The broad spectrum of quality in deceased donor kidneys

Clinical significance of the living kidney donor profile index for predicting long-term posttransplant outcomes: results from the Korean Organ Transplantation Registry

BACKGROUND

The usefulness of the living kidney donor profile index (LKDPI) has not been widely demonstrated; therefore, it requires verification before clinical application. We analyzed the LKDPI using data from the Korean Organ Transplantation Registry (KOTRY) to confirm whether the LKDPI can be used to predict the survival of allografts in living donor kidney transplantation (LDKT) patients in Korea.

METHODS

The study population was obtained from the KOTRY database. A total of 2,598 kidney recipients registered in the KOTRY database were enrolled between May 2014 and December 2020. Donor and recipient information was observed, and the LKDPI was measured.

RESULTS

Median LKDPI score was 15.5 with a follow-up duration of 33.7 ± 16.1 months. According to LKDPI scores (group 1, <0; group 2, 0-20; group 3, 20-40; and group 4, >40), LKDPI group 4 had significantly higher death-censored graft loss than LKDPI group 1 (hazard ratio [HR], 1.89; 95% confidence interval [CI], 1.06- 3.40; p = 0.03). When divided based on the cutoff value (LKDPI, 36.6), the high LKDPI group had higher graft loss than the low LKDPI group (HR, 2.14; 95% CI, 1.37-3.34; p < 0.001). When follow-up was repeated after transplantation, it was confirmed that the higher the LKDPI value was, the lower the average estimated glomerular filtration rate (p < 0.001).

CONCLUSION

This study confirmed that LKDPI can serve as an independent predictor for assessing the risk of allograft failure and transplant outcomes in Korean LDKT patients.

A Prognostic Index for Deceased Donor Kidneys and Criteria for Identifying Suitable Candidates for Kidney Transplantation from Expanded Criteria Donors with Prolonged Waiting Times

Introduction

The kidney donor profile index (KDPI) is a valuable prognostic tool in deceased donor kidney transplantation (DDKT), while its optimization for each country using local data is essential. It remains unclear which patients derive survival benefits from expanded criteria donor (ECD) DDKT compared to waitlist or standard criteria donor (SCD) DDKT, particularly in the context of long waiting times. This study aimed to develop a prognostic index for donor kidneys and propose criteria to identify suitable candidates for ECD DDKT in Korea.

Methods

Two prediction models were developed using data from two cohorts based on national databases (the Korean Network for Organ Sharing and the National Health Insurance Data Sharing Service): cohort for the prediction of graft prognosis (n = 6,272) and cohort for the prediction of suitable candidates for ECD DDKT (n = 30,183).

Results

The Korean KDPI (K-KDPI) comprises five donor factors (age, height, diabetes mellitus, serum creatinine levels, and hepatitis C virus), associated with graft failure. The discriminatory ability of the K-KDPI for graft outcomes surpassed that of the US KDPI and dichotomous ECD criteria. ECD kidneys (K-KDPI ≥70%) showed worse allograft survival compared to SCD kidneys (K-KDPI <70%). Candidates aged ≥40 years, with negative panel reactive antibody, and without diabetes mellitus had a significantly lower mortality risk with ECD DDKT than with waitlist-or-SCD DDKT, making them suitable for ECD DDKT.

Conclusion

The K-KDPI and criteria for identifying suitable ECD recipients are expected to improve the quality assessment and efficient utilization of ECD kidneys in Korea with long waiting times.

2-Step Scores with optional nephropathology for the prediction of adverse outcomes for brain-dead donor kidneys in Eurotransplant

BACKGROUND

The decision to accept or discard the increasingly rare and marginal brain-dead donor kidneys in Eurotransplant (ET) countries has to be made without solid evidence. Thus, we developed and validated flexible clinicopathological scores called 2-Step Scores for the prognosis of delayed graft function (DGF) and 1-year death-censored transplant loss (1y-tl) reflecting the current practice of six ET countries including Croatia and Belgium.

METHODS

The training set was n = 620 for DGF and n = 711 for 1y-tl, with validation sets n = 158 and n = 162, respectively. In Step 1, stepwise logistic regression models including only clinical predictors were used to estimate the risks. In Step 2, risk estimates were updated for statistically relevant intermediate risk percentiles with nephropathology.

RESULTS

Step 1 revealed an increased risk of DGF with increased cold ischaemia time (CIT), donor and recipient body mass index, dialysis vintage, number of HLA-DR mismatches or recipient cytomegalovirus immunoglobulin G positivity. On the training and validation set, c-statistics were 0.672 and 0.704, respectively. At a range between 18% and 36%, accuracy of DGF-prognostication improved with nephropathology including number of glomeruli and Banff cv (updated overall c-statistics of 0.696 and 0.701, respectively). Risk of 1y-tl increased in recipients with CIT, sum of HLA-A, -B, -DR mismatches, and donor age. On training and validation sets, c-statistics were 0.700 and 0.769, respectively. Accuracy of 1y-tl prediction improved (c-statistics = 0.706 and 0.765) with Banff ct. Overall, calibration was good on the training, but moderate on the validation set; discrimination was at least as good as established scores when applied to the validation set.

CONCLUSION

Our flexible 2-Step Scores with optional inclusion of time-consuming and often unavailable nephropathology should yield good results for clinical practice in ET, and may be superior to established scores. Our scores are adaptable to donation after cardiac death and perfusion pump use.

Adjusted Donor Age: A Clinical Score to Support Organ Acceptance Decisions in Deceased-Donor Kidney Transplantation

As transplant programmes have evolved to allow a wider donor pool, organ acceptance decisions have become increasingly complex and lack transparency and equality. Clinical scoring tools exist but there is limited consensus on their use. From a prospective observation of consecutive deceased-donor kidney offers in a large urban transplant centre, a simple score was developed based on donor age and other risk characteristics, excluding ischemia time and graft histology. The score was validated in subsequent cohorts of consecutive offers in the United Kingdom and Germany. In the development cohort of 389 kidney offers, 110 (28%) were transplanted and 175 (45%) declined. Nine risk factors were incorporated into a score based on age, but adjusted for the number of risk factors present, making an "adjusted donor age," with offers separated into equal quintiles by decade. The score was validated in a UK cohort of 380 subsequent offers, and a German cohort of 431 offers. In both cohorts adjusted donor age discriminated between favourable and poor post-transplant outcomes (C-statistic 0.77 in the United Kingdom, 95% CI 0.65-0.88, and 0.71 in Germany, 95% CI 0.64-0.77). Adjusted donor age is a simple score quantifying deceased donor kidney quality, which is consistent with current practice and predicts post-transplant outcome.

Kidney Utilization in the Context of a Shifting Donor Landscape in the United States

BACKGROUND

In 2021, 24.6% of kidneys procured in the United States were not utilized. This study examines trends in kidney graft nonutilization within the context of shifting donor demographics and procurement practices.

METHODS

We analyzed data from the Standard Transplant Analysis and Research data set, spanning deceased donors from 1988 to the present, provided by the Organ Procurement and Transplantation Network. Linear regression was used to estimate changes in organ utilization over time.

RESULTS

During the past 40 y, the quality of donor kidneys decreased as measured by the mean Kidney Donor Risk Index (KDRI), which increased from 1.20 to 1.43. Currently, 13% of kidneys procured have a KDRI >2, with an 81% nonutilization rate. Despite the increase in high-risk graft procurement, the overall growth in kidney recoveries and utilization has increased.

CONCLUSIONS

The volume of kidney transplants has grown alongside an increasing KDRI in the donor population, which led to a concurrent rise in nonutilization rates. Nevertheless, transplant volumes and 1-y graft outcomes have shown continuous improvement, underscoring the resilience of the transplantation system despite the evolving donor landscape.

Scoring donor lungs for graft failure risk: The Lung Donor Risk Index (LDRI)

Lung transplantation lags behind other solid organ transplants in donor lung utilization due, in part, to uncertainty regarding donor quality. We sought to develop an easy-to-use donor risk metric that, unlike existing metrics, accounts for a rich set of donor factors. Our study population consisted of n = 26 549 adult lung transplant recipients abstracted from the United Network for Organ Sharing Standard Transplant Analysis and Research file. We used Cox regression to model graft failure (GF; earliest of death or retransplant) risk based on donor and transplant factors, adjusting for recipient factors. We then derived and validated a Lung Donor Risk Index (LDRI) and developed a pertinent online application (https://shiny.pmacs.upenn.edu/LDRI_Calculator/). We found 12 donor/transplant factors that were independently predictive of GF: age, race, insulin-dependent diabetes, the difference between donor and recipient height, smoking, cocaine use, cytomegalovirus seropositivity, creatinine, human leukocyte antigen (HLA) mismatch, ischemia time, and donation after circulatory death. Validation showed the LDRI to have GF risk discrimination that was reasonable (C = 0.61) and higher than any of its predecessors. The LDRI is intended for use by transplant centers, organ procurement organizations, and regulatory agencies and to benefit patients in decision-making. Unlike its predecessors, the proposed LDRI could gain wide acceptance because of its granularity and similarity to the Kidney Donor Risk Index.

The Puzzle of Preimplantation Kidney Biopsy Decision-Making Process: The Pathologist Perspective

Kidney transplantation is the best treatment for end-stage renal disease since it offers the greatest survival benefit compared to dialysis. The gap between the number of renal transplants performed and the number of patients awaiting renal transplants leads to a steadily increasing pressure on the scientific community. Kidney preimplantation biopsy is used as a component of the evaluation of organ quality before acceptance for transplantation. However, the reliability and predictive value of biopsy data are controversial. Most of the previously proposed predictive models were not associated with graft survival, but what has to be reaffirmed is that histologic examination of kidney tissue can provide an objective window on the state of the organ that cannot be deduced from clinical records and renal functional studies. The balance of evidence indicates that reliable decisions about donor suitability must be made based on the overall picture. This work discusses recent trends that can reduce diagnostic timing and variability among players in the decision-making process that lead to kidney transplants, from the pathologist's perspective.

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.

Performance of Scores Predicting Adverse Outcomes in Procurement Kidney Biopsies From Deceased Donors With Organs of Lower-Than-Average Quality

Several scores have been devised for providing a prognosis of outcomes after kidney transplantation. This study is a comprehensive test of these scores in a cohort of deceased donors with kidneys of lower-than-average quality and procurement biopsies. In total, 15 scores were tested on a retrospective cohort consisting of 221 donors, 223 procurement biopsies, and 223 recipient records for performance on delayed graft function, graft function, or death-censored graft loss. The best-performing score for DGF was the purely clinical Chapal score (AUC 0.709), followed by the Irish score (AUC 0.684); for graft function, the Nyberg score; and for transplant loss, the Snoeijs score (AUC 0.630) and the Leuven scores (AUCs 0.637 and 0.620). The only score with an acceptable performance was the Chapal score. Its disadvantage is that knowledge of the cold ischemia time is required, which is not known at allocation. None of the other scores performed acceptably. The scores fared better in discarded kidneys than in transplanted kidneys. Our study shows an unmet need for practical prognostic scores useful at the time of a decision about discarding or accepting deceased donor kidneys of lower-than-average quality in the Eurotransplant consortium.

Peri-Operative Kinetics of Plasma Mitochondrial DNA Levels during Living Donor Kidney Transplantation

During ischemia and reperfusion injury (IRI), mitochondria may release mitochondrial DNA (mtDNA). mtDNA can serve as a propagator of further injury but in specific settings has anti-inflammatory capacities as well. Therefore, the aim of this study was to study the perioperative dynamics of plasma mtDNA during living donor kidney transplantation (LDKT) and its potential as a marker of graft outcome. Fifty-six donor-recipient couples from the Volatile Anesthetic Protection of Renal Transplants-1 (VAPOR-1) trial were included. Systemic venous, systemic arterial, and renal venous samples were taken at multiple timepoints during and after LDKT. Levels of mtDNA genes changed over time and between vascular compartments. Several donor, recipient, and transplantation-related variables significantly explained the course of mtDNA genes over time. mtDNA genes predicted 1-month and 24-month estimated glomerular filtration rate (eGFR) and acute rejection episodes in the two-year follow-up period. To conclude, mtDNA is released in plasma during the process of LDKT, either from the kidney or from the whole body in response to transplantation. While circulating mtDNA levels positively and negatively predict post-transplantation outcomes, the exact mechanisms and difference between mtDNA genes are not yet understood and need further exploration.

Values of Donor Serum Lipids and Calcium in Predicting Graft Function after Kidney Transplantation: A Retrospective Study

OBJECTIVE

Delayed graft function (DGF) and early graft loss of renal grafts are determined by the quality of the kidneys from the deceased donor. As "non-traditional" risk factors, serum biomarkers of donors, such as lipids and electrolytes, have drawn increasing attention due to their effects on the postoperative outcomes of renal grafts. This study aimed to examine the value of these serum biomarkers for prediction of renal graft function.

METHODS

The present study consecutively collected 306 patients who underwent their first single kidney transplantation (KT) from adult deceased donors in our center from January 1, 2018 to December 31, 2019. The correlation between postoperative outcomes [DGF and abnormal serum creatinine (SCr) after 6 and 12 months] and risk factors of donors, including gender, age, body mass index (BMI), past histories, serum lipid biomarkers [cholesterol, triglyceride, high-density lipoprotein (HDL) and low-density lipoprotein (DL)], and serum electrolytes (calcium and sodium) were analyzed and evaluated.

RESULTS

(1) Donor age and pre-existing hypertension were significantly correlated with the incidence rate of DGF and high SCr level (≥2 mg/dL) at 6 and 12 months after KT (P<0.05); (2) The donor's BMI was significantly correlated with the incidence rate of DGF after KT (P<0.05); (3) For serum lipids, merely the low level of serum HDL of the donor was correlated with the reduced incidence rate of high SCr level at 12 months after KT [P<0.05, OR (95% CI): 0.425 (0.202-0.97)]; (4) The serum calcium of the donor was associated with the reduced incidence rate of high SCr level at 6 and 12 months after KT [P<0.05, OR (95% CI): 0.184 (0.045-0.747) and P<0.05, OR (95% CI): 0.114 (0.014-0.948), respectively].

CONCLUSION

The serum HDL and calcium of the donor may serve as predictive factors for the postoperative outcomes of renal grafts after KT, in addition to the donor's age, BMI and pre-existing hypertension.

Low skeletal muscle mass is associated with mortality in kidney transplant recipients

Muscle wasting in chronic kidney disease is associated with increased cardiovascular events, morbidity, and mortality. However, whether pretransplantation skeletal muscle mass affects kidney transplantation (KT) outcomes has not been established. We analyzed 623 patients who underwent KT between 2004 and 2019. We measured the cross-sectional area of total skeletal muscle at the third lumbar vertebra level on pretransplantation computed tomography scan. The patients were grouped into low and normal skeletal muscle mass groups based on the sex-specific skeletal muscle mass index lowest quartile. During the entire follow-up period, 45 patients (7.2%) died and 56 patients (9.0%) experienced death-censored graft loss. Pretransplantation low skeletal muscle mass was independently associated with all-cause mortality (adjusted hazard ratio, 2.269; 95% confidence interval, 1.232-4.182). Low muscle mass was also associated with an increased risk of hospital readmission within 1 year after transplantation. Death-censored graft survival rates were comparable between the 2 groups. The low muscle group showed higher creatinine-based estimated glomerular filtration rates (eGFRs) than the normal muscle group. Although cystatin C-based eGFRs were measured in only one-third of patients, cystatin C-based eGFRs were comparable between the 2 groups. Pretransplantation low skeletal muscle mass index is associated with an increased risk of mortality and hospital readmission after KT.

A Review of Current and Emerging Trends in Donor Graft-Quality Assessment Techniques

The number of patients placed on kidney transplant waiting lists is rapidly increasing, resulting in a growing gap between organ demand and the availability of kidneys for transplantation. This organ shortage has forced medical professionals to utilize marginal kidneys from expanded criteria donors (ECD) to broaden the donor pool and shorten wait times for patients with end-stage renal disease. However, recipients of ECD kidney grafts tend to have worse outcomes compared to those receiving organs from standard criteria donors (SCD), specifically increased risks of delayed graft function (DGF) and primary nonfunction incidence. Thus, representative methods for graft-quality assessment are strongly needed, especially for ECDs. Currently, graft-quality evaluation is limited to interpreting the donor’s recent laboratory tests, clinical risk scores, the visual evaluation of the organ, and, in some cases, a biopsy and perfusion parameters. The last few years have seen the emergence of many new technologies designed to examine organ function, including new imaging techniques, transcriptomics, genomics, proteomics, metabolomics, lipidomics, and new solutions in organ perfusion, which has enabled a deeper understanding of the complex mechanisms associated with ischemia-reperfusion injury (IRI), inflammatory process, and graft rejection. This review summarizes and assesses the strengths and weaknesses of current conventional diagnostic methods and a wide range of new potential strategies (from the last five years) with respect to donor graft-quality assessment, the identification of IRI, perfusion control, and the prediction of DGF.

Association of Admission, Nadir, and Terminal Donor Creatinine With Kidney Transplantation Outcomes

Introduction

When assessing deceased kidney donors, a key factor in organ acceptance and allocation is donor kidney function. It is unclear whether terminal, admission, or the highest of terminal and admission donor estimated glomerular filtration rate (eGFR) most predicts recipient outcomes.

Methods

We examined which measurement best predicts outcomes. Using data from the Australia and New Zealand Organ Donation and Dialysis and Transplant Registries, we included adult recipients of deceased donor kidney-only transplants over 2003 to 2019. We compared the 3 different exposure variables of admission, terminal, or highest eGFR. We created logistic regression models for delayed graft function (DGF), multilinear regression models for 6- and 12-month eGFR, and Cox proportional hazards models for graft loss, death censored graft failure and patient death.

Results

A total of 8971 transplant recipients were included. There was strong evidence of an association between terminal, admission, and highest donor eGFR and DGF and recipient eGFR at 6 and 12 months. The eGFR was a strong predictor of graft and death censored graft failure, but not patient death. Terminal was a better predictor than admission and highest eGFR particularly for more contemporaneous outcomes.

Conclusion

In assessing kidney donors, terminal eGFR were marginally better than admission and highest at predicting outcomes. Terminal eGFR should be used in risk equations to predict hard clinical endpoints.

Dynamic prediction models for graft failure in paediatric kidney transplantation

BACKGROUND

Several models have been proposed to predict kidney graft failure in adult recipients but none in younger recipients. Our objective was to propose a dynamic prediction model for graft failure in young kidney transplant recipients.

METHODS

We included 793 kidney transplant recipients waitlisted before the age of 18 years who received a first kidney transplantation before the age of 21 years in France in 2002-13 and survived >90 days with a functioning graft. We used a Cox model including baseline predictors only (sex, age at transplant, primary kidney disease, dialysis duration, donor type and age, human leucocyte antigen matching, cytomegalovirus serostatus, cold ischaemia time and delayed graft function) and two joint models also accounting for post-transplant estimated glomerular filtration rate (eGFR) trajectory. Predictive performances were evaluated using a cross-validated area under the curve (AUC) and R2 curves.

RESULTS

When predicting the risk of graft failure from any time within the first 7 years after paediatric kidney transplantation, the predictions for the following 3 or 5 years were accurate and much better with the joint models than with the Cox model (AUC ranged from 0.83 to 0.91 for the joint models versus 0.56 to 0.64 for the Cox model).

CONCLUSION

Accounting for post-transplant eGFR trajectory strongly increased the accuracy of graft failure prediction in young kidney transplant recipients.

A novel genomic model for predicting the likelihood of delayed graft function in DCD kidney transplantation

Background

The high incidence of delayed graft function (DGF) following kidney transplantation with donation after cardiac death allografts (DCD-KT) poses great challenges to transplant clinicians. This study aimed to explore the DGF-related biomarkers and establish a genomic model for DGF prediction specific to DCD KT.

Methods

By data mining a public dataset (GSE43974), the key DGF-related genes in DCD kidney biopsies taken after short-time reperfusion (45–60 min) were identified by differential expression analysis and a LASSO-penalized logistic regression model. Their coefficients for modeling were calculated by multivariate logistic regression. Receiver operating characteristic curves and a nomogram were generated to evaluate its predictive ability for DGF occurrence. Gene set enrichment analysis (GSEA) was performed to explore biological pathways underlying DGF in DCD KT.

Results

Five key DGF-related genes (CHST3, GOLPH3, ZBED5, AKR1C4, and ERRFI1) were first identified, all of which displayed good discrimination for DGF occurrence after DCD KT (all P<0.05). A five-mRNA-based risk score was further established and showed excellent predictive ability (AUC =0.9708, P<0.0001), which was obviously higher than that of the five genes alone. Eight DGF-related biological pathways in DCD kidneys, such as “arachidonic acid metabolism”, “lysosome”, “proximal tubule bicarbonate reclamation”, “glutathione metabolism”, were identified by GSEA (all P<0.05). Moreover, a convenient and visual nomogram based on the genomic risk score was also constructed and displayed high accuracy for DGF prediction specific to DCD KT.

Conclusions

The novel genomic model may effectively predict the likelihood of DGF immediately after DCD KT or even prior to transplantation in the context of normothermic machine perfusion in the future.

Development and external validation study combining existing models and recent data into an up-to-date prediction model for evaluating kidneys from older deceased donors for transplantation

With a rising demand for kidney transplantation, reliable pre-transplant assessment of organ quality becomes top priority. In clinical practice, physicians are regularly in doubt whether suboptimal kidney offers from older donors should be accepted. Here, we externally validate existing prediction models in a European population of older deceased donors, and subsequently developed and externally validated an adverse outcome prediction tool. Recipients of kidney grafts from deceased donors 50 years of age and older were included from the Netherlands Organ Transplant Registry (NOTR) and United States organ transplant registry from 2006-2018. The predicted adverse outcome was a composite of graft failure, death or chronic kidney disease stage 4 plus within one year after transplantation, modelled using logistic regression. Discrimination and calibration were assessed in internal, temporal and external validation. Seven existing models were validated with the same cohorts. The NOTR development cohort contained 2510 patients and 823 events. The temporal validation within NOTR had 837 patients and the external validation used 31987 patients in the United States organ transplant registry. Discrimination of our full adverse outcome model was moderate in external validation (C-statistic 0.63), though somewhat better than discrimination of the seven existing prediction models (average C-statistic 0.57). The model's calibration was highly accurate. Thus, since existing adverse outcome kidney graft survival models performed poorly in a population of older deceased donors, novel models were developed and externally validated, with maximum achievable performance in a population of older deceased kidney donors. These models could assist transplant clinicians in deciding whether to accept a kidney from an older donor.

Donor Plasma Mitochondrial DNA Is Correlated with Posttransplant Renal Allograft Function

BACKGROUND

The lack of accurate biomarkers makes it difficult to determine whether organs are suitable for transplantation. Mitochondrial DNA (mtDNA) correlates with tissue damage and kidney disease, making it a potential biomarker in organ evaluation.

METHODS

Donors who had experienced cardiac death and successfully donated their kidneys between January 2015 and May 2017 were included this study. We detected the level of mtDNA in the plasma of the donor using quantitative real-time polymerase chain reaction and then statistically analyzed the relationship between the level of mtDNA and the delayed graft function (DGF) of the recipient.

RESULTS

The incidence of DGF or slowed graft function (SGF) increased by 4 times (68% versus 16%, P < 0.001) when the donor mtDNA (dmtDNA) level was >0.114. When dmtDNA levels were >0.243, DGF and primary nonfunction were approximately 100% and 44%, respectively. Moreover, dmtDNA was an independent risk factor for slowed graft function and DGF. A prediction model for DGF based on dmtDNA achieved an area under the receiver operating characteristic curve for a prediction score as high as 0.930 (95% confidence interval 0.856-1.000), and the validation cohort results showed that the sensitivity and specificity of the model were 100% and 78%, respectively. dmtDNA levels were correlated with 6-month allograft function (R=0.332, P < 0.001) and 1-year graft survival (79% versus 99%, P < 0.001).

CONCLUSIONS

We conclusively demonstrated that plasma dmtDNA was an independent risk factor for DGF, which is valuable in organ evaluation. dmtDNA is a possible first predictive marker for primary nonfunction and worth further evaluation.

Is the Living Donor Kidney Profile Index Valuable in Japanese Patients?

INTRODUCTION

The Living Kidney Donor Profile Index (LKDPI) was recently proposed in the United States to evaluate living donor quality. Japan has a largely different renal transplant circumstance, such as a high ABO incompatibility rate. The aim of this study was to validate the LKDPI among the Japanese population and adjust the score.

METHODS

We performed a retrospective analysis of 133 living donors in renal transplant in our institution. We analyzed the clinical characteristics and outcomes, and created a modified LKDPI score considering the favorable ABO incompatible kidney transplant outcomes in Japan.

RESULTS

Median (interquartile range [IQR]) donor age was 59 (51 to 65) and median (IQR) body mass index was 22.9 kg/m² (20.9 to 25.2). ABO incompatibility rate was 28.5%. Median (IQR) donor estimated glomerular filtration rate (eGFR) (Chronic Kidney Disease Epidemiology Collaboration equation) was 108.7 mL/min/1.73 m² (99.9 to 115.5). The 1-year graft survival rate was 98.5%, and the 3-year graft survival rate was 97%. The incidence of antibody mediated rejection was 5.2%. The median (IQR) LKDPI score was 30.2 (11.8 to 46.8). This was significantly higher than the previously reported score in the United States, which was 12.8 (-0.8 to 27.2). The modified LKDPI (mLKDPI) score was 23.2 (4.1 to 35.1). LKDPI and mLKDPI did not show a diagnostic value in graft survival; however, LKDPI and mLKDPI showed significant diagnostic value in eGFR at 1 year (area under the curve [AUC]=0.627, P = .017; and AUC=0.673, P = .01).

CONCLUSION

Our outcomes had better survival even though with higher ABO incompatibility rate. According to original LKDPI, our donor pool is higher than the general US population. In this study, lower LKDPI tended to be associated with good allograft function, and mLKDPI has better diagnostic value than LKDPI. To compare internationally, an adjusted model for Japan might be necessary based on the outcomes of a large population.

Use of the Living Kidney Donor Profile Index in the Canadian Kidney Transplant Recipient Population: A Validation Study

Background:

The Living Kidney Donor Profile Index (LKDPI) was derived in a cohort of kidney transplant recipients (KTR) from the United States to predict the risk of total graft failure. There are important differences in patient demographics, listing practices, access to transplantation, delivery of care, and posttransplant mortality in Canada as compared with the United States, and the generalizability of the LKDPI in the Canadian context is unknown.

Objective:

The purpose of this study was to externally validate the LKDPI in a large contemporary cohort of Canadian KTR.

Design:

Retrospective cohort validation study.

Setting:

Toronto General Hospital, University Health Network, Toronto, Ontario, Canada

Patients:

A total of 645 adult (≥18 years old) living donor KTR between January 1, 2006 and December 31, 2016 with follow-up until December 31, 2017 were included in the study.

Measurements:

The predictive performance of the LKDPI was evaluated. The outcome of interest was total graft failure, defined as the need for chronic dialysis, retransplantation, or death with graft function.

Methods:

The Cox proportional hazards model was used to examine the relation between the LKDPI and total graft failure. The Cox proportional hazards model was also used for external validation and performance assessment of the model. Discrimination and calibration were used to assess model performance. Discrimination was assessed using Harrell’s C statistic and calibration was assessed graphically, comparing observed versus predicted probabilities of total graft failure.

Results:

A total of 645 living donor KTR were included in the study. The median LKDPI score was 13 (interquartile range [IQR] = 1.1, 29.9). Higher LKDPI scores were associated with an increased risk of total graft failure (hazard ratio = 1.01; 95% confidence interval [CI] = 1.0-1.02; P = .02). Discrimination was poor (C statistic = 0.55; 95% CI = 0.48-0.61). Calibration was as good at 1-year posttransplant but suboptimal at 3- and 5-years posttransplant.

Limitations:

Limitations include a relatively small sample size, predicted probabilities for assessment of calibration only available for scores of 0 to 100, and some missing data handled by imputation.

Conclusions:

In this external validation study, the predictive ability of the LKDPI was modest in a cohort of Canadian KTR. Validation of prediction models is an important step to assess performance in external populations. Potential recalibration of the LKDPI may be useful prior to clinical use in external cohorts.

Risk Indices in Deceased-donor Organ Allocation for Transplantation: Review From an Australian Perspective

Over the last decade, organ donation and transplantation rates have increased in Australia and worldwide. Donor and recipient characteristics for most organ types have generally broadened, resulting in the need to consider more complex data in transplant decision-making. As a result of some of these pressures, the Australian software used for donor and recipient data management is currently being updated. Because of the in-built capacity for improved data management, organ allocation processes will have the opportunity to be significantly reviewed, in particular the possible use of risk indices (RIs) to guide organ allocation and transplantation decisions. We aimed to review RIs used in organ allocation policies worldwide and to compare their use to current Australian protocols. Significant donor, recipient, and transplant variables in the indices were summarized. We conclude that Australia has the opportunity to incorporate greater use of RIs in its allocation policies and in transplant decision-making processes. However, while RIs can assist with organ allocation and help guide prognosis, they often have significant limitations which need to be properly appreciated when deciding how to best use them to guide clinical decisions.

Risk Factors for 1-Year Graft Loss After Kidney Transplantation: Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

With expansion of the pool of kidney grafts, through the use of higher-risk donors, and increased attention to donor management strategies, the 1-year graft survival rate is subject to change. It is, therefore, useful to elucidate 1-year graft survival rates by dissecting the characteristics of the low-risk and high-risk kidney transplant cases. The objective of our study was to evaluate factors purported to influence the risk of 1-year graft loss in kidney transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched bibliographic databases from 2000 to 2017 and included observational studies that measured the association between donor, recipient, the transplant operation, or early postoperative complications, and 1-year death-censored graft loss.

RESULTS

We identified 35 eligible primary studies, with 20 risk factors amenable to meta-analysis. Six factors were associated with graft loss, with moderate to high degree of certainty: donor age (hazard ratio [HR], 1.11 per 10-year increase; 95% confidence interval [95% CI], 1.04 to 1.18), extended criteria donors (HR, 1.35; 95% CI, 1.28 to 1.42), deceased donors (HR, 1.54; 95% CI, 1.32 to 1.82), number of HLA mismatches (HR, 1.08 per one mismatch increase; 95% CI, 1.07 to 1.09), recipient age (HR, 1.17 per 10-year increase; 95% CI, 1.09 to 1.25), and delayed graft function (HR, 1.89; 95% CI, 1.46 to 2.47) as risk factors for 1-year graft loss. Pooled analyses also excluded, with a high degree of certainty, any associations of cold ischemia time, recipient race, pretransplant body mass index, diabetes, and hypertension with 1-year graft loss.

CONCLUSIONS

Recipient age, donor age, standard versus extended criteria donor, living versus deceased donor, HLA mismatch, and delayed graft function all predicted 1-year graft survival. The effect of each risk factor is small.

Impact of adjusted kidney volume measured in the bench surgery on one-year renal function in kidney transplantation

BACKGROUND

Kidney transplantation is the treatment of choice in patient with end stage chronic kidney disease, offering the best long term survival and greater Quality of Life in this group of patients. Graft volume was correlated with improved renal function in living donor transplantations. The primary aim of this study was to correlate renal volume adjusted to body surface area with renal function one year (estimated glomerular filtration rate; eGFR) after kidney transplantation.

METHODS

This single-center, prospective cohort study included 256 patients who underwent kidney transplantation from January 2011 through December 2015 at Hospital das Clínicas de Botucatu-UNESP. We evaluated three kidney measurements during the bench surgery; the final graft volume was calculated using the ellipsoid formula and adjusted to body surface area.

RESULTS

In the living donors there was positive correlation between adjusted graft volume and eGFR (r = 0.311, p = 0.008). Multivariate analysis revealed that low rejection rate and increased adjusted graft volume were independent factors correlated with eGFR. In deceased donors, there was no correlation between adjusted kidney volume and eGFR (r = 0.08, p = 0.279) in univariate analysis, but a multivariate analysis indicated that lower kidney donor profile index (KDPI), absence of rejection and high adjusted kidney volume were independent factors for better eGFR.

CONCLUSION

Adjusted kidney volume was positively correlated with a satisfactory eGFR at one year after living donor and deceased donor transplantations.

A donor risk index for graft loss in pediatric living donor kidney transplantation

Pediatric kidney transplant candidates often have multiple potential living donors (LDs); no evidence-based tool exists to compare potential LDs, or to decide between marginal LDs and deceased donor (DD) kidney transplantation (KT). We developed a pediatric living kidney donor profile index (P-LKDPI) on the same scale as the DD KDPI by using Cox regression to model the risk of all-cause graft loss as a function of living donor characteristics and DD KDPI. HLA-B mismatch (adjusted hazard ratio [aHR] per mismatch = 1.04 1.271.55 ), HLA-DR mismatch (aHR per mismatch = 1.02 1.231.49 ), ABO incompatibility (aHR = 1.20 3.268.81 ), donor systolic blood pressure (aHR per 10 mm Hg = 1.01 1.071.18 ), and donor estimated GFR (eGFR; aHR per 10 mL/min/1.73 m2 = 0.88 0.940.99 ) were associated with graft loss after LDKT. Median (interquartile range [IQR]) P-LKDPI was -25 (-56 to 12). 68% of donors had P-LKDPI <0 (less risk than any DD kidney) and 25% of donors had P-LKDPI >14 (more risk than median DD kidney among pediatric KT recipients during the study period). Strata of LDKT recipients of kidneys with higher P-LKDPI had a higher cumulative incidence of graft loss (39% at 10 years for P-LDKPI ≥20, 28% for 20> P-LKDPI ≥-20, 23% for -20 > P-LKDPI ≥-60, 19% for P-LKDPI <-60 [log rank P < .001]). The P-LKDPI can aid in organ selection for pediatric KT recipients by allowing comparison of potential LD and DD kidneys.

Systematic Surgical Assessment of Deceased-Donor Kidneys as a Predictor of Short-Term Transplant Outcomes

BACKGROUND

Short-term kidney graft dysfunction is correlated with complications and it is associated with a decreased long-term survival; therefore, a scoring system to predict short-term renal transplant outcomes is warranted.

AIM

The aim of this study is to quantify the impression of the organ procurement surgeon in correlation with the following kidney transplant outcomes: immediate graft function (IGF), delayed graft function (DGF), and primary nonfunction (PNF). Results are compared to factors associated with the 1-year outcome.

METHODS

A regional prospective pilot study was performed using deceased-donor organ assessment forms to be filled out by procurement surgeons after procurement. Data were gathered on kidney temperature, perfusion, anatomy, atherosclerosis, and overall quality.

RESULTS

Included were 90 donors who donated 178 kidneys, 166 of which were transplanted. Variables that were significantly more prevalent in the DGF-or-PNF group (n = 65) are: large kidney size (length, p = 0.008; width, p = 0.036), poor perfusion quality (p = 0.037), lower diuresis (p = 0.039), fewer hypotensive episodes (p = 0.003), and donation-after-circulatory-death donors (p = 0.017). Multivariable analysis showed that perfusion quality and kidney width significantly predicted the short-term outcome. However multivariable analysis of long-term outcomes showed that the first measured donor creatinine, kidney donor risk index, IGF vs. DGF+PNG, and kidney length predicted outcomes.

CONCLUSIONS

Results show that short-term graft function and 1-year graft function indeed are influenced by different variables. DGF and PNF occur more frequently in kidneys with poor perfusion and in larger kidneys. A plausible explanation for this is that these kidneys might be insufficiently washed out, or even congested, which may predispose to DGF. These kidneys would probably benefit most from reconditioning strategies, such as machine perfusion. A scoring system including these variables might aid in decision-making towards allocation and potential reconditioning strategies.

Combined Ex Vivo Hypothermic and Normothermic Perfusion for Assessment of High-risk Deceased Donor Human Kidneys for Transplantation

Background

Despite careful clinical examination, procurement biopsy and assessment on hypothermic machine perfusion, a significant number of potentially useable deceased donor kidneys will be discarded because they are deemed unsuitable for transplantation. Ex vivo normothermic perfusion (EVNP) may be useful as a means to further assess high-risk kidneys to determine suitability for transplantation.

Methods

From June 2014 to October 2015, 7 kidneys (mean donor age, 54.3 years and Kidney Donor Profile Index, 79%) that were initially procured with the intention to transplant were discarded based on a combination of clinical findings, suboptimal biopsies, long cold ischemia time (CIT) and/or poor hypothermic perfusion parameters. They were subsequently placed on EVNP using oxygenated packed red blood cells and supplemental nutrition for a period of 3 hours. Continuous hemodynamic and functional parameters were assessed.

Results

After a mean CIT of 43.7 hours, all 7 kidneys appeared viable on EVNP with progressively increasing renal blood flow over the 3-hour period of perfusion. Five of the 7 kidneys had excellent macroscopic appearance, rapid increase in blood flow to 200 to 250 mL/min, urine output of 40 to 260 mL/h and increasing creatinine clearance.

Conclusions

Favorable perfusion characteristics and immediate function after a 3-hour course of EVNP suggests that high-risk kidneys subjected to long CIT may have been considered for transplantation. The combined use of ex vivo hypothermic and normothermic perfusion may be a useful strategy to more adequately assess and preserve high-risk kidneys deemed unsuitable for transplantation. A clinical trial will be necessary to validate the usefulness of this approach.

The combined use of ex vivo hypothermic and normothermic perfusion may be a useful strategy to more adequately assess and preserve high-risk kidneys deemed unsuitable for transplantation.

Non-standard criteria donors in pediatric kidney transplantation

KT remains the treatment of choice for ESRD in children. However, the demand for kidney transplants continues to outstrip supply, even in the pediatric scenario. We reviewed the applicability of nonSCDs for pediatric KT. There is a lack of studies analyzing this modality among pediatric donors and recipients, where most conclusions are based on predictions from adult data. Nevertheless, marginal donors might be a reasonable option in selected cases. For example, the use of older LDs is an acceptable option, with outcomes comparable to SCDs. Organs donated after cardiac death represent another possibility, albeit with logistic, ethical, and legal limitations in some countries. AKI donors also constitute an option in special situations, although there are no pediatric data on these transplants. Likewise, there are no data on the use of expanded criteria donors in pediatric patients, but this appears not to be a good option, considering the compromised long-term survival.

Assessment of Major Posttransplant Complications Risk Among Potential Recipients of Kidney Transplant in Saint-Louis, Senegal

INTRODUCTION

Recipients of kidney transplants are a very heterogeneous population and the risk of posttransplantation complications markedly varies according to the recipient's status. Scoring systems that predict survival outcome after kidney transplantation can help physicians improve risk stratification among recipients and make the best therapeutic decisions. This study aimed to assess the 1-year risk of major adverse events in potential recipients of kidney transplant at Saint-Louis University Hospital.

MATERIAL AND METHODS

We performed a cross-sectional study including 65 patients with end-stage renal disease who were treated in the hemodialysis unit at Saint-Louis University Hospital. Scoring was based on a simple clinical tool with 4 items (age, cardiopulmonary factors, functional status, and metabolic parameters) reported to predict risk of severe adverse events during the first posttransplant year.

RESULTS

The mean age of patients in years ± SD was 46.9 ± 23.5 and 53% were male. Median dialysis duration was 29.9 months and the main causes of kidney disease were hypertension and diabetes. A history of coronary artery disease was present in 22.3% of patients, and 33.5% had a high cardiovascular risk. According to the clinical score, 63.8% of potential recipients of kidney transplant presented a high risk of adverse events and 12.5% had a low risk of developing major complications during their first year posttransplantation.

CONCLUSIONS

This study shows that based on a simple pretransplant clinical assessment, two-thirds of our patients are at high risk for major adverse events during their first posttransplantation year. Such information could be invaluable during the counseling of donor and recipient couples.

Evaluation of donor kidneys prior to transplantation: an update of current and emerging methods

The lack of suitable kidney donor organs has led to rising numbers of patients with end stage renal disease waiting for kidney transplantation. Despite decades of clinical experience and research, no evaluation process that can reliably predict the outcome of an organ has yet been established. This review is an overview of current methods and emerging techniques in the field of donor kidney evaluation prior to transplantation. Established techniques like histological evaluation, clinical scores, and machine perfusion systems offer relatively reliable predictions of delayed graft function but are unable to consistently predict graft survival. Emerging techniques including molecular biomarkers, new imaging technologies, and normothermic machine perfusion offer innovative approaches toward a more global evaluation of an organ with better outcome prediction and possibly even identification of targets for therapeutic interventions prior to transplantation. These techniques should be studied in randomized controlled trials to determine whether they can be safely used in routine clinical practice to ultimately reduce the discard rate and improve graft outcomes.

Is the Kidney Donor Risk Index a Useful Tool in Non-US Patients?

Background:

Deceased donor kidney allocation in the United States is guided by the Kidney Donor Risk Index (KDRI). The generalizability of the KDRI beyond the United States has not been widely studied.

Objective:

To assess the generalizability of the KDRI in a cohort of non-US (Canadian) deceased donor kidney transplant recipients.

Design:

Population-based retrospective cohort study.

Setting:

Ontario, Canada.

Patients:

Recipients of deceased donor kidneys from January 1, 2005, to March 31, 2011.

Methods:

Using administrative data, we analyzed a cohort of deceased donor kidney recipients in Ontario, Canada. The Kaplan-Meier method and Cox proportional hazards models were used to assess the relationship between KDRI and the outcomes of graft loss and death. KDRI was modeled continuously and categorically. The ability of models with KDRI to predict recipient outcomes beyond donor age was also explored. Model discrimination was assessed using c-statistics, evaluated at 5 years of follow-up.

Results:

A total of 1299 consecutive deceased donor kidney transplant recipients were included. The median follow-up was 5.5 years. Mean donor age increased from 27 to 64 years across ascending KDRI quintiles. The adjusted relative hazards (95% confidence interval) for total graft loss from Q2 to Q5 (referent = Q1) were 1.27 (0.89-1.80), 1.58 (1.13-2.22), 1.43 (1.01-2.02), and 2.15 (1.54-2.99), respectively. Increased relative hazards across KDRI quintiles were also observed for death-censored graft loss, but not death with graft function. All-cause mortality was increased for the highest KDRI quintile only. In this cohort, a model with KDRI performed better than a model with donor age alone (P = .009).

Limitations:

Large health care databases may have precluded the complete capture of covariate data.

Conclusions:

In conclusion, the KDRI is generalizable to Canadian patients in Ontario and may help inform risk assessment beyond donor age. The performance of KDRI in other non-US settings, and the need for additional model refinement, warrants further study.

Early Graft Loss after Kidney Transplantation: Endothelial Dysfunction of Renal Microvasculature

Decision process about the acceptance of the deceased donor kidney for transplantation might be challenging. Although histological evaluation of pretransplant donor kidney biopsy provides reliable information regarding cortical necrosis, vascular thrombosis, extensive global glomerulosclerosis, and interstitial fibrosis/tubular atrophy, only electron microscopy enables thorough and reliable insights into microvasculature changes of kidney graft. The aim of the present paper is to briefly present two cases of early kidney graft loss. In one case, the donor was exposed to long-term extracorporeal membrane oxygenation (ECMO); in the other case, the donor experienced Takotsubo cardiomyopathy. In both cases, light microscopy of pretransplant biopsy found no pathology or significant discrepancy in morphology of kidney graft, while electron microscopy revealed severe endothelial dysfunction of renal microvasculature. Our results suggest that severe injury of renal microvasculature with relatively preserved tubular epithelium may be associated with some conditions of deceased kidney donors leading to early kidney graft nonfunction and loss. Further studies are needed to determine prognostic significance of severe ultrastructural microvasculature lesions and to evaluate disease states and conditions that could be associated with severe endothelial dysfunction of kidney graft.

Propensity score-based comparison of the graft failure risk between kidney transplant recipients of standard and expanded criteria donor grafts: Toward increasing the pool of marginal donors

From a prospective and multicentric French cohort, we proposed an external validation study for the expanded criteria donor (ECD), based on 4833 kidney recipients transplanted for the first time between 2000 and 2014. We estimated the subject-specific effect from a multivariable Cox model. We confirmed a 1.75-fold (95% confidence interval [CI] 1.53-2.00, P < .0001) increase in graft failure risk if a given patient received an ECD graft compared to a graft from a donor with standard criteria (standard criteria donor [SCD]). Complementarily, we estimated the population-average effect using propensity scores. We estimated a 1.34-fold (95% CI 1.09-1.64, P = .0049) increase in graft failure risk among ECD patients receiving an ECD graft compared to receiving a SCD graft. With a 10-year follow-up, it corresponded to a decrease of 8 months of the mean time to graft failure due to ECD transplantation (95% CI 2-14 months). The population-average relative risk due to ECD transplantation and the corresponding absolute effect seem finally not so high. Regarding the increase of quality of life in transplantation, our study constitutes an argument to extend the definition of marginality by considering more grafts at high risk and thereby enlarging the pool of kidney grafts.

Systematic review of kidney transplantation functional predictors

CONTEXT

Kidney transplantation from donors with expanded criteria has increased the pool of kidneys at the cost of a higher risk of short and long-term graft dysfunction. The main issue lies in determining which kidneys will offer acceptable function and survival compared with the risk represented by surgery and subsequent immunosuppression.

OBJECTIVE

The objective of our article is to review the current evidence on the tools for predicting the functionality of kidney transplantation from cadaveric donors with expanded criteria and determining the validity for their use in standard practice.

ACQUISITION OF EVIDENCE

We conducted a systematic literature review according to the PRISM criteria, through Medline (http://www.ncbi.nlm.nih.gov) and using the keywords (in isolation or in conjunction) "cadaveric renal transplantation; kidney graft function appraisal, graft function predictors". We selected prospective and retrospective series and review articles. A total of 375 articles were analysed, 39 of which were ultimately selected for review.

SUMMARY OF THE EVIDENCE

The predictors of functionality include the following: The donor risk indices; the calculation of the renal functional weight or the assessment of the nephronic mass; the measurement of vascular resistances during perfusion in hypothermia; the measurement of the donor's biomarkers in urine and in the perfusion liquid; the measurement of functional and reperfusion parameters in normothermia; and the measurement of morphological parameters (microscopic and macroscopic) of the target organ. In this article, we present an explanatory summary of each of these parameters, as well as their most recent evidence on this issue.

DISCUSSION

None of the reviewed parameters in isolation could reliably predict renal function and graft survival. There is a significant void in terms of the macroscopic assessment of kidney transplantation.

CONCLUSIONS

We need to continue developing predictors of renal functionality to accurately define the distribution of each currently available donor kidney.

Prediction of delayed graft function using different scoring algorithms: A single-center experience

AIM

To compare the performance of 3 published delayed graft function (DGF) calculators that compute the theoretical risk of DGF for each patient.

METHODS

This single-center, retrospective study included 247 consecutive kidney transplants from a deceased donor. These kidney transplantations were performed at our institution between January 2003 and December 2012. We compared the occurrence of observed DGF in our cohort with the predicted DGF according to three different published calculators. The accuracy of the calculators was evaluated by means of the c-index (receiver operating characteristic curve).

RESULTS

DGF occurred in 15.3% of the transplants under study. The c index of the Irish calculator provided an area under the curve (AUC) of 0.69 indicating an acceptable level of prediction, in contrast to the poor performance of the Jeldres nomogram (AUC = 0.54) and the Chapal nomogram (AUC = 0.51). With the Irish algorithm the predicted DGF risk and the observed DGF probabilities were close. The mean calculated DGF risk was significantly different between DGF-positive and DGF-negative subjects (P < 0.0001). However, at the level of the individual patient the calculated risk of DGF overlapped very widely with ranges from 10% to 51% for recipients with DGF and from 4% to 56% for those without DGF. The sensitivity, specificity and positive predictive value of a calculated DGF risk ≥ 30% with the Irish nomogram were 32%, 91% and 38%.

CONCLUSION

Predictive models for DGF after kidney transplantation are performant in the population in which they were derived, but less so in external validations.

[New scores in renal transplantation: How can we use them?]

In renal transplant medicine, several scores have been recently developed in order to help decision-making in clinical practice. The aim of this update is to focus on these new scores that allow to better estimate the quality of the renal transplant, to refine the allocation policy, to help registration of old recipients on the waiting list, or to evaluate the risk to develop end-stage renal failure after living donation.

Effect of Replacing Race With Apolipoprotein L1 Genotype in Calculation of Kidney Donor Risk Index

Renal allografts from deceased African American donors with two apolipoprotein L1 gene (APOL1) renal-risk variants fail sooner than kidneys from donors with fewer variants. The Kidney Donor Risk Index (KDRI) was developed to evaluate organ offers by predicting allograft longevity and includes African American race as a risk factor. Substituting APOL1 genotype for race may refine the KDRI. For 622 deceased African American kidney donors, we applied a 10-fold cross-validation approach to estimate contribution of APOL1 variants to a revised KDRI. Cross-validation was repeated 10 000 times to generate distribution of effect size associated with APOL1 genotype. Average effect size was used to derive the revised KDRI weighting. Mean current-KDRI score for all donors was 1.4930 versus mean revised-KDRI score 1.2518 for 529 donors with no or one variant and 1.8527 for 93 donors with two variants. Original and revised KDRIs had comparable survival prediction errors after transplantation, but the spread in Kidney Donor Profile Index based on presence or absence of two APOL1 variants was 37 percentage points. Replacing donor race with APOL1 genotype in KDRI better defines risk associated with kidneys transplanted from deceased African American donors, substantially improves KDRI score for 85-90% of kidneys offered, and enhances the link between donor quality and recipient need.

Strategies for an Expanded Use of Kidneys From Elderly Donors

The old-for-old allocation policy used for kidney transplantation (KT) has confirmed the survival benefit compared to remaining listed on dialysis. Shortage of standard donors has stimulated the development of strategies aimed to expand acceptance criteria, particularly of kidneys from elderly donors. We have systematically reviewed the literature on those different strategies. In addition to the review of outcomes of expanded criteria donor or advanced age kidneys, we assessed the value of the Kidney Donor Profile Index policy, preimplantation biopsy, dual KT, machine perfusion and special immunosuppressive protocols. Survival and functional outcomes achieved with expanded criteria donor, high Kidney Donor Profile Index or advanced age kidneys are poorer than those with standard ones. Outcomes using advanced age brain-dead or cardiac-dead donor kidneys are similar. Preimplantation biopsies and related scores have been useful to predict function, but their applicability to transplant or refuse a kidney graft has probably been overestimated. Machine perfusion techniques have decreased delayed graft function and could improve graft survival. Investing 2 kidneys in 1 recipient does not make sense when a single KT would be enough, particularly in elderly recipients. Tailored immunosuppression when transplanting an old kidney may be useful, but no formal trials are available.Old donors constitute an enormous source of useful kidneys, but their retrieval in many countries is infrequent. The assumption of limited but precious functional expectancy for an old kidney and substantial reduction of discard rates should be generalized to mitigate these limitations.

A Risk Index for Living Donor Kidney Transplantation

Choosing between multiple living kidney donors, or evaluating offers in kidney paired donation, can be challenging because no metric currently exists for living donor quality. Furthermore, some deceased donor (DD) kidneys can result in better outcomes than some living donor kidneys, yet there is no way to compare them on the same scale. To better inform clinical decision-making, we created a living kidney donor profile index (LKDPI) on the same scale as the DD KDPI, using Cox regression and adjusting for recipient characteristics. Donor age over 50 (hazard ratio [HR] per 10 years = 1.15 1.241.33 ), elevated BMI (HR per 10 units = 1.01 1.091.16 ), African-American race (HR = 1.15 1.251.37 ), cigarette use (HR = 1.09 1.161.23 ), as well as ABO incompatibility (HR = 1.03 1.271.58 ), HLA B (HR = 1.03 1.081.14 ) mismatches, and DR (HR = 1.04 1.091.15 ) mismatches were associated with greater risk of graft loss after living donor transplantation (all p < 0.05). Median (interquartile range) LKDPI score was 13 (1-27); 24.2% of donors had LKDPI < 0 (less risk than any DD kidney), and 4.4% of donors had LKDPI > 50 (more risk than the median DD kidney). The LKDPI is a useful tool for comparing living donor kidneys to each other and to deceased donor kidneys.

Decision Making by Young Transplant Surgeons Regarding Expanded-Criteria Donors With Acute Kidney Injury or Allocation Failure

BACKGROUND

The utilization of expanded-criteria donors (ECDs) has increased to overcome donor shortages. Unfortunately, the discard rate has also increased, especially in ECDs with acute kidney injury (AKI). We evaluated the outcomes of kidney transplantation in ECDs and standard-criteria donors (SCDs) with and without AKI.

METHODS

We reviewed the medical records of patients who underwent kidney transplantation. We used the AKI definition published by the Kidney Disease: Improving Global Outcomes group and reviewed the demographic characteristics of donors and recipients. We analyzed transplantation outcomes.

RESULTS

Twenty-seven patients underwent kidney transplantation from ECDs with AKI (n = 6) or without AKI (n = 5) and SCDs with AKI (n = 6) or without AKI (n = 10). Initial creatinine and estimated glomerular filtration rate (eGFR) were not significantly different between the groups. The incidence of delayed graft function was highest in ECDs with AKI (n = 3; 36.4%), but this was not a significantly difference. There was no difference in the last creatinine and eGFR in ECDs with AKI (1.32 mg/dL, 58.7 mL/min/1.73 m(2)), ECDs without AKI (1.67 mg/dL, 44.2 mL/min/1.73 m(2)), SCDs with AKI (0.94 mg/dL, 81.5 mL/min/1.73 m(2)) and SCDs without AKI (0.97 mg/dL, 81.8 mL/min/1.73 m(2)).

CONCLUSIONS

As the donor pool is extended to ECDs, young transplant surgeons may increasingly face decisions regarding ECDs with AKI or allocation failure. There is no consensus regarding discard criteria. However, if the donor showed initially normal creatinine levels or if dual-kidney transplantation can be performed, young transplant surgeons should not hesitate to use ECDs with AKI or allocation failure.

Dual Kidney Transplantation: Evaluation of Recipient Selection Criteria at Niguarda Hospital

BACKGROUND

Dual kidney transplantation (DKT) is a largely accepted strategy to enlarge the donor pool. Niguarda Hospital started this program in December 2010, and 38 DKT have been performed. In our series, we included recipients older than those in the other series published in literature. The aim of this study was to know if our recipient selection criteria for DKT are safe.

METHODS

We reviewed our data base of DKT and analyzed recipients' medical history, surgical technique, post-operative complications, graft survival, morbidity, and mortality. We then compared our results with the literature.

RESULTS

From December 2010 to April 2015, 38 DKT were performed in Niguarda Hospital. Delayed graft function was present in 21 recipients. Explantation of both kidneys was performed in 1 patient and explantation of 1 kidney in 6 patients. Post-operative complications were present in 8 patients. Five patients returned to hemodialysis after DKT. One recipient died of medical post-operative sepsis. The mean follow-up was 24 months. Graft survival and patient survival were 86.84% and 97.93%, respectively. Compared with the literature, our series had similar mortality and morbidity rates, even if recipients' age was higher than in other series.

CONCLUSIONS

The strategy of DKT allocation in elderly recipients is safe. Further studies have to be performed to optimized selection of the recipients for DKT not to disadvantage younger patients in the transplant waiting list and to improve the technique of organ evaluation and preservation to refine graft allocation.

Pre-transplant Evaluation of Donor Urinary Biomarkers can Predict Reduced Graft Function After Deceased Donor Kidney Transplantation

Several recipient biomarkers are reported to predict graft dysfunction, but these are not useful in decision making for the acceptance or allocation of deceased donor kidneys; thus, it is necessary to develop donor biomarkers predictive of graft dysfunction. To address this issue, we prospectively enrolled 94 deceased donors and their 109 recipients who underwent transplantation between 2010 and 2013 at 4 Korean transplantation centers. We investigated the predictive values of donor urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and L-type fatty acid binding protein (L-FABP) for reduced graft function (RGF). We also developed a prediction model of RGF using these donor biomarkers. RGF was defined as delayed or slow graft function. Multiple logistic regression analysis was used to generate a prediction model, which was internally validated using a bootstrapping method. Multiple linear regression analysis was used to assess the association of biomarkers with 1-year graft function. Notably, donor urinary NGAL levels were associated with donor AKI (P = 0.014), and donor urinary NGAL and L-FABP were predictive for RGF, with area under the receiver-operating characteristic curves (AUROC) of 0.758 and 0.704 for NGAL and L-FABP, respectively. The best-fit model including donor urinary NGAL, L-FABP, and serum creatinine conveyed a better predictive value for RGF than donor serum creatinine alone (P = 0.02). In addition, we generated a scoring method to predict RGF based on donor urinary NGAL, L-FABP, and serum creatinine levels. Diagnostic performance of the RGF prediction score (AUROC 0.808) was significantly better than that of the DGF calculator (AUROC 0.627) and the kidney donor profile index (AUROC 0.606). Donor urinary L-FABP levels were also predictive of 1-year graft function (P = 0.005). Collectively, these findings suggest donor urinary NGAL and L-FABP to be useful biomarkers for RGF, and support the use of a new scoring system based on donor biomarkers to facilitate decision-making in acceptance and allocation of deceased donor kidneys and contribute to maximal organ utilization.

A novel rodent model of severe renal ischemia reperfusion injury

Renal ischemia reperfusion injury (IRI) is a major problem, currently without treatments in clinical use. This reflects the failure of animal models to mimic the severity of IRI observed in clinical practice. Most described models lack both the ability to inflict a permanent reduction in renal function and the sensitivity to demonstrate the protective efficacy of different therapies in vivo. To test novel cell-based therapies, we have developed a model of renal IRI in Fisher 344 rats. Animals were subjected to 120 min of unilateral warm ischemia, during which they underwent an intra-renal artery infusion of therapeutic agents or vehicle. At either 2 or 6 weeks post-surgery, animals underwent terminal glomerular filtration rate (GFR) studies by inulin clearance to most accurately quantify renal function. Harvested kidneys underwent histological analysis. Compared to sham operations, saline treated animals suffered a long-term reduction in GFR of ≈50%. Histology revealed short- and long-term disruption of renal architecture. Despite the injury severity, post-operative animal losses are <5%. This model produces a severe, consistent renal injury that closely replicates the pathological processes encountered in clinical medicine. Renal artery infusion mimics the route likely employed in clinical transplantation, where the renal artery is accessible. Inulin clearance characterizes GFR, allowing full assessment of therapeutic intervention. This model is useful for screening therapeutic agents prior to testing in a transplant model. This reduces animal numbers needed to test drugs for clinical transplantation and allows for refinement of dosing schedules.