BACKGROUND

Kidney transplantation from donors with human immunodeficiency virus (HIV) to recipients with HIV is an emerging practice. It has been performed since 2016 under the U.S. congressional HIV Organ Policy Equity Act and is currently approved for research only. The Department of Health and Human Services is considering expanding the procedure to clinical practice, but data are limited to small case series that did not include donors without HIV as controls.

METHODS

In an observational study conducted at 26 U.S. centers, we compared transplantation of kidneys from deceased donors with HIV and donors without HIV to recipients with HIV. The primary outcome was a safety event (a composite of death from any cause, graft loss, serious adverse event, HIV breakthrough infection, persistent failure of HIV treatment, or opportunistic infection), assessed for noninferiority (margin for the upper bound of the 95% confidence interval, 3.00). Secondary outcomes included overall survival, survival without graft loss, rejection, infection, cancer, and HIV superinfection.

RESULTS

We enrolled 408 transplantation candidates, of whom 198 received a kidney from a deceased donor; 99 received a kidney from a donor with HIV and 99 from a donor without HIV. The adjusted hazard ratio for the composite primary outcome was 1.00 (95% confidence interval [CI], 0.73 to 1.38), which showed noninferiority. The following secondary outcomes were similar whether the donor had HIV or not: overall survival at 1 year (94% vs. 95%) and 3 years (85% vs. 87%), survival without graft loss at 1 year (93% vs. 90%) and 3 years (84% vs. 81%), and rejection at 1 year (13% vs. 21%) and 3 years (21% vs. 24%). The incidence of serious adverse events, infections, surgical or vascular complications, and cancer was similar in the groups. The incidence of HIV breakthrough infection was higher among recipients of kidneys from donors with HIV (incidence rate ratio, 3.14; 95%, CI, 1.02 to 9.63), with one potential HIV superinfection among the 58 recipients in this group with sequence data and no persistent failures of HIV treatment.

CONCLUSIONS

In this observational study of kidney transplantation in persons with HIV, transplantation from donors with HIV appeared to be noninferior to that from donors without HIV. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT03500315.).

Identifying predictors of resilience to stressors in single-arm studies of pre-post change

Many older adults experience a major stressor at some point in their lives. The ability to recover well after a major stressor is known as resilience. An important goal of geriatric research is to identify factors that influence resilience to stressors. Studies of resilience in older adults are typically conducted with a single-arm where everyone experiences the stressor. The simplistic approach of regressing change versus baseline yields biased estimates due to mathematical coupling and regression to the mean (RTM). We develop a method to correct the bias. We extend the method to include covariates. Our approach considers a counterfactual control group and involves sensitivity analyses to evaluate different settings of control group parameters. Only minimal distributional assumptions are required. Simulation studies demonstrate the validity of the method. We illustrate the method using a large, registry of older adults (N  =7239) who underwent total knee replacement (TKR). We demonstrate how external data can be utilized to constrain the sensitivity analysis. Naive analyses implicated several treatment effect modifiers including baseline function, age, body-mass index (BMI), gender, number of comorbidities, income, and race. Corrected analysis revealed that baseline (pre-stressor) function was not strongly linked to recovery after TKR and among the covariates, only age and number of comorbidities were consistently and negatively associated with post-stressor recovery in all functional domains. Correction of mathematical coupling and RTM is necessary for drawing valid inferences regarding the effect of covariates and baseline status on pre-post change. Our method provides a simple estimator to this end.

Interplay of Donor-Recipient Relationship and Donor Race in Living Liver Donation in the United States

INTRODUCTION

Living liver donation improves survival of end-stage liver disease (ESLD) patients. Yet, it continues to represent a small proportion of United States (U.S.) liver transplantation with existing racial disparities. We investigated the interplay of donor-recipient relationship and donor race to understand donor subgroups with no significant increase.

METHODS

We studied 4407 living liver donors in the U.S. from January 1, 2012, to December 31, 2022 (median age = 36 years, and 59% were biologically related to the recipient). We quantified the change in the number of donors per 3-year increment using negative binomial regression (incidence rate ratio [IRR]), stratified by donor-recipient relationship and race/ethnicity.

RESULTS

Among biologically related donors, the observed annual number of White donors increased from 146 to 253, Hispanic donors from 18 to 53, and Black donors decreased from 11 to 10. Among unrelated donors, White donors increased from 65 to 221, Hispanic donors from 4 to 25, and Black donors from 3 to 11. For the IRR of biologically related donors aged <40 and ≥40 years, White donors increased by 18% and 22%; Hispanic donors increased by 25% and 54%; and Black donors did not change. Likewise, the IRR of unrelated donors aged <40 and ≥40 years, White donors increased by 48% and 55%; Hispanic donors increased by 52% and 65%; and Black donors did not change.

CONCLUSIONS

While biologically related donors represent the majority of donors, unrelated donors have substantially risen in recent years, primarily driven by White donors. Although the rate of unrelated donations increased among Hispanic donors, the absolute number remains very small (≤25 donors/year). Interventions are needed to increase education among Hispanic and Black communities to grow unrelated living liver donations across race/ethnicity.

[The German Transplant Registry - An Analysis of Legacy Data 2006-2016]

INTRODUCTION

In 2018, medical transplant data from three institutions were merged to create a German transplant registry. Since June 2021, access to data of the registry has been available. It was planned to analyze the registry data in order to compare special allocation rules with regular allocation for heart, liver, lung, and kidney transplantation. Our approach led to a quality analysis of the registry.

METHODS

Upon request, legacy data (2006-2016) of the registry was provided, divided into 61 elements. From these elements, the user had to compile the required dataset. Data checks were performed for completeness, correct allocation of information, and consistency among different sources. Software used for these tasks included R, SQL, and Excel.

RESULTS

The initial elements ("waiting list" elements) of the four types of transplantations contained data from a total of 80,259 originally listed patients. However, these patients were only partially present in other elements resulting in complete datasets reflecting waiting time in only 23%, 30%, 50%, and 96%, and for post-transplantation outcomes in 14%, 11%, 38%, and 13% (heart, liver, lung, and kidney transplantation, respectively). The linking of urgency information with clinical data was successful in only a small proportion, with only 6% for heart transplantation. Incorrect and thus implausible allocations in the case of special allocation rules indicated incorrect entries in the registry. Data from different data providers were inconsistent.

DISCUSSION AND CONCLUSION

The incompleteness and incorrect data allocation raise doubts about the reliability of scientific studies based on the transplant registry. The complex structure also hinders the compilation of a reliable dataset, which is uncommon internationally. New data (acquisition since 2017) has only been available since December 2023. The transplant registry urgently needs restructuring. Competent clinical data management, involving transplant medical expertise, and continuous quality controls are essential in this process.

Center and Individual Willingness to Consider Heart and Lung Offers From Donors With Hepatitis C

INTRODUCTION

Transplants with hearts and lungs from donors with hepatitis C virus (HCV D+) have been proven safe and effective since development of direct-acting antivirals, yet the presence of HCV + persists as a reason to decline organs.

METHODS

We identified adult candidates listed January 1, 2015-March 8, 2023 for heart or lung transplant using the Scientific Registry of Transplant Recipients. We identified individual-level and center-level characteristics associated with listing to consider HCV D+ offers using multilevel logistic regression in a multivariable framework.

RESULTS

Over the study period, the annual percentage of candidates willing to consider HCV D+ offers increased for both heart (9.5%-74.3%) and lung (7.8%-59.5%), as did the percentage of centers listing candidates for HCV D+ heart (52.9%-91.1%) and lung (32.8%-82.8%) offers. Candidates at centers with more experience with HCV D+ transplants were more likely to consider HCV D+ organ offers. After adjustment, listing center explained 70% and 78% of the residual variance in willingness to consider HCV D+ hearts and lungs, respectively.

CONCLUSIONS

Although listing for consideration of HCV D+ offers has increased, it varies by transplant center. Center-level barriers to consideration of HCV D+ organs reduce recipients' transplant access.

Association of early steroid withdrawal with kidney transplant outcomes in first-transplant and retransplant recipients

BACKGROUND AND HYPOTHESIS

Early steroid withdrawal (ESW) is often preferred over conventional steroid maintenance (CSM) therapy for kidney transplant recipients with low immunological risks because it may minimize immunosuppression-related adverse events while achieving similar transplant outcomes. However, the risk-benefit balance of ESW could be less favorable in retransplant recipients given their unique immunological risk profile. We hypothesized that the association of ESW with transplant outcomes would differ between first-transplant and retransplant recipients.

METHODS

To assess whether the impact of ESW differs between first and retransplant recipients, we studied 210 086 adult deceased-donor kidney transplant recipients using the Scientific Registry of Transplant Recipients. Recipients who discontinued maintenance steroids before discharge from transplant admission were classified with ESW; all others were classified with CSM. We quantified the association of ESW (vs. CSM) with acute rejection, death-censored graft failure, and death, addressing retransplant as an effect modifier, using logistic/Cox regression with inverse probability weights to control for confounders.

RESULTS

In our cohort, 26 248 (12%) were retransplant recipients. ESW was used in 30% of first-transplant and 20% of retransplant recipients. Among first-transplant recipients, ESW was associated with no significant difference in acute rejection (aOR = 1.04 [95% CI = 1.00-1.09]), slightly higher hazard of graft failure (HR = 1.09 [95% CI = 1.05-1.12]), and slightly lower mortality (HR = 0.93 [95% CI = 0.91-0.95]) compared to CSM. Nonetheless, among retransplant recipients, ESW was associated with notably higher risk of acute rejection (OR = 1.42 [95% CI = 1.29-1.57]; interaction p < 0.001) and graft failure (HR = 1.24 [95% CI = 1.14-1.34]; interaction p = 0.003), and similar mortality (HR = 1.01 [95% CI = 0.94-1.08]; interaction p = 0.04).

CONCLUSIONS

In retransplant recipients, the negative impacts of ESW on transplant outcomes appear to be non-negligible. A more conservatively tailored approach to ESW might be necessary for retransplant recipients.

The Impact of HLA-DQαβ Heterodimer Mismatch on Living Donor Kidney Allograft Outcomes

BACKGROUND

HLA-DQ mismatch has been identified as a predictor of de novo donor-specific HLA antibody formation and antibody-mediated rejection. There are insufficient data to guide the incorporation of DQ mismatch into organ allocation decisions.

METHODS

We used a retrospective longitudinal cohort of adult living donor kidney transplant recipients from 11 centers across the United States for whom high-resolution class II typing was available. HLA-DQαβ heterodimer allele mismatch was quantified for all donor-recipient pairs, and outcome data were obtained through linkage with the Scientific Registry of Transplant Recipients.

RESULTS

We studied 3916 donor-recipient pairs. Recipient characteristics were notable for a median age of 51 (38-61) y, primarily unsensitized, with 74.5% of the cohort having 0% calculated panel-reactive antibody, and 60.4% with private insurance, for a median follow-up time of 5.86 y. We found that the HLA-DQαβ allele and HLA-DR antigen mismatch were each individually associated with an increased hazard of all-cause graft failure (adjusted hazard ratio [aHR] DQ = 1.03 1.14 1.28; aHR DR = 1.03 1.15 1.328), death-censored graft failure (aHR DQ =1.01 1.19 1.40; aHR DR = 0.099 1.18 1.39), and rejection. Having 2 HLA-DQαβ allele mismatches further increased the hazard of rejection even when controlling for HLA-DR mismatch (aHR 1.03 1.68 2.74).

CONCLUSIONS

HLA-DQαβ allele mismatch predicted allograft rejection even when controlling for HLA-DR antigen mismatch and were both independently associated with increased risk of graft failure or rejection in adult living kidney transplant recipients. Given the strong burden of disease arising from the HLA-DQ antibody formation, we suggest that HLA-DQαβ should be prioritized over HLA-DR in donor selection.

Seasonal Patterns of Living Kidney Donation in the United States From 1995 to 2019

BACKGROUND

The number of living kidney donors in the United States has declined since 2005, with variations based on the donor-recipient relationship. The reasons for this decline are unclear, and strategies to mitigate declined donations remain elusive. We examined the change in donor number monthly (within-year) versus annually (between-years) to inform potentially modifiable factors for future interventions.

METHODS

In this registry-based cohort analysis of 141 759 living kidney donors between 1995 and 2019, we used linear mixed-effects models for donor number per month and year to analyze between-year and within-year variation in donation. We used Poisson regression to quantify the change in the number of donors per season before and after 2005, stratified by donor-recipient relationship and zip-code household income tertile.

RESULTS

We observed a consistent summer surge in donations during June, July, and August. This surge was statistically significant for related donors (incidence rate ratio [IRR] range: 1.12-1.33) and unrelated donors (IRR range: 1.06-1.16) across donor income tertiles.

CONCLUSION

Our findings indicate lower rates of living kidney donation in non-summer months across income tertiles. Interventions are needed to address barriers to donation in non-summer seasons and facilitate donations throughout the year. Since the Organ Donor Leave Law provides a solid foundation for supporting year-round donation, extending the law's provisions beyond federal employees may mitigate identified seasonal barriers.

Waitlist Outcomes for Exception and Non-exception Liver Transplant Candidates in the United States Following Implementation of the Median MELD at Transplant (MMaT)/250-mile Policy

BACKGROUND

Since February 2020, exception points have been allocated equivalent to the median model for end-stage liver disease at transplant within 250 nautical miles of the transplant center (MMaT/250). We compared transplant rate and waitlist mortality for hepatocellular carcinoma (HCC) exception, non-HCC exception, and non-exception candidates to determine whether MMaT/250 advantages (or disadvantages) exception candidates.

METHODS

Using Scientific Registry of Transplant Recipients data, we identified 23 686 adult, first-time, active, deceased donor liver transplant (DDLT) candidates between February 4, 2020, and February 3, 2022. We compared DDLT rates using Cox regression, and waitlist mortality/dropout using competing risks regression in non-exception versus HCC versus non-HCC candidates.

RESULTS

Within 24 mo of study entry, 58.4% of non-exception candidates received DDLT, compared with 57.8% for HCC candidates and 70.5% for non-HCC candidates. After adjustment, HCC candidates had 27% lower DDLT rate (adjusted hazard ratio =  0.68 0.73 0.77 ) compared with non-exception candidates. However, waitlist mortality for HCC was comparable to non-exception candidates (adjusted subhazard ratio [asHR] =  0.93 1.03 1.15 ). Non-HCC candidates with pulmonary complications of cirrhosis or cholangiocarcinoma had substantially higher risk of waitlist mortality compared with non-exception candidates (asHR =  1.27 1.70 2.29 for pulmonary complications of cirrhosis, 1.35 2.04 3.07 for cholangiocarcinoma). The same was not true of non-HCC candidates with exceptions for other reasons (asHR =  0.54 0.88 1.44 ).

CONCLUSIONS

Under MMaT/250, HCC, and non-exception candidates have comparable risks of dying before receiving liver transplant, despite lower transplant rates for HCC. However, non-HCC candidates with pulmonary complications of cirrhosis or cholangiocarcinoma have substantially higher risk of dying before receiving liver transplant; these candidates may merit increased allocation priority.

Obesogenic Medication Use in End-Stage Kidney Disease and Association With Transplant Listing

OBJECTIVES

Obesogenic medications are a putative contributor to the obesity epidemic. While 20% of adults take ≥1 obesogenic medication, the proportion in the end-stage kidney disease (ESKD) population-a group enriched for cardiometabolic complications-is unknown. Obesogenic medications may contribute to obesity and hamper weight loss efforts to achieve transplant listing.

METHODS

Using 2017-2020 USRDS and Medicare claims, patients were identified as taking obesogenic medications if prescribed anticonvulsants, antidepressants, antidiabetics, anti-inflammatories, antipsychotics, and/or antihypertensives known to cause weight gain for ≥30 days in their first hemodialysis year. Ordinal logistic and Cox regression with inverse probability of treatment weighting were used to quantify obesogenic medications' association with body mass index (BMI) and listing, respectively.

RESULTS

Among 271 401 hemodialysis initiates, 63.5% took ≥1 obesogenic medication. For those in underweight, normal weight, overweight, and class I, II, and III categories, 54.3%, 58.4%, 63.1%, 66.5%, 68.6%, and 68.8% took ≥1, respectively. Number of obesogenic medications was associated with increased BMI; use of one was associated with 13% increased odds of higher BMI (aOR [adjusted odds ratio] 1.14; 95%CI: 1.13-1.16; p < 0.001), use of three was associated with a 55% increase (aOR 1.55; 95%CI: 1.53-1.57; p < 0.001). Any use was associated with 6% lower odds of transplant listing (aHR [adjusted hazard ratio] 0.94; 95%CI: 0.92-0.96; p < 0.001). Within each BMI category, obesogenic medication use was associated with lower listing likelihood.

CONCLUSIONS

Obesogenic medication use is common in ESKD patients-particularly those with obesity-and is associated with lower listing likelihood. Whenever possible, non-obesogenic alternatives should be chosen for ESKD patients attempting weight loss to achieve transplant listing.

Components of Residential Neighborhood Deprivation and Their Impact on the Likelihood of Live-Donor and Preemptive Kidney Transplantation

INTRODUCTION

Adults residing in deprived neighborhoods face various socioeconomic stressors, hindering their likelihood of receiving live-donor kidney transplantation (LDKT) and preemptive kidney transplantation (KT). We quantified the association between residential neighborhood deprivation index (NDI) and the likelihood of LDKT/preemptive KT, testing for a differential impact by race and ethnicity.

METHODS

We studied 403 937 adults (age ≥ 18) KT candidates (national transplant registry; 2006-2021). NDI and its 10 components were averaged at the ZIP-code level. Cause-specific hazards models were used to quantify the adjusted hazard ratio (aHR) of LDKT and preemptive KT across tertiles of NDI and its 10 components.

RESULTS

Candidates residing in high-deprivation neighborhoods were more likely to be female (40.1% vs. 36.2%) and Black (41.9% vs. 17.7%), and were less likely to receive both LDKT (aHR = 0.66, 95% confidence interval [CI]: 0.64-0.67) and preemptive KT (aHR = 0.60, 95% CI: 0.59-0.62) than those in low-deprivation neighborhoods. These associations differedby race and ethnicity (Black: aHRLDKT = 0.58, 95% CI: 0.55-0.62; aHRpreemptive KT = 0.68, 95% CI: 0.63-0.73; Pinteractions: LDKT < 0.001; Preemptive KT = 0.002). All deprivation components were associated with the likelihood of both LDKT and preemptive KT (except median home value): for example, higher median household income (LDKT: aHR = 1.08, 95% CI: 1.07-1.09; Preemptive KT: aHR = 1.10, 95% CI: 1.08-1.11) and educational attainments (≥high school [LDKT: aHR = 1.17, 95% CI: 1.15-1.18; Preemptive KT: aHR = 1.23, 95% CI: 1.21-1.25]).

CONCLUSION

Residence in socioeconomically deprived neighborhoods is associated with a lower likelihood of LDKT and preemptive KT, differentially impacting minority candidates. Identifying and understanding which neighborhood-level socioeconomic status contributes to these racial disparities can be instrumental in tailoring interventions to achieve health equity in LDKT and preemptive KT.

To decline or not to decline: Consequences of decision-making regarding lung offers from donors with hepatitis C

OBJECTIVE

Lung transplants from donors with hepatitis C (HCV D+) have excellent outcomes, but these organs continue to be declined. We evaluated whether (1) being listed to consider and (2) accepting versus declining HCV D+ offers provided a survival benefit to lung transplant candidates.

METHODS

Using the Scientific Registry of Transplant Recipients, we identified all adult (≥18 years) lung transplant candidates 2016-2021 and compared waitlist mortality between those willing versus not willing to consider HCV D+ offers using competing risk regression. We identified all candidates offered an HCV D+ lung that was later accepted and followed them from offer decision until death or end-of-study. We estimated adjusted mortality risk of accepting versus declining an HCV D+ lung offer using propensity-weighted Cox regression.

RESULTS

From 2016 to 2021, we identified 21,007 lung transplant candidates, 33.8% of whom were willing to consider HCV D+ offers. Candidates willing to consider HCV D+ offers had a 17% lower risk of waitlist mortality (subhazard ratio, 0.83; 95% confidence interval, 0.75-0.91, P < .001). Over the same period, 665 HCV D+ lung offers were accepted after being declined a total of 2562 times. HCV D+ offer acceptance versus decline was associated with a 20% lower risk of mortality (adjusted hazard ratio, 0.80; 95% confidence interval, 0.66-0.96, P = .02).

CONCLUSIONS

Considering HCV D+ lung offers was associated with a 17% lower risk of waitlist mortality, whereas accepting versus declining an HCV D+ lung offer was associated with a 20% lower risk of mortality. Centers and candidates should consider accepting suitable HCV D+ lung offers to optimize outcomes.

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.

National Incidence, Outcomes, and Management Strategies for Pre- and Post-Transplant Atrial Fibrillation in Heart Transplant Recipients

Background

Among heart transplant candidates, atrial fibrillation (AF) is a common comorbidity; however, little is known about the impact of pre-transplant AF on incidence of post-transplant AF or other transplant outcomes.

Methods

Adult heart transplant recipients transplanted from 07/01/2012 to 07/01/2021 with data available in both the Scientific Registry of Transplant Recipients and Symphony Health pharmacy databases were included. Recipients were categorized by presence of pre-transplant AF using prescription fill data. Perioperative outcomes and survival out to 5 years post-transplant were compared between those with and without pre-transplant AF.

Results

Of the 11,789 heart transplant recipients, 2,477 (21.0%) had pre-transplant AF. Pre-transplant AF was associated with an increased likelihood of pre-discharge stroke (aOR 2.13 [95%CI: 1.07-4.26], p=0.03) and dialysis (aOR 1.45 [1.05-2.00], p=0.02), as well as of post-transplant AF at 6 months (aOR 2.42 [1.44-1.48], p=0.001) and 1 year (aOR 2.81 [1.72-4.56], p<0.001). Pre-transplant AF was associated with increased post-transplant mortality at 30 days (aHR 2.39 [1.29-4.44], p=0.006) and 1 year (aHR 1.46 [95% CI: 1.01-2.13], p=0.04), but similar mortality at 5 years (aHR 1.23 [0.96-1.58], p=0.11).

Conclusion

Heart transplant recipients with pre-transplant AF had worse short-term outcomes and increased risk of developing post-transplant AF but comparable survival at 5 years post-transplant. Our findings emphasize the importance of increased monitoring for perioperative complications and highlight the long-term safety of heart transplantation in this population.

What Is New?

Patients with atrial fibrillation who undergo heart transplantation have worse short term survival (30-days and 1-year) but similar long term survival (5-years) compared to recipients without pre-transplant atrial fibrillation.Pre-transplant atrial fibrillation increases the risk of clinically significant post-transplant atrial fibrillation and peri-operative stroke.Rate vs rhythm control pharmacotherapy for atrial fibrillation is not associated with differences in survival in heart transplant recipients with pre-transplant atrial fibrillation.

What are the Clinical Implications?

Atrial fibrillation should not deter heart transplantation in appropriate candidates, though cardiovascular and stroke risk adjustment may be warranted.Use of amiodarone at doses ≤ 200 mg/day is not associated with reduced survival in heart transplant recipients with pre-transplant atrial fibrillation.

Design, cohort profile and comparison of the KTD-Innov study: a prospective multidimensional biomarker validation study in kidney allograft rejection

There is an unmet need for robust and clinically validated biomarkers of kidney allograft rejection. Here we present the KTD-Innov study (ClinicalTrials.gov, NCT03582436), an unselected deeply phenotyped cohort of kidney transplant recipients with a holistic approach to validate the clinical utility of precision diagnostic biomarkers. In 2018-2019, we prospectively enrolled consecutive adult patients who received a kidney allograft at seven French centers and followed them for a year. We performed multimodal phenotyping at follow-up visits, by collecting clinical, biological, immunological, and histological parameters, and analyzing a panel of 147 blood, urinary and kidney tissue biomarkers. The primary outcome was allograft rejection, assessed at each visit according to the international Banff 2019 classification. We evaluated the representativeness of participants by comparing them with patients from French, European, and American transplant programs transplanted during the same period. A total of 733 kidney transplant recipients (64.1% male and 35.9% female) were included during the study. The median follow-up after transplantation was 12.3 months (interquartile range, 11.9-13.1 months). The cumulative incidence of rejection was 9.7% at one year post-transplant. We developed a distributed and secured data repository in compliance with the general data protection regulation. We established a multimodal biomarker biobank of 16,736 samples, including 9331 blood, 4425 urinary and 2980 kidney tissue samples, managed and secured in a collaborative network involving 7 clinical centers, 4 analytical platforms and 2 industrial partners. Patients' characteristics, immune profiles and treatments closely resembled those of 41,238 French, European and American kidney transplant recipients. The KTD-Innov study is a unique holistic and multidimensional biomarker validation cohort of kidney transplant recipients representative of the real-world transplant population. Future findings from this cohort are likely to be robust and generalizable.

Neighborhood Segregation and Access to Live Donor Kidney Transplantation

Importance

Identifying the mechanisms of structural racism, such as racial and ethnic segregation, is a crucial first step in addressing the persistent disparities in access to live donor kidney transplantation (LDKT).

Objective

To assess whether segregation at the candidate's residential neighborhood and transplant center neighborhood is associated with access to LDKT.

Design, Setting, and Participants

In this cohort study spanning January 1995 to December 2021, participants included non-Hispanic Black or White adult candidates for first-time LDKT reported in the US national transplant registry. The median (IQR) follow-up time for each participant was 1.9 (0.6-3.0) years.

Main Outcome and Measures

Segregation, measured using the Theil H method to calculate segregation tertiles in zip code tabulation areas based on the American Community Survey 5-year estimates, reflects the heterogeneity in neighborhood racial and ethnic composition. To quantify the likelihood of LDKT by neighborhood segregation, cause-specific hazard models were adjusted for individual-level and neighborhood-level factors and included an interaction between segregation tertiles and race.

Results

Among 162 587 candidates for kidney transplant, the mean (SD) age was 51.6 (13.2) years, 65 141 (40.1%) were female, 80 023 (49.2%) were Black, and 82 564 (50.8%) were White. Among Black candidates, living in a high-segregation neighborhood was associated with 10% (adjusted hazard ratio [AHR], 0.90 [95% CI, 0.84-0.97]) lower access to LDKT relative to residence in low-segregation neighborhoods; no such association was observed among White candidates (P for interaction = .01). Both Black candidates (AHR, 0.94 [95% CI, 0.89-1.00]) and White candidates (AHR, 0.92 [95% CI, 0.88-0.97]) listed at transplant centers in high-segregation neighborhoods had lower access to LDKT relative to their counterparts listed at centers in low-segregation neighborhoods (P for interaction = .64). Within high-segregation transplant center neighborhoods, candidates listed at predominantly minority neighborhoods had 17% lower access to LDKT relative to candidates listed at predominantly White neighborhoods (AHR, 0.83 [95% CI, 0.75-0.92]). Black candidates residing in or listed at transplant centers in predominantly minority neighborhoods had significantly lower likelihood of LDKT relative to White candidates residing in or listed at transplant centers located in predominantly White neighborhoods (65% and 64%, respectively).

Conclusions

Segregated residential and transplant center neighborhoods likely serve as a mechanism of structural racism, contributing to persistent racial disparities in access to LDKT. To promote equitable access, studies should assess targeted interventions (eg, community outreach clinics) to improve support for potential candidates and donors and ultimately mitigate the effects of segregation.

A2/A2B to B deceased donor kidney transplantation in the Kidney Allocation System era

Kidney transplantation from blood type A2/A2B donors to type B recipients (A2→B) has increased dramatically under the current Kidney Allocation System (KAS). Among living donor transplant recipients, A2-incompatible transplants are associated with an increased risk of all-cause and death-censored graft failure. In light of this, we used data from the Scientific Registry of Transplant Recipients from December 2014 until June 2022 to evaluate the association between A2→B listing and time to deceased donor kidney transplantation (DDKT) and post-DDKT outcomes for A2→B recipients. Among 53 409 type B waitlist registrants, only 12.6% were listed as eligible to accept A2→B offers ("A2-eligible"). The rates of DDKT at 1-, 3-, and 5-years were 32.1%, 61.4%, and 72.1% among A2-eligible candidates and 14.1%, 29.9%, and 44.1% among A2-ineligible candidates, with the former experiencing a 133% higher rate of DDKT (Cox weighted hazard ratio (wHR) = 2.192.332.47; P < .001). The 7-year adjusted mortality was comparable between A2→B and B-ABOc (type B/O donors to B recipients) recipients (wHR 0.780.941.13, P = .5). Moreover, there was no difference between A2→B vs B-ABOc DDKT recipients with regards to death-censored graft failure (wHR 0.771.001.29, P > .9) or all-cause graft loss (wHR 0.820.961.12, P = .6). Following its broader adoption since the implementation of the kidney allocation system, A2→B DDKT appears to be a safe and effective transplant modality for eligible candidates. As such, A2→B listing for eligible type B candidates should be expanded.

Single center utilization and post-transplant outcomes of thoracoabdominal normothermic regional perfusion deceased cardiac donor organs

INTRODUCTION

Thoracoabdominal normothermic regional perfusion (TA-NRP) following cardiac death is an emerging multivisceral organ procurement technique. Recent national studies on outcomes of presumptive TA-NRP-procured organs are limited by potential misclassification since TA-NRP is not differentiated from donation after cardiac death (DCD) in registry data.

METHODS

We studied 22 donors whose designees consented to TA-NRP and organ procurement performed at our institution between January 20, 2020 and July 3, 2022. We identified these donors in SRTR to describe organ utilization and recipient outcomes and compared them to recipients of traditional DCD (tDCD) and donation after brain death (DBD) organs during the same timeframe.

RESULTS

All 22 donors progressed to cardiac arrest and underwent TA-NRP followed by heart, lung, kidney, and/or liver procurement. Median donor age was 41 years, 55% had anoxic brain injury, 45% were hypertensive, 0% were diabetic, and median kidney donor profile index was 40%. TA-NRP utilization was high across all organ types (88%-100%), with a higher percentage of kidneys procured via TA-NRP compared to tDCD (88% vs. 72%, p = .02). Recipient and graft survival ranged from 89% to 100% and were comparable to tDCD and DBD recipients (p ≥ .2). Delayed graft function was lower for kidneys procured from TA-NRP compared to tDCD donors (27% vs. 44%, p = .045).

CONCLUSION

Procurement from TA-NRP donors yielded high organ utilization, with outcomes comparable to tDCD and DBD recipients across organ types. Further large-scale study of TA-NRP donors, facilitated by its capture in the national registry, will be critical to fully understand its impact as an organ procurement technique.

Wait Time Advantage for Transplant Candidates With HIV Who Accept Kidneys From Donors With HIV Under the HOPE Act

BACKGROUND

Kidney transplant (KT) candidates with HIV face higher mortality on the waitlist compared with candidates without HIV. Because the HIV Organ Policy Equity (HOPE) Act has expanded the donor pool to allow donors with HIV (D + ), it is crucial to understand whether this has impacted transplant rates for this population.

METHODS

Using a linkage between the HOPE in Action trial (NCT03500315) and Scientific Registry of Transplant Recipients, we identified 324 candidates listed for D + kidneys (HOPE) compared with 46 025 candidates not listed for D + kidneys (non-HOPE) at the same centers between April 26, 2018, and May 24, 2022. We characterized KT rate, KT type (D + , false-positive [FP; donor with false-positive HIV testing], D - [donor without HIV], living donor [LD]) and quantified the association between HOPE enrollment and KT rate using multivariable Cox regression with center-level clustering; HOPE was a time-varying exposure.

RESULTS

HOPE candidates were more likely male individuals (79% versus 62%), Black (73% versus 35%), and publicly insured (71% versus 52%; P  < 0.001). Within 4.5 y, 70% of HOPE candidates received a KT (41% D + , 34% D - , 20% FP, 4% LD) versus 43% of non-HOPE candidates (74% D - , 26% LD). Conversely, 22% of HOPE candidates versus 39% of non-HOPE candidates died or were removed from the waitlist. Median KT wait time was 10.3 mo for HOPE versus 60.8 mo for non-HOPE candidates ( P  < 0.001). After adjustment, HOPE candidates had a 3.30-fold higher KT rate (adjusted hazard ratio = 3.30, 95% confidence interval, 2.14-5.10; P  < 0.001).

CONCLUSIONS

Listing for D + kidneys within HOPE trials was associated with a higher KT rate and shorter wait time, supporting the expansion of this practice for candidates with HIV.

Racial Disparities in Waiting List Outcomes of Patients Listed for Lung Transplantation

BACKGROUND

The Lung Allocation Score, implemented in 2005, prioritized lung transplant candidates by medical urgency rather than waiting list time and was expected to improve racial disparities in transplant allocation. We evaluated whether racial disparities in lung transplant persisted after 2005.

METHODS

We identified all wait-listed adult lung transplant candidates in the United States from 2005 through 2021 using the Scientific Registry of Transplant Recipients. We evaluated the association between race and receipt of a transplant by using a multivariable competing risk regression model adjusted for demographics, socioeconomic status, Lung Allocation Score, clinical measures, and time. We evaluated interactions between race and age, sex, socioeconomic status, and Lung Allocation Score.

RESULTS

We identified 33,158 candidates on the lung transplant waiting list between 2005 and 2021: 27,074 White (82%), 3350 African American (10%), and 2734 Hispanic (8%). White candidates were older, had higher education levels, and had lower Lung Allocation Scores (P < .001). After multivariable adjustment, African American and Hispanic candidates were less likely to receive lung transplants than White candidates (African American: adjusted subhazard ratio, 0.86; 95% CI, 0.82-0.91; Hispanic: adjusted subhazard ratio, 0.82; 95% CI, 0.78-0.87). Lung transplant was significantly less common among Hispanic candidates aged >65 years (P = .003) and non-White candidates from higher-poverty communities (African-American: P = .013; Hispanic: P =.0036).

CONCLUSIONS

Despite implementation of the Lung Allocation Score, racial disparities persisted for wait-listed African American and Hispanic lung transplant candidates and differed by age and poverty status. Targeted interventions are needed to ensure equitable access to this life-saving intervention.

Augmenting the Unites States transplant registry with external mortality data: A moving target ripe for further improvement

The Organ Procurement and Transplantation Network conducts a robust death verification process when augmenting the United States transplant registry with external sources of data. Process enhancements added over 35,000 externally verified deaths across waitlist candidates and transplant recipients for all organs beginning in April 2022. Ninety-four percent of added posttransplant deaths occurred beyond 5 years posttransplant, and over 74% occurred beyond 10 years. Deceased donor solid organ recipients transplanted from January 1, 2010, through October 31, 2020, were analyzed from January and July 2022 Organ Procurement and Transplantation Network Standard Transplant Analysis and Research and the Scientific Registry of Transplant Recipients Standard Analysis Files to quantify the impact of including vs excluding unverified deaths (not releasable to researchers) on posttransplant patient survival estimates. Across all organs, 1- and 5-year posttransplant survival rates were not substantially impacted; meaningful differences were observed in 10-year survival among kidney recipients. These findings bear important implications for anyone who utilized transplant registry data to examine long-term outcomes prior to the updated verification process. Users of transplant surveillance data should interpret results of long-term outcomes cautiously, particularly differences across subpopulations, and the transplant community should identify ways to improve data quality and minimize the reporting burden on transplant institutions.

Applying propensity methods to the United States transplant registry for external real-world evidence control arms for 5-year survival in the BENEFIT study

To address the challenges of assessing the impact of a reasonably likely surrogate endpoint on long-term graft survival in prospective kidney transplant clinical trials, the Transplant Therapeutics Consortium established a real-world evidence workgroup evaluating the scientific value of using transplant registry data as an external control to supplement the internal control group. The United Network for Organ Sharing retrospectively simulated the use of several distinct contemporaneous external control groups, applied multiple cause inference methods, and compared treatment effects to those observed in the BENEFIT study. Applying BENEFIT study enrollment criteria produced a smaller historical cyclosporine control arm (n = 153) and a larger, alternative (tacrolimus) historical control arm (n = 1069). Following covariate-balanced propensity scoring, Kaplan-Meier 5-year all-cause graft survivals were 81.3% and 81.7% in the Organ Procurement and Transplantation Network (OPTN) tacrolimus and cyclosporine external control arms, similar to 80.3% observed in the BENEFIT cyclosporine treatment arm. Five-year graft survival in the belatacept-less intensive arm was significantly higher than the OPTN controls using propensity scoring for comparing cyclosporine and tacrolimus. Propensity weighting using OPTN controls closely mirrored the BENEFIT study's long-term control (cyclosporine) arm's survival rate and the less intensive arm's treatment effect (significantly higher survival vs control). This study supports the feasibility and validity of using supplemental external registry controls for long-term survival in kidney transplant clinical trials.

Unrecognized opportunities: The landscape of pediatric kidney-paired donation in the United States

BACKGROUND

Pediatric (age < 18 years) kidney transplant (KT) candidates face increasingly complex choices. The 2014 kidney allocation system nearly doubled wait times for pediatric recipients. Given longer wait times and new ways to optimize compatibility, more pediatric candidates may consider kidney-paired donation (KPD). Motivated by this shift and the potential impact of innovations in KPD practice, we studied pediatric KPD procedures in the US from 2008 to 2021.

METHODS

We describe the characteristics and outcomes of pediatric KPD recipients with comparison to pediatric non-KPD living donor kidney transplants (LDKT), pediatric LDKT recipients, and pediatric deceased donor (DDKT) recipients.

RESULTS

Our study cohort includes 4987 pediatric DDKTs, 3447 pediatric non-KPD LDKTs, and 258 pediatric KPD transplants. Fewer centers conducted at least one pediatric KPD procedure compared to those that conducted at least one pediatric LDKT or DDKT procedure (67, 136, and 155 centers, respectively). Five centers performed 31% of the pediatric KPD transplants. After adjustment, there were no differences in graft failure or mortality comparing KPD recipients to non-KPD LDKT, LDKT, or DDKT recipients.

DISCUSSION

We did not observe differences in transplant outcomes comparing pediatric KPD recipients to controls. Considering these results, KPD may be underutilized for pediatric recipients. Pediatric KT centers should consider including KPD in KT candidate education. Further research will be necessary to develop tools that could aid clinicians and families considering the time horizon for future KT procedures, candidate disease and histocompatibility characteristics, and other factors including logistics and donor protections.

Uptake and 1-year outcomes of lung transplantation for COVID-19

OBJECTIVE

End-stage lung disease from severe COVID-19 infection is an increasingly common indication for lung transplantation (LT), but there are limited data on outcomes. We evaluated 1-year COVID-19 LT outcomes.

METHODS

We identified all adult US LT recipients January 2020 to October 2022 in the Scientific Registry for Transplant Recipients, using diagnosis codes to identify recipients transplanted for COVID-19. We used multivariable regression to compare in-hospital acute rejection, prolonged ventilator support, tracheostomy, dialysis, and 1-year mortality between COVID-19 and non-COVID-19 recipients, adjusting for donor, recipient, and transplant characteristics.

RESULTS

LT for COVID-19 increased from 0.8% to 10.7% of total LT volume during 2020 to 2021. The number of centers performing LT for COVID-19 increased from 12 to 50. Recipients transplanted for COVID-19 were younger; were more likely to be male and Hispanic; were more likely to be on a ventilator, extracorporeal membrane oxygenation support, and dialysis pre-LT; were more likely to receive bilateral LT; and had higher lung allocation score and shorter waitlist time than other recipients (all P values < .001). COVID-19 LT had higher risk of prolonged ventilator support (adjusted odds ratio, 2.28; P < .001), tracheostomy (adjusted odds ratio 5.3; P < .001), and longer length of stay (median, 27 vs 19 days; P < .001). Risk of in-hospital acute rejection (adjusted odds ratio, 0.99; P = .95) and 1-year mortality (adjusted hazard ratio, 0.73; P = .12) were similar for COVID-19 LTs and LTs for other indications, even accounting for center-level differences.

CONCLUSIONS

COVID-19 LT is associated with higher risk of immediate postoperative complications but similar risk of 1-year mortality despite more severe pre-LT illness. These encouraging results support the ongoing use of LT for COVID-19-related lung disease.

Multi-Task Learning for Post-transplant Cause of Death Analysis: A Case Study on Liver Transplant

Organ transplant is the essential treatment method for some end-stage diseases, such as liver failure. Analyzing the post-transplant cause of death (CoD) after organ transplant provides a powerful tool for clinical decision making, including personalized treatment and organ allocation. However, traditional methods like Model for End-stage Liver Disease (MELD) score and conventional machine learning (ML) methods are limited in CoD analysis due to two major data and model-related challenges. To address this, we propose a novel framework called CoD-MTL leveraging multi-task learning to model the semantic relationships between various CoD prediction tasks jointly. Specifically, we develop a novel tree distillation strategy for multi-task learning, which combines the strength of both the tree model and multi-task learning. Experimental results are presented to show the precise and reliable CoD predictions of our framework. A case study is conducted to demonstrate the clinical importance of our method in the liver transplant.

COVID-19 and Access to Kidney Transplantation for Older Candidates in the United States: A National Registry Study

Rationale & Objective

Coronavirus disease (COVID)-19 has likely impacted accessibility to transplantation services among older adults (age ≥65 years). We quantified the impact of COVID-19 on kidney transplantation access for older kidney-only candidates registered on the United States (US) kidney waitlist.

Study Design

Retrospective analysis of registry data.

Setting & Participants

57,222 older adults who were part of or added to the US kidney waitlist between January 1, 2016 and February 28, 2022, identified using the Scientific Registry of Transplant Recipients (SRTR).

Exposures

Four COVID-19 waves and one nonwave period based on the national incidence of COVID-19 in the US (initial: March 15-May 30, 2020; winter 2020-2021: December 1, 2020-January 31, 2021; delta: August 1, 2021-September 30, 2021; omicron: December 1, 2021-February 28, 2022; nonwave: inter-wave periods).

Outcomes

Waitlist registrations, deceased-donor kidney transplants, living-donor kidney transplants, waitlist mortality, and waitlist removals due to deteriorating condition (hereafter referred to as removals).

Analytical Approach

Poisson regression for the adjusted incidence rate ratio (aIRR) of each outcome during the COVID-19 waves and the nonwave period relative to reference (January 1, 2016-December 31, 2019), adjusted for seasonality and secular trends.

Results

Waitlist registrations initially declined and increased henceforth. Deceased-donor kidney transplants and living-donor kidney transplants remained below-expected levels during all waves. Waitlist mortality peaked during the winter 2020-2021 wave (aIRR: 1.701.982.30) and has declined since; mortality rates were 139%, 107%, and 251% above expected for Black candidates, men, and candidates aged ≥75 years, respectively, during the winter 2020-2021 wave. Removals increased from 22% below expected levels (initial wave) to 26% above expected levels (omicron wave); removals were nonsignificantly higher than expected during the omicron wave for older Black and Hispanic candidates.

Limitations

The findings are not generalizable to those listed at earlier ages with prolonged waitlist times. Additionally, using national COVID-19 incidence does not consider local policy and health care variations. Lastly, aIRRs must be interpreted cautiously due to smaller daily event counts.

Conclusions

COVID-19 was associated with fewer transplants and increased mortality and removals in older kidney transplant candidates. Transplant providers should consider this impact and implement policies and practices to ensure the continuity of care.

Plain-Language Summary

The proportion of older adults on the kidney transplant waitlist is increasing, but the impact of COVID-19 on this population is not well characterized. In this study, we looked at incident waitlist registrations, deceased- and living-donor kidney transplants, and waitlist mortality and removals due to deteriorating condition over 4 waves of COVID-19. We found that transplantation services did not fully recover to prepandemic levels as of March 2022. Notably, racial/ethnic minorities and older men experienced lower rates of kidney transplants and higher rates of waitlist mortality, respectively, relative to White candidates and older women. Identifying vulnerable subpopulations affected by COVID-19 and its long-term impact is crucial for creating strategies to ensure the continuity of care in this population during public health emergencies.

Sex-based Disparities in Access to Liver Transplantation for Waitlisted Patients With Model for End-stage Liver Disease Score of 40

OBJECTIVE

To determine the association of sex with access to liver transplantation among candidates with the highest possible model for end-stage liver disease score (MELD 40).

BACKGROUND

Women with end-stage liver disease are less likely than men to receive liver transplantation due in part to MELD's underestimation of renal dysfunction in women. The extent of the sex-based disparity among patients with high disease severity and equally high MELD scores is unclear.

METHODS

Using national transplant registry data, we compared liver offer acceptance (offers received at match MELD 40) and waitlist outcomes (transplant vs death/delisting) by sex for 7654 waitlisted liver transplant candidates from 2009 to 2019 who reached MELD 40. Multivariable logistic and competing-risks regression was used to estimate the association of sex with the outcome and adjust for the candidate and donor factors.

RESULTS

Women (N = 3019, 39.4%) spent equal time active at MELD 40 (median: 5 vs 5 days, P = 0.28) but had lower offer acceptance (9.2% vs 11.0%, P < 0.01) compared with men (N = 4635, 60.6%). Adjusting for candidate/donor factors, offers to women were less likely accepted (odds ratio = 0.87, P < 0.01). Adjusting for candidate factors, once they reached MELD 40, women were less likely to be transplanted (subdistribution hazard ratio = 0.90, P < 0.01) and more likely to die or be delisted (subdistribution hazard ratio = 1.14, P = 0.02).

CONCLUSIONS

Even among candidates with high disease severity and equally high MELD scores, women have reduced access to liver transplantation and worse outcomes compared with men. Policies addressing this disparity should consider factors beyond MELD score adjustments alone.

Evaluating Cost-Effectiveness in Using High-Kidney Donor Profile Index Organs

A more granular donor kidney grading scale, the kidney donor profile index (KDPI), has recently emerged in contradistinction to the standard criteria donor/expanded criteria donor framework. In this paper, we built a Markov decision process model to evaluate the survival, quality-adjusted life years (QALY), and cost advantages of using high-KDPI kidneys based on multiple KDPI strata over a 60-month time horizon as opposed to remaining on the waiting list waiting for a lower-KDPI kidney. Data for the model were gathered from the Scientific Registry of Transplant Recipients and the United States Renal Data System Medicare parts A, B, and D databases. Of the 129,024 phenotypes delineated in this model, 65% of them would experience a survival benefit, 81% would experience an increase in QALYs, 87% would see cost-savings, and 76% would experience cost-savings per QALY from accepting a high-KDPI kidney rather than remaining on the waiting list waiting for a kidney of lower-KDPI. Classification and regression tree analysis (CART) revealed the main drivers of increased survival in accepting high-KDPI kidneys were wait time ≥30 months, panel reactive antibody (PRA) <90, age ≥45 to 65, diagnosis leading to renal failure, and prior transplantation. The CART analysis showed the main drivers of increased QALYs in accepting high-kidneys were wait time ≥30 months, PRA <90, and age ≥55 to 65.

Thoracic retransplantation: Does time to retransplantation matter?

OBJECTIVE

For some individuals, chronic allograft failure is best treated with retransplantation. We sought to determine if time to retransplantation impacts short- and long-term outcomes for heart or lung retransplant recipients with a time to retransplantation more than 1 year.

METHODS

The United Network for Organ Sharing/Organ Procurement and Transplantation Network STAR file was queried for all adult, first-time heart (June 1, 2006, to September 30, 2020) and lung (May 1, 2005, to September 30, 2020) retransplantations with a time to retransplantation of at least 1 year. Patients were grouped according to the tertile of time to retransplantation (tertile 1: 1-7.7 years, tertile 2: 7.7-14.7 years, tertile 3: 14.7+ years; lung: tertile 1: 1-2.8 years, tertile 2: 2.8-5.6 years, tertile 3: 5.6+ years). The primary outcome was survival after retransplantation. Comparative statistics identified differences in groups, and Kaplan-Meier methods and a Cox proportional hazard model were used for survival analysis.

RESULTS

After selection, 908 heart and 871 lung retransplants were identified. Among heart retransplant recipients, tertile 1 was associated with male sex, smoking history, higher listing status, and increased mechanical support pretransplant. Tertile 3 had the highest rate of concomitant kidney transplant; however, the incidence of morbidity and in-hospital mortality was similar among the groups. Unadjusted and adjusted analyses revealed no survival difference among all groups. Regarding lung retransplant recipients, tertile 1 was associated with increased lung allocation score, pretransplant hospitalization, and mechanical support. Unadjusted and adjusted survival analyses revealed decreased survival in tertile 1.

CONCLUSIONS

Time to retransplant does not appear to affect heart recipients with a time to retransplantation of more than 1 year; however, shorter time to retransplantation for prior lung recipients is associated with decreased survival. Potential lung retransplant candidates with a time to retransplantation of less than 2.8 years should be carefully evaluated before retransplantation.

The causes of death in patients with nonalcoholic steatohepatitis following liver transplantation stratified using pre-liver transplant BMI

BACKGROUND & AIMS

Determining the effects of pre-liver transplant (LT) BMI independent of underlying ascites on the post-LT outcomes of patients with nonalcoholic steatohepatitis (NASH) is needed to clarify the paradoxical and protective effects of obesity on post-LT endpoints. In order to accomplish this, we used graded severities of ascites to stratify the NASH-LT population and to perform an ascites-specific strata analysis with differing pre-LT BMI levels.

METHODS

2005-2019 United Network for Organ Sharing (UNOS) Standard Transplant Analysis and Research (STAR) database was queried to select patients with NASH, who were categorized into specific sets of ascites severity: no ascites (n = 1188), mild ascites (n = 4463), and moderate ascites (n = 3525). Then, BMI classification (underweight: < 18.5, normal: 18.5-25, overweight: 25-30, obese: ≥ 30 kg/m2) was used to stratify each ascites-specific group and to compare to the post-LT mortality endpoints. Those under 18 years old and those who received living/multi-organ transplants were excluded.

RESULTS

Among each ascites category, there were the following numbers of normal, underweight, overweight, and obese BMI patients respectively; no ascites: 161, 4, 359, 664; mild ascites: 643, 28, 1311, 2481; and moderate ascites: 529, 25, 1030, 1941. The obese BMI cohort was at a lower risk of all-cause mortality compared to recipients with normal BMI with mild ascites (aHR: 0.79, 95% Confidence Interval (CI) 0.65-0.94, p-value = 0.010; case-incidence 47.10 vs 56.81 deaths per 1000 person-years) and moderate ascites (aHR: 0.77, 95% CI 0.63-0.94, p-value = 0.009; case-incidence 53.71 vs 66.17 deaths per 1000 person-years). In addition, the overweight BMI cohort with mild ascites demonstrated a lower hazard of all-cause mortality (aHR: 0.80, 95% CI 0.66-0.97, p-value = 0.03; case-incidence 49.09 vs 56.81 deaths per 1000 person-years). There was no difference in graft failure for the three BMI groups (underweight, overweight, and obese) in comparison to normal BMI. Furthermore, the overweight BMI group with mild ascites cohort demonstrated a lower hazard of death due to general infectious causes (aHR: 0.51, 95% CI 0.32-0.83, p = 0.006; case-incidence 6.12 vs 11.91 deaths per 1000 person-years) and sepsis (aHR: 0.49, 95% CI 0.27-0.86, p = 0.01; case-incidence 4.31 vs 8.50 deaths per 1000 person-years).

CONCLUSION

The paradoxical effects of obesity in reducing the risks of all-cause death appears to be in part modulated by ascites. The current study emphasizes the need to evaluate BMI with concomitant ascites severity pre-LT to accurately prognosticate post-LT outcomes when evaluating NASH patients with advanced liver disease.

Transplant Candidate Outcomes After Declining a DCD Liver in the United States

BACKGROUND

In the context of the organ shortage, donation after circulatory death (DCD) provides an opportunity to expand the donor pool. Although deceased-donor liver transplantation from DCD donors has expanded, DCD livers continue to be discarded at elevated rates; the use of DCD livers from older donors, or donors with comorbidities, is controversial.

METHODS

Using US registry data from 2009 to 2020, we identified 1564 candidates on whose behalf a DCD liver offer was accepted ("acceptors") and 16 981 candidates on whose behalf the same DCD offers were declined ("decliners"). We characterized outcomes of decliners using a competing risk framework and estimated the survival benefit (adjusted hazard ratio [95% confidence interval]) of accepting DCD livers using Cox regression.

RESULTS

Within 10 y of DCD offer decline, 50.9% of candidates died or were removed from the waitlist before transplantation with any type of allograft. DCD acceptors had lower mortality compared with decliners at 10 y postoffer (35.4% versus 48.9%, P < 0.001). After adjustment for candidate covariates, DCD offer acceptance was associated with a 46% reduction in mortality (0.54 [0.49-0.61]). Acceptors of older (age ≥50), obese (body mass index ≥30), hypertensive, nonlocal, diabetic, and increased risk DCD livers had 44% (0.56 [0.42-0.73]), 40% (0.60 [0.49-0.74]), 48% (0.52 [0.41-0.66]), 46% (0.54 [0.45-0.65]), 32% (0.68 [0.43-1.05]), and 45% (0.55 [0.42-0.72]) lower mortality risk compared with DCD decliners, respectively.

CONCLUSIONS

DCD offer acceptance is associated with considerable long-term survival benefits for liver transplant candidates, even with older DCD donors or donors with comorbidities. Increased recovery and utilization of DCD livers should be encouraged.

Characterizing the risk of human leukocyte antigen-incompatible living donor kidney transplantation in older recipients

Older compatible living donor kidney transplant (CLDKT) recipients have higher mortality and death-censored graft failure (DCGF) compared to younger recipients. These risks may be amplified in older incompatible living donor kidney transplant (ILDKT) recipients who undergo desensitization and intense immunosuppression. In a 25-center cohort of ILDKT recipients transplanted between September 24, 1997, and December 15, 2016, we compared mortality, DCGF, delayed graft function (DGF), acute rejection (AR), and length of stay (LOS) between 234 older (age ≥60 years) and 1172 younger (age 18-59 years) recipients. To investigate whether the impact of age was different for ILDKT recipients compared to 17 542 CLDKT recipients, we used an interaction term to determine whether the relationship between posttransplant outcomes and transplant type (ILDKT vs CLDKT) was modified by age. Overall, older recipients had higher mortality (hazard ratio: 1.632.072.65, P < .001), lower DCGF (hazard ratio: 0.360.530.77, P = .001), and AR (odds ratio: 0.390.540.74, P < .001), and similar DGF (odds ratio: 0.461.032.33, P = .9) and LOS (incidence rate ratio: 0.880.981.10, P = 0.8) compared to younger recipients. The impact of age on mortality (interaction P = .052), DCGF (interaction P = .7), AR interaction P = .2), DGF (interaction P = .9), and LOS (interaction P = .5) were similar in ILDKT and CLDKT recipients. Age alone should not preclude eligibility for ILDKT.