Characteristics of compatible pair participants in kidney paired donation at a single center

Artificial intelligence assisted risk prediction in organ transplantation: a UK Live-Donor Kidney Transplant Outcome Prediction tool

Introduction: Predicting the outcome of a kidney transplant involving a living donor advances donor decision-making donors for clinicians and patients. However, the discriminative or calibration capacity of the currently employed models are limited. We set out to apply artificial intelligence (AI) algorithms to create a highly predictive risk stratification indicator, applicable to the UK's transplant selection process.

Methodology: Pre-transplant characteristics from 12,661 live-donor kidney transplants (performed between 2007 and 2022) from the United Kingdom Transplant Registry database were analyzed. The transplants were randomly divided into training (70%) and validation (30%) sets. Death-censored graft survival was the primary performance indicator. We experimented with four machine learning (ML) models assessed for calibration and discrimination [integrated Brier score (IBS) and Harrell's concordance index]. We assessed the potential clinical utility using decision curve analysis.

Results: XGBoost demonstrated the best discriminative performance for survival (area under the curve = 0.73, 0.74, and 0.75 at 3, 7, and 10 years post-transplant, respectively). The concordance index was 0.72. The calibration process was adequate, as evidenced by the IBS score of 0.09.

Conclusion: By evaluating possible donor-recipient pairs based on graft survival, the AI-based UK Live-Donor Kidney Transplant Outcome Prediction has the potential to enhance choices for the best live-donor selection. This methodology may improve the outcomes of kidney paired exchange schemes. In general terms we show how the new AI and ML tools can have a role in developing effective and equitable healthcare.

Advantages of the single-center model in domino transplant processes: Operational planning and management experience

BACKGROUND

Kidney transplantation is one of the most effective treatments for patients with end-stage renal disease. However, many regions face low deceased donor rates and limited ABO-compatible transplant availability, which increases reliance on living donors. These regional challenges necessitate the implementation of kidney paired donation (KPD) programs to overcome incompatibilities such as ABO mismatch or positive cross-matching, even when suitable and willing donors are available.

AIM

To evaluate the effectiveness of a single-center domino KPD model in both operational planning and clinical management processes and to assess its impact on clinical outcomes.

METHODS

Between April 2020 and January 2024, we retrospectively evaluated patients enrolled in our center’s domino kidney transplantation program. Donor-recipient pairs unable to proceed due to ABO incompatibility or positive cross-matching with their own living donors were included. Donors and recipients were assessed based on blood group compatibility, HLA tissue typing, and negative cross-match results. A specialized computer algorithm grouped patients into three-way, four-way, and five-way chains. All surgical procedures were performed on the same day at a single center.

RESULTS

A total of 169 kidney transplants were performed, forming 52 domino chains. These domino KPD transplants accounted for a notable proportion of our center’s overall transplant activity, which included both living donor kidney transplants and deceased donor transplants. Among these chains, the primary reasons for participation were ABO incompatibility (74%), positive cross-matching (10%), and the desire to improve HLA mismatch (16%). Improved HLA mismatch profiles and high graft survival (96% at 1 year, 92% at 3 years) and patient survival (98% at 1 year, 94% at 3 years) rates were observed, as well as low acute rejection episodes.

CONCLUSION

The single-center domino KPD model enhanced transplant opportunities for incompatible donor-recipient pairs while maintaining excellent clinical outcomes. By providing a framework that addresses regional challenges, improves operational efficiency, and optimizes clinical management, this model offers actionable insights to reduce waiting lists and improve patient outcomes.

Mitigating High-risk EBV and CMV Through Kidney Paired Donation: A Survey of Potential Donor and Recipient Candidates

Background

High-risk cytomegalovirus (CMV) and Epstein-Barr virus (EBV) mismatches (ie, seropositive donors to seronegative recipients) among kidney transplant recipients lead to increased healthcare utilization, inferior allograft outcomes, and high mortality. We assessed the interest among prospective kidney donor and recipient candidates to participate in kidney paired donation (KPD) for averting CMV/EBV high-risk mismatches.

Methods

We surveyed 51 potential living donors and 102 kidney recipient candidates presenting for their evaluation visit at the University of Pittsburgh Medical Center between October 2022 and May 2023. We evaluated their general inclination toward KPD and their interest in KPD under various risk-benefit scenarios, particularly emphasizing the mitigation of high-risk mismatches associated with EBV and CMV. This was done using a 5-point Likert scale (1-low interest; 5-high interest) customized survey.

Results

There was high interest in KPD among both donor and recipient candidates (median score 4 versus 4; P = 0.09). However, donor candidates had a lower interest in KPD if they were compatible with their intended recipient (median score 2 versus 4; P < 0.001). Most donor (80.4%; N = 41) and recipient candidates (89.2%; N = 91) expressed a strong willingness to participate in KPD to prevent high-risk CMV and EBV mismatches, but this interest declined with longer transplant delays. Interest also varied on the basis of participants' income and employment status.

Conclusions

Interest in KPD for avoiding CMV and EBV was high among both donor and recipient candidates. Additional research is required to assess the capacity and desirability for KPD expansion, particularly among ABO and HLA-compatible pairs.

Liver paired exchange: A US single-center experience-Pairs, chains, and use of compatible pairs

In the United States, the discrepancy between organ availability and need has persisted despite changes in allocation, innovations in preservation, and policy initiatives. Living donor liver transplant remains an underutilized means of improving access to timely liver transplantation and decreasing waitlist mortality. Liver paired exchange (LPE) represents an opportunity to overcome living donor liver transplant pair incompatibility due to size, anatomy, or blood type. LPE was adopted as a strategy to augment access to liver transplantation at our institution. Specific educational materials, consent forms, and selection processes were developed to facilitate LPE. From 2019 through October 2023, our center performed 11 LPEs, resulting in 23 living donor liver transplant pairs. The series included several types of LPE: those combining complementary incompatible pairs, the inclusion of compatible pairs to overcome incompatibility, and the use of altruistic nondirected donors to initiate chains. These exchanges facilitated transplantation for 23 recipients, including 1 pediatric patient. LPE improved access to liver transplantation at our institution. The ethical application of LPE includes tailored patient education, assessment and disclosure of exchange balance, mitigation of risk, and maximization of benefit for donors and recipients.

The living kidney donor profile index fails to discriminate allograft survival: implications for its use in kidney paired donation programs

The inclusion of blood group- and human leukocyte antigen-compatible donor and recipient pairs (CPs) in kidney paired donation (KPD) programs is a novel strategy to increase living donor (LD) transplantation. Transplantation from a donor with a better Living Donor Kidney Profile Index (LKDPI) may encourage CP participation in KPD programs. We undertook parallel analyses using data from the Scientific Registry of Transplant Recipients and the Australia and New Zealand Dialysis and Transplant Registry to determine whether the LKDPI discriminates death-censored graft survival (DCGS) between LDs. Discrimination was assessed by the following: (1) the change in the Harrell C statistic with the sequential addition of variables in the LKDPI equation to reference models that included only recipient factors and (2) whether the LKDPI discriminated DCGS among pairs of prognosis-matched LD recipients. The addition of the LKDPI to reference models based on recipient variables increased the C statistic by only 0.02. Among prognosis-matched pairs, the C statistic in Cox models to determine the association of the LKDPI with DCGS was no better than chance alone (0.51 in the Scientific Registry of Transplant Recipient and 0.54 in the Australia and New Zealand Dialysis and Transplant Registry cohorts). We conclude that the LKDPI does not discriminate DCGS and should not be used to promote CP participation in KPD programs.

Living donor kidney paired exchange: An observational study

Background

Kidney transplantation is the treatment of choice for patients with end-stage renal disease (ESKD). Kidney paired donation (KPD) provides the chance to match an incompatible donor/recipient pair with another donor and recipient in a similar condition. We aimed to compare the outcomes of pair exchange kidney transplantation with traditional live donor kidney transplantation in our context.

Method

A review of medical records of 62 patients (31 pairs) who underwent two-way conventional living kidney pair exchange from July 2016 to June 2021 was done. The control group was considered those 62 patients who had undergone classic live donor kidney transplantation (LDKT) during the study period. The patient's demographics, intraoperative and postoperative variables including delayed graft function, length of hospital stay, graft survival, patient survival, and rejections rates were compared between the groups (KPD and LDKT).

Results

The majority of recipients were male (77.4 and 80.6%) while donors were female (77.4 and 69.4%) in KPD and the LDKT groups. Mean ages were 37 years (range: 19–59) and 37 years (range: 17–65) for the recipient's in KPD and the LDKT. KPD transplantation was performed in 62 recipients to avoid blood group incompatibility. There were no significant differences in outcomes comprising delayed graft function (1.6 and 3.2%), graft survival (100% in both groups), patient survival (95.2 and 96.8%), and rejections rates (1.6 and 1.6%) between KPD and LDKT group (P > 0.005). The length of stay was similar (5.9 and 5.7 days) in KPD and LDKT groups (P > 0.005).

Conclusions

The outcomes of KPD were comparable with classic LDKT in terms of delayed graft function, length of hospital stay, graft survival, patient survival, and rejections rates in our study. Therefore, the kidney paired donation program should be encouraged and promoted in centers where the ABO-incompatible transplant is expensive with added risk and the rate of deceased donor transplantation is very low.

•

Kidney paired donation (KPD) provides the chance to match for an incompatible donor/recipient pair with another donor and recipient in a similar condition.

•

The outcomes of KPD were comparable with classic live donor kidney transplantation (LDKT) in this study.

•

KPD program should be promoted in centers where the ABO incompatible transplant is expensive with added risk and the rate of deceased donor transplantation is very low.

Rethinking incompatibility in kidney transplantation

Donor/recipient incompatibility in kidney transplantation classically refers to ABO/HLA-incompatibility. Kidney paired donation (KPD) was historically established to circumvent ABO/HLA-incompatibility, with the goal of identifying ABO/HLA-compatible matches. However, there is a broad range of donor factors known to impact recipient outcomes beyond ABO/HLA-incompatibility, such as age and weight, and quantitative tools are now available to empirically compare potential living donors across many of these factors, such as the living donor kidney donor profile index (LKDPI). Moreover, the detrimental impact of mismatch at other HLA antigens (such as DQ) and epitope mismatching on posttransplant outcomes has become increasingly recognized. Thus, it is time for a new paradigm of incompatibility that considers all of these risks factors together in assessing donor/recipient compatibility and the potential utility for KPD. Under this new paradigm of incompatibility, we show how the LKDPI and other tools can be used to identify donor/recipient incompatibilities that could be improved through KPD, even for those with a traditionally "compatible" living donor.

Motivations and outcomes of compatible living donor-recipient pairs in paired exchange

Increasing numbers of compatible pairs are choosing to enter paired exchange programs, but motivations, outcomes, and system-level effects of participation are not well described. Using a linkage of the Scientific Registry of Transplant Recipients and National Kidney Registry, we compared outcomes of traditional (originally incompatible) recipients to originally compatible recipients using the Kaplan-Meier method. We identified 154 compatible pairs. Most pairs sought to improve HLA matching. Compared to the original donor, actual donors were younger (39 vs. 50 years, p < .001), less often female (52% vs. 68%, p < .01), higher BMI (27 vs. 25 kg/m², p = .03), less frequently blood type O (36% vs. 80%, p < .001), and had higher eGFR (99 vs. 94 ml/min/1.73 m², p = .02), with a better LKDPI (median 7 vs. 22, p < .001). We observed no differences in graft failure or mortality. Compatible pairs made 280 additional transplants possible, many in highly sensitized recipients with long wait times. Compatible pair recipients derived several benefits from paired exchange, including better donor quality. Living donor pairs should receive counseling regarding all options available, including kidney paired donation. As more compatible pairs choose to enter exchange programs, consideration should be given to optimizing compatible pair and hard-to-transplant recipient outcomes.

Compatible Donor and Recipient Pairs' Perspectives on Participation in Kidney Paired Donation Programs: A Mixed-Methods Study

Background:

Compatible pair participation in kidney paired donation (KPD) may increase the likelihood of finding suitable matches for all registered pairs. Retrospective studies have shown variable enthusiasm for participating in KPD in compatible pairs.

Objective:

The study objective was to gather potential living donor (PLD) and transplant candidate (TC) perspectives on compatible pair participation in KPD.

Design:

Surveys and qualitative interviews.

Setting:

Three transplant programs in Canada: Centre hospitalier de l’Université de Montréal in Montreal (Québec), Vancouver General Hospital, and St. Paul’s Hospital in Vancouver (British Columbia).

Patients:

Both PLDs and TCs undergoing evaluation for donation/transplantation between 2016 and 2018 at 3 transplant programs in Canada.

Methods:

Descriptive statistical analysis was performed for the results of the survey and thematic and content analysis method was used for the content of the qualitative interviews.

Results:

A total of 116 PLDs and 111 TCs completed surveys and an additional 18 PLDs and 17 TCs underwent semi-directed interviews. Of those surveyed, 61.2% of PLDs and 76.6% of TCs reported a willingness to participate in KPD as a compatible pair. The possibility of a more optimally matched kidney for the TC and policies ensuring prioritization of the TC for repeat transplantation in the event of early graft failure increased willingness to participate in KPD. Major concerns expressed during the interviews included the desire to retain the emotional bond of directed donation, the fear of chain breaks or donor reneging, delays in transplantation, and additional travel associated with participation in KPD.

Limitation:

The limitations of this study are that it was conducted in only 3 Canadian transplant programs and that the interviews and surveys were in French and in English. As a consequence, the results may not be reflective of the views of individuals not living in these 2 provinces and from ethnic minority populations.

Conclusion:

Most of the compatible PLDs and TCs surveyed were willing to participate in KPD. Ensuring timely transplantation and a more optimal match for TCs and offering a policy of reciprocity to ensure timely repeat transplantation for compatible recipients if their allograft fails post KPD transplant may further increase compatible pair participation in KPD.

The Potential Significance of ABO Genotyping for Donor Selection in Kidney Transplantation

Background

The ABO blood group system is clinically important in kidney transplantation, but ABO genotyping fails to attract sufficient attention in some countries and regions. We identified one case of early graft dysfunction due to an ABO genotype mismatch. Here, we performed ABO genotyping in blood samples, analyzed grouping discrepancies, and investigated the weak A subgroup frequency in kidney transplantation candidates.

Methods

Blood samples from 302 uremic patients with grouping discrepancies and 356 uremic patients with type A blood were analyzed using standard serologic serotyping techniques. The ABO genotypes and alleles were analyzed by polymerase chain reaction sequence-specific primer (PCR-SSP) and sequence-based typing (PCR-SBT).

Results

All 302 uremic patients with grouping discrepancies carried weak ABO subgroup alleles and 77.48% carried irregular ABO antibodies. The discrepancy rate between serotyping and genotyping was 42.38%, and the mismatching rate of donor selection according to serotype reached 88.74%. And 2.53% of 356 uremic patients with type A blood were determined to be in the weak A subgroup, which was a higher percentage than that observed in the healthy Chinese population (0.53%) by serological screening, but much lower than that observed in Caucasians (20%).

Conclusion

We revealed the high risk of blood type misjudgment and genetically ABO-mismatched transplantation if serological test was performed only in blood-group typing. Improved precision of ABO genotyping is crucial for successful kidney transplantation and reasonable organ allocation.

Ten Years of Kidney Paired Donation at Mayo Clinic: The Benefits of Incorporating ABO/HLA Compatible Pairs

BACKGROUND

We examined the 10-year experience of Mayo Clinic's kidney paired donation (KPD).We aimed to determine the benefits for the recipients of enrolled ABO/HLA compatible pairs and determine the factors associated with prolonged KPD waiting time.

METHODS

We performed a retrospective study of 332 kidney transplants facilitated by the Mayo 3-site KPD program from September 2007 to June 2018.

RESULTS

The median (interquartile range) time from KPD entry to transplantation was 89 days (42-187 days). The factors independently associated with receiving a transplant >3 months after KPD entry included recipient blood type O and calculated panel reactive antibodies ≥98%. Fifty-four ABO/HLA compatible pairs participated in KPD for the following reasons: cytomegalovirus mismatch (18.5% [10/54]), Epstein-Barr virus (EBV) mismatch (EBV) (9.3% [5/54]), age/size mismatch (51.9% [28/54]), or altruistic reasons (20.3% [11/54]). Cytomegalovirus and EBV mismatch were avoided in 90% (9/10) and 100% (5/5) of cases. Recipients who entered KPD for age/size mismatch and altruistic reasons received kidneys from donors with lower Living Kidney Donor Profile Index scores than their actual donor (median [interquartile range] 31.5 [12.3-47]; P < 0.001 and 26 (-1 to 46); P = 0.01 points lower, respectively). Median time to transplant from KPD entry for compatible pair recipients was 70 days (41-163 days), and 44.4% (24/54) of these transplants were preemptive. All chains/swaps incorporating compatible pairs included ABO/HLA incompatible pairs.

CONCLUSIONS

KPD should be considered for all living donor/recipient pairs because the recipients of these pairs can derive personal benefit from KPD while increasing the donor pool for difficult to match pairs.