Understanding Delayed Graft Function to Improve Organ Utilization and Patient Outcomes: Report of a Scientific Workshop Sponsored by the National Kidney Foundation

Delayed graft function (DGF) is a common complication after kidney transplant. Despite extensive literature on the topic, the extant definition of DGF has not been conducive to advancing the scientific understanding of the influences and mechanisms contributing to its onset, duration, resolution, or long-term prognostic implications. In 2022, the National Kidney Foundation sponsored a multidisciplinary scientific workshop to comprehensively review the current state of knowledge about the diagnosis, therapy, and management of DGF and conducted a survey of relevant stakeholders on topics of clinical and regulatory interest. In this Special Report, we propose and defend a novel taxonomy for the clinical and research definitions of DGF, address key regulatory and clinical practice issues surrounding DGF, review the current state of therapies to reduce and/or attenuate DGF, offer considerations for clinical practice related to the outpatient management of DGF, and outline a prospective research and policy agenda.

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.

Psychosocial characteristics of potential and actual living kidney donors

The psychosocial assessment is an essential component of the living kidney donor (LKD) evaluation. However, it remains uncertain how specific psychosocial factors impact LKD eligibility. We performed a retrospective chart review of LKD candidates who initiated the evaluation process and who had completed a required, in-person licensed social work (LSW) visit. LSW notes were reviewed for frequency of psychosocial factors that may impact the success of LKD candidate approval by the selection committee. 325 LKD candidates were included in the study: 104 not-approved and 221 approved. Not-approved LKD candidates were more likely to receive a negative family reaction to wanting to donate than approved LKD candidates (8.7% vs 1.4%, p < 0.01). On multivariate analysis, Black race, history of psychiatric illness, highest level of education being high school, and high psychosocial risk score assignment were all associated with a lower odds ratio of being approved. The majority of not-approved LKD candidates were disqualified for medical reasons (N = 76, 73.1%). In conclusion, psychosocial factors impact donation even after LKD candidates make it to an in-person evaluation.

Patient years lost due to cytomegalovirus serostatus mismatching in the scientific registry of transplant recipients

Background

The cytomegalovirus (CMV) mismatch rate in deceased donor kidney transplant (DDKT) recipients in the US remains above 40%. Since CMV mismatching is common in DDKT recipients, the cumulative effects may be significant in the context of overall patient and graft survival. Our primary objective was to describe the short- and long-term risks associated with high-risk CMV donor positive/recipient negative (D+/R-) mismatching among DDKT recipients with the explicit goal of deriving a mathematical mismatching penalty.

Methods

We conducted a retrospective, secondary analysis of the Scientific Registry of Transplant Recipients (SRTR) database using donor-matched DDKT recipient pairs (N=105,608) transplanted between 2011-2022. All-cause mortality and graft failure hazard ratios were calculated from one year to ten years post-DDKT. All-cause graft failure included death events. Survival curves were calculated using the Kaplan-Meier estimation at 10 years post-DDKT and extrapolated to 20 years to provide the average graft days lost (aGDL) and average patient days lost (aPDL) due to CMV D+/R- serostatus mismatching. We also performed an age-based stratification analysis to compare the relative risk of CMV D+ mismatching by age.

Results

Among 31,518 CMV D+/R- recipients, at 1 year post-DDKT, the relative risk of death increased by 29% (p<0.001), and graft failure increased by 17% (p<0.001) as compared to matched CMV D+/R+ group (N=31,518). Age stratification demonstrated a significant increase in the risk associated with CMV mismatching in patients 40 years of age and greater. The aGDL per patient due to mismatching was 125 days and the aPDL per patient was 100 days.

Conclusion

The risks of CMV D+/R- mismatching are seen both at 1 year post-DDKT period and accumulated throughout the lifespan of the patient, with the average CMV D+/R- recipient losing more than three months of post-DDKT survival time. CMV D+/R- mismatching poses a more significant risk and a greater health burden than previously reported, thus obviating the need for better preventive strategies including CMV serodirected organ allocation to prolong lifespans and graft survival in high-risk patients.

30- and 60-Day Readmission Rates for Children With Heart Failure in the United States

BACKGROUND

Studies on readmission for pediatric heart failure (HF) patients is sparse.

OBJECTIVES

This study evaluated 30- and 60-day readmission rates in pediatric HF patients from 2010 to 2019.

METHODS

The authors used data from the Nationwide Readmission Database to evaluate trends in 30- and 60-day hospital readmissions among pediatric patients with HF and compare them with adults with HF. Readmissions were also stratified by sex, diagnosis, neighborhood income, and hospital volume.

RESULTS

There were 84,731 hospital admissions for HF. Compared with children without HF, those with HF were older, had Medicare/Medicaid insurance, and resided in micropolitan areas and low-income neighborhoods. The 30- (19.5% vs 3.1%) and 60-day (27.5% vs 4.3%) all-cause readmission rates were higher for children with HF compared with those without HF. Compared with children without HF, lengths of stay, deaths, and costs related to their readmission were higher for children readmitted with HF (P < 0.05 for all). There was no significant decline in pediatric HF-related 30- or 60- day readmissions during the study period overall, or for those with congenital heart disease (P > 0.05), unlike adult HF readmissions (P < 0.01). Infants were at highest risk, and readmission rates for teenagers are rising.

CONCLUSIONS

The 30- and 60-day readmission rates for pediatric patients with HF in the current era is high (∼20% and 30%, respectively). Unlike adult HF, pediatric HF readmission rates have not declined. Pediatric HF patients readmitted to the hospital have higher death rates and greater resource utilization than patients without HF. National measures to decrease readmissions for pediatric patients with HF is warranted.

Performance of estimated glomerular filtration rate equations in Black living kidney donor candidates

INTRODUCTION

New estimated glomerular filtration rate (eGFR) equations using serum creatinine and/or cystatin C have been derived to eliminate adjustment by perceived Black ancestry. We sought to analyze the performance of newer eGFR equations among Black living kidney donor candidates.

METHODS

Black candidates (n = 64) who had measured iothalamate GFR between January 2015 and October 2021 were included, and eGFR was calculated using race adjusted (eGFRcr2009 and eGFRcr-cys2012) and race unadjusted (eGFRcys2012, eGFRcr2021, and eGFRcr-cys2021) CKD-EPI equations. Bias and accuracy were calculated.

RESULTS

The eGFRcr2021 equation had a negative bias of 9 mL/min/1.73 m2 , while other equations showed a modest positive bias. Accuracy within 10% and 30% was greatest using the eGFRcr-cys2021 equation. With the eGFRcr2021 equation, 9.4% of donors with an mGFR > 80 mL/min/1.73 m2 were misclassified as having an eGFR < 80 mL/min/1.73 m2 . eGFR was also compared among 18 kidney donors at 6-24 months post-donation. Post-donation, the percentage of donors with an eGFR < 60 mL/min/1.73 m2 was 44% using the eGFRcr2021 equation compared to 11% using the eGFRcr-cys2021 equation.

CONCLUSION

The CKD-EPICr2021 equation appears to underestimate true GFR in Black living donor candidates. Alternatively, compared to CKD-EPICr2021, the CKD-EPICr-CysC2021 equation appears to perform with less bias and improved accuracy.

UNOS Decisions Impact Data Integrity of the OPTN Data Registry

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Discrepant Outcomes between National Kidney Transplant Data Registries in the United States

SIGNIFICANCE STATEMENT

Effects of reduced access to external data by transplant registries to improve accuracy and completeness of the collected data are compounded by different data management processes at three US organizations that maintain kidney transplant-related datasets. This analysis suggests that the datasets have large differences in reported outcomes that vary across different subsets of patients. These differences, along with recent disclosure of previously missing outcomes data, raise important questions about completeness of the outcome measures. Differences in recorded deaths seem to be increasing in recent years, reflecting the adverse effects of restricted access to external data sources. Although these registries are invaluable sources for the transplant community, discrepancies and incomplete reporting risk undermining their value for future analyses, particularly when used for developing national transplant policy or regulatory measures.

BACKGROUND

Central to a transplant registry's quality are accuracy and completeness of the clinical information being captured, especially for important outcomes, such as graft failure or death. Effects of more limited access to external sources of death data for transplant registries are compounded by different data management processes at the United Network for Organ Sharing (UNOS), the Scientific Registry of Transplant Recipients (SRTR), and the United States Renal Data System (USRDS).

METHODS

This cross-sectional registry study examined differences in reported deaths among kidney transplant candidates and recipients of kidneys from deceased and living donors in 2000 through 2019 in three transplant datasets on the basis of data current as of 2020. We assessed annual death rates and survival estimates to visualize trends in reported deaths between sources.

RESULTS

The UNOS dataset included 77,605 deaths among 315,346 recipients and 61,249 deaths among 275,000 nonpreemptively waitlisted candidates who were never transplanted. The SRTR dataset included 87,149 deaths among 315,152 recipients and 60,042 deaths among 259,584 waitlisted candidates. The USRDS dataset included 89,515 deaths among 311,955 candidates and 63,577 deaths among 238,167 waitlisted candidates. Annual death rates among the prevalent transplant population show accumulating differences across datasets-2.31%, 4.00%, and 4.03% by 2019 from UNOS, SRTR, and USRDS, respectively. Long-term survival outcomes were similar among nonpreemptively waitlisted candidates but showed more than 10% discordance between USRDS and UNOS among transplanted patients.

CONCLUSIONS

Large differences in reported patient outcomes across datasets seem to be increasing, raising questions about their completeness. Understanding the differences between these datasets is essential for accurate, reliable interpretation of analyses that use these data for policy development, regulatory oversight, and research.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/JASN/2023_10_24_JASN0000000000000194.mp3.

Disparities in Kidney Transplant Waitlisting Among Young Patients Without Medical Comorbidities

Importance

Disparities in kidney transplant referral and waitlisting contribute to disparities in kidney disease outcomes. Whether these differences are rooted in population differences in comorbidity burden is unclear.

Objective

To examine whether disparities in kidney transplant waitlisting were present among a young, relatively healthy cohort of patients unlikely to have medical contraindications to kidney transplant.

Design, Setting, and Participants

This retrospective cohort study used the US Renal Data System Registry to identify patients with end-stage kidney disease who initiated dialysis between January 1, 2005, and December 31, 2019. Patients who were older than 40 years, received a preemptive transplant, were preemptively waitlisted, or had documented medical comorbidities other than hypertension or smoking were excluded, yielding an analytic cohort of 52 902 patients. Data were analyzed between March 1, 2022, and February 1, 2023.

Main Outcome(s) and Measure(s)

Kidney transplant waitlisting after dialysis initiation.

Results

Of 52 902 patients (mean [SD] age, 31 [5] years; 31 132 [59%] male; 3547 [7%] Asian/Pacific Islander, 20 782 [39%] Black/African American, and 28 006 [53%] White) included in the analysis, 15 840 (30%) were waitlisted for a kidney transplant within 1 year of dialysis initiation, 11 122 (21%) were waitlisted between 1 and 5 years after dialysis initiation, and 25 940 (49%) were not waitlisted by 5 years. Patients waitlisted within 1 year of dialysis initiation were more likely to be male, to be White, to be employed full time, and to have had predialysis nephrology care. There were large state-level differences in the proportion of patients waitlisted within 1 year (median, 33%; range, 15%-58%). In competing risk regression, female sex (adjusted subhazard ratio [SHR], 0.92; 95% CI, 0.90-0.94), Hispanic ethnicity (SHR, 0.77; 95% CI, 0.75-0.80), and Black race (SHR, 0.66; 95% CI, 0.64-0.68) were all associated with lower waitlisting after dialysis initiation. Unemployment (SHR, 0.47; 95% CI, 0.45-0.48) and part-time employment (SHR, 0.74; 95% CI, 0.70-0.77) were associated with lower waitlisting compared with full-time employment, and more than 1 year of predialysis nephrology care, compared with none, was associated with greater waitlisting (SHR, 1.51; 95% CI, 1.46-1.56).

Conclusions and Relevance

This retrospective cohort study found that fewer than one-third of patients without major medical comorbidities were waitlisted for a kidney transplant within 1 year of dialysis initiation, with sociodemographic disparities in waitlisting even in this cohort of young, relatively healthy patients unlikely to have a medical contraindication to transplantation. Transplant policy changes are needed to increase transparency and address structural barriers to waitlist access.

Population Characteristics and Organ Procurement Organization Performance Metrics

Importance

In 2020, the Centers for Medicare & Medicaid Services (CMS) issued a final rule updating the Organ Procurement Organization (OPO) Conditions for Coverage. This rule evaluates OPO performance based on an unadjusted donation rate and an age-adjusted transplant rate; however, neither considers other underlying population differences.

Objective

To evaluate whether adjusting for age and/or area deprivation index yields the same tier assignments as the cause, age, and location consistent (CALC) tier used by CMS.

Design, Setting, and Participants

This retrospective cross-sectional study examined the performance of 58 OPOs from 2018 to 2020 across the entire US. A total of 12 041 778 death records were examined from the 2017 to 2020 National Center for Health Statistics' Restricted Vital Statistics Detailed Multiple Cause of Death files; 399 530 of these met the definition of potential deceased donor. Information about 42 572 solid organ donors from the Scientific Registry of Transplant Recipients was also used. Statistical analysis was performed from January 2017 to December 2020.

Exposure

Area deprivation of donation service areas and age of potential donors.

Main Outcome and Measures

OPO performance as measured by donation and transplant rates.

Results

A total of 399 530 potential deceased donors and 42 572 actual solid donor organs were assigned to 1 of 58 OPOs. Age and ADI adjustment resulted in 19.0% (11 of 58) to 31.0% (18 of 58) reclassification of tier ratings for the OPOs, with 46.6% of OPOs (27 of 58) changing tier ranking at least once during the 3-year period. Between 6.9% (4 of 58) and 12.1% (7 of 58) moved into tier 1 and up to 8.6% (5 of 58) moved into tier 3.

Conclusions and Relevance

This cross-sectional study of population characteristics and OPO performance metrics found that adjusting for area deprivation and age significantly changed OPO measured performance and tier classifications. These findings suggest that underlying population characteristics may alter processes of care and characterize donation and transplant rates independent of OPO performance. Risk adjustment accounting for population characteristics warrants consideration in prospective policy and further evaluation of quality metrics.

New OPTN/UNOS data demonstrates higher than previously reported waitlist mortality for lung transplant candidates supported with ECMO

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) is not currently incorporated into US allocation models due to the historical lack of complete data in the national US registry which changed in 2016 to include ECMO at the time of waitlist removal and more granular timing and configuration data.

METHODS

We studied adult lung transplant candidates from May 1, 2016 to June 1, 2020 with data abstracted from multiple sources in the US Scientific Registry of Transplant Recipients. Waitlist analyses included cumulative incidence functions and Cox proportional hazards models considering ECMO as a time-dependent variable. Post-transplant analyses included Kaplan Meier, Cox proportional hazards models, and observed to expected survival ratios.

RESULTS

A total of 867 candidates were on ECMO prior to transplant; 247 were identified using new sources of data. Candidates on ECMO had a 23.9 increased adjusted likelihood of waitlist removal for being too sick or death, but only a 4.08 increased adjusted likelihood of transplant. Candidates bridged with ECMO who underwent lung transplant (N = 587) experienced an increased overall hazard of post-transplant mortality with veno-arterial and veno-venous configurations conferring hazard ratio (HR) = 1.67 (95% CI, 1.16, 2.40), HR = 1.45 (95% CI, 1.15, 1.82), respectively.

CONCLUSIONS

We identified an additional 28.5% of candidates bridged with ECMO prior to transplant using new data. This study of the newly identified full cohort of ECMO candidates demonstrates higher utilization of ECMO as well as an underestimation of waitlist mortality risk factors that should inform strategies to provide timely access to transplants for this population.

Reassessing the survival benefit of deceased donor liver transplantation: retrospective cohort study

INTRODUCTION

Currently in the United States, deceased donor liver transplant (DDLT) allocation priority is based on the model for end-stage liver disease including sodium (MELD-Na) score. The United Network for organ sharing's 'Share-15' policy states that candidates with MELD-Na scores of 15 or greater have priority to receive local organ offers compared to candidates with lower MELD-Na scores. Since the inception of this policy, major changes in the primary etiologies of end-stage liver disease have occurred and previous assumptions need to be recalibrated.

METHODS

The authors retrospectively analyzed the Scientific Registry of Transplant Recipients database between 2012 and 2021 to determine life years saved by DDLT at each interval of MELD-Na score and the time-to-equal risk and time-to-equal survival versus remaining on the waitlist. The authors stratified our analysis by MELD exception points, primary disease etiology, and MELD score.

RESULTS

On aggregate, compared to remaining on the waitlist, a significant 1-year survival advantage of DDLT at MELD-Na scores as low as 12 was found. The median life years saved at this score after a liver transplant was estimated to be greater than 9 years. While the total life years saved were comparable across all MELD-Na scores, the time-to-equal risk and time-to-equal survival decreased exponentially as MELD-Na scores increased.

CONCLUSION

Herein, the authors challenge the perception as to the timing of DDLT and when that benefit occurs. The national liver allocation policy is transitioning to a continuous distribution framework and these data will be instrumental to defining the attributes of the continuos allocation score.

Lithium and the living kidney donor: Science or stigma?

Nearly 10 000 people are removed from the kidney transplant waiting list each year either due to becoming too ill for transplant or due to death. Live donor kidney transplant (LDKT) provides superior outcomes and survival benefit relative to deceased donor transplant, but the number of LDKT has decreased over the past few years. Therefore, it is of paramount importance that transplant centers employ evaluation processes that safely maximize LDKT. Decisions about donor candidacy should be based on the best available data, rather than on processes prone to bias. Here, we examine the common practice of declining potential donors based solely on treatment with lithium. We conclude that the risk of end-stage renal disease related to lithium treatment is comparable to other generally accepted risks in LDKT. We present this viewpoint to specifically challenge the carte blanche exclusion of individuals taking lithium and highlight the importance of using the best available data relevant to any risk factor, rather than relying on biases, when evaluating potential living kidney donors.

An evaluation of the organ procurement and transplantation network's expanded post-transplant performance metrics

On July 14, 2022, the Organ Procurement and Transplantation Network's (OPTN) Membership and Professional Standards Committee (MPSC) approved bylaws including two new post-transplant performance evaluation metrics, the 90-day (90D) and 1-year conditional on the 90-day (1YC90D) graft survival hazard ratio (HR). These metrics have replaced the previous 1-year (1Y) unconditional, post-transplant graft survival HR and are used to nationally rank and identify programs for MPSC review. The MPSC's policies have major implications for all transplant programs, providers, and patients across the United States. Herein we show two significant limitations with the new evaluation criteria, arbitrary censoring periods and interdependence in the new performance metrics. We have demonstrated a strong and consistent inverse correlation between the new evaluation metrics, thus proving a lack of independence. Moreover, these two evaluation criteria are interdependent even at nominal HRs. Thus, the 90D cohort can be used to accurately predict whether the 1YC90D is above or below a given HR threshold. This could alter practice behaviors and the timing of patient event reporting, which may result in many unintended consequences related to clinical practice. Here we provide the first evidence that this new evaluation system will lead to a significant increase in the number of programs flagged for MPSC review. When this occurs, the cost of operating a transplant program will increase without a clear demonstration of an increased accuracy in identifying problematic programs.

The Organ Shortage Continues to Be a Crisis for Patients With End-stage Kidney Disease

This Viewpoint describes the organ shortage for patients with end-stage kidney disease despite increases in kidney donations between 2000 and 2021.

Urine Sediment Examination: Comparison Between Laboratory-Performed Versus Nephrologist-Performed Microscopy and Accuracy in Predicting Pathologic Diagnosis in Patients with Acute Kidney Injury

Key Points

A nephrologist is more likely to recognize the presence of pathologic casts and dysmorphic red blood cells. Nephrologist-performed urine sediment analysis is also highly accurate in diagnosing acute tubular injury or glomerulonephritis when compared with kidney biopsy.

Introduction

Automated urine technology is becoming the standard for urinalysis microscopy. We sought to compare urine sediment analysis performed by a nephrologist with the analysis performed by the laboratory. When available, we also compared the suggested diagnosis per nephrologists' sediment analysis with the biopsy diagnosis.

Methods

We identified patients with AKI who had urine microscopy with sediment analysis performed by the laboratory (Laboratory-UrSA) and by a nephrologist (Nephrologist-UrSA) within 72 hours of each other. We collected data to determine the following: number of red blood cells (RBCs) and white blood cells (WBCs) per high-power field, presence and types of casts per low-power field, and presence of dysmorphic RBCs. We evaluated agreement between the Laboratory-UrSA and the Nephrologist-UrSA using cross-tabulation and the Kappa statistic. When available, we categorized the nephrologist sediment findings into four categories: (1) bland, (2) suggestive of acute tubular injury (ATI), (3) suggestive of glomerulonephritis (GN), and (4) suggestive of acute interstitial nephritis (AIN). In a group of patients with kidney biopsy within 30 days of the Nephrologist-UrSA, we assessed agreement between the nephrologist diagnosis and the biopsy diagnosis.

Results

We included 387 patients with both Laboratory-UrSA and Nephrologist-UrSA. The agreement was moderate for the presence of RBCs (Kappa, 0.46; 95% CI, 0.37 to 0.55) and fair for WBCs (Kappa, 0.36; 95% CI, 0.27 to 0.45). There was no agreement for casts (Kappa, 0.026; 95% CI, −0.04 to 0.07). Eighteen dysmorphic RBCs were detected on Nephrologist-UrSA compared with zero on Laboratory-UrSA. Among the 33 patients with kidney biopsy, 100% ATI and 100% GN suggested per Nephrologist-UrSA were confirmed on the biopsy. Of the five patients with bland sediment on the Nephrologist-UrSA, 40% showed ATI pathologically while the other 60% demonstrated GN.

Conclusion

A nephrologist is more likely to recognize the presence of pathologic casts and dysmorphic RBCs. Correct identification of these casts carries important diagnostic and prognostic value when evaluating kidney disease.

The promise and reality of machine-learning models in kidney transplantation

There have been numerous advances in statistical methods and computing technologies over the past decades, including the use of machine-learning models. In the current study, Truchot et al. rigorously evaluated the performance of different machine-learning models compared with traditional Cox proportional hazard models. Results of the study indicated that a Cox model had equivalent or superior performance than machine-learning models and can be relied on for predicting graft survival in kidney transplantation.

A model for calculating the long-term estimated post-transplant survival of deceased donor liver transplant patients

BACKGROUND

The estimated long-term survival (EPTS) score is used for kidney allocation. A comparable prognostic tool to accurately quantify EPTS benefit in deceased donor liver transplant (DDLT) candidates is nonexistent.

METHODS

Using the Scientific Registry of Transplant Recipients (SRTR) database, we developed, calibrated, and validated a nonlinear regression equation to calculate liver-EPTS (L-EPTS) for 5- and 10-year outcomes in adult DDLT recipients. The population was randomly split (70:30) into two discovery (N = 26,372 and N = 46,329) and validation cohorts (N = 11,288 and N = 19,859) for 5- and 10-year post-transplant outcomes, respectively. Discovery cohorts were used for variable selection, Cox proportional hazard regression modeling, and nonlinear curve fitting. Eight clinical variables were selected to construct the L-EPTS formula, and a five-tiered ranking system was created.

FINDINGS

Tier thresholds were defined and the L-EPTS model was calibrated (R² = 0.96 [5-year] and 0.99 [10-year]). Patients' median survival probabilities in the discovery cohorts for 5- and 10-year outcomes ranged from 27.94% to 89.22% and 16.27% to 87.97%, respectively. The L-EPTS model was validated via calculation of receiver operating characteristic (ROC) curves using validation cohorts. Area under the ROC curve was 82.4% (5-year) and 86.5% (10-year).

INTERPRETATION

L-EPTS has high applicability and clinical utility because it uses easily obtained pre-transplant patients characteristics to accurately discriminate between those who are likely to receive a prolonged survival benefit and those who are not. It is important to evaluate medical urgency alongside survival benefit and placement efficiency when considering the allocation of a scarce resource.

FUNDING

There are no funding sources related to this project.

Contribution of Estimates of Glomerular Filtration to the Extensive Disparities in Preemptive Listing for Kidney Transplant

Introduction

The use of race coefficients in equations for estimated glomerular filtration rate (eGFR) may have contributed to racial disparities in access to preemptive (without dialysis exposure) kidney transplantation (Ktx).

Methods

In this retrospective national cohort study of incident kidney transplant candidates in the United States from 2001 to 2019, we describe temporal trends and racial disparities in preemptive listing and the distribution of eGFR at listing, using eGFR as reported and after removing the race coefficient for Black candidates.

Results

Among 511,686 candidates, preemptive listing increased over time, from 18% in 2001 to 33% in 2019. Non-Black candidates were listed preemptively nearly twice as frequently as Black candidates in 2019 (38% vs. 21% preemptive) and at higher eGFR values (median 15.6 vs. 15.0 ml/min per 1.73 m²). After adjusting for candidate characteristics, including listing eGFR without the race coefficient, preemptive Black candidates still had significantly lower odds of preemptive deceased donor (DD) kidney transplantation compared to non-Black candidates (odds ratio 0.87, 95% confidence interval: 0.78-0.98).

Conclusions

Over the last 2 decades, Black patients were consistently less likely to be listed preemptively and were listed at lower eGFR values. Adjusting for listing eGFR with the race coefficient computationally removed did not eliminate the racial disparity, suggesting that additional efforts are needed to achieve equity in preemptive transplantation beyond adopting race-free eGFR equations.