Half of kidney transplant candidates who are older than 60 years now placed on the waiting list will die before receiving a deceased-donor transplant

Medical Suitability and Willingness for Living Kidney Donation Among Older Adults

RATIONALE & OBJECTIVE

The benefits of kidney transplantation compared with treatment with dialysis, including in older adults, are primarily limited by the number of donated kidneys. We studied the potential to expand the use of older living kidney donors.

STUDY DESIGN

Secondary analysis of the Berlin Initiative Study, a population-based cohort.

SETTING & PARTICIPANTS

2,069 adults aged≥70 years in Germany.

EXPOSURE

Age and sex.

OUTCOME

Suitability for living donation assessed by the absence of kidney-related exclusions for donation including albuminuria and low estimated glomerular filtration rate (eGFR) as well as absence of other medical exclusions. Willingness for living and deceased kidney donation assessed by participant survey.

ANALYTICAL APPROACH

Descriptive analysis.

RESULTS

Among the 2,069 participants (median age 80 years, 53% women, median eGFR 63mL/min/1.73m2), 93% had≥1 medical contraindication for living donation at study entry unrelated to eGFR or albuminuria. Using 2 published eGFR and albuminuria thresholds for donor acceptance, 38% to 54% of participants had kidney-related exclusions for donation. Among the 5% to 6% of participants with neither medical nor kidney-related exclusions for living donation at baseline, 11% to 12% remained suitable for donation during 8 years of follow-up. Willingness for living or deceased donation was high (73% and 60%, respectively).

LIMITATIONS

GFR was not measured, and medical exclusions unrelated to eGFR and albuminuria were assessed using a cohort database complemented by claims data.

CONCLUSIONS

One in 20 older adults were potentially suitable for living kidney donation, and willingness for living donation was high. Further studies are warranted to define the feasibility of expanding living kidney donation among older adults.

PLAIN-LANGUAGE SUMMARY

Although potentially beneficial, kidney transplantation remains infrequent among older adults aged≥70 years with kidney failure. Study evaluated the potential to increase living kidney donation among older adults, including their medical suitability as well as willingness to donate. Among 2,069 community-dwelling older adults (median age 80 years), 5% to 6% had no exclusion to donation. Among these individuals, 11% to 12% remained suitable for donation during 8 years of follow-up. Most exclusions were not related to eGFR and albuminuria. Willingness to living donation was high (73%). These findings highlight the potential benefits from expanding the pool of transplantable kidneys through the use of living donation in older adults.

Experience of Older Adults and Their Family Members in the Kidney Transplant Evaluation

Importance

Transplant can be a valuable treatment option for older adults with kidney failure, and recent initiatives encourage more frequent referral to transplant centers. However, the evaluation process can be challenging, and most older adults do not ultimately receive a kidney.

Objective

To elucidate the perspectives and experiences of older adults with advanced kidney disease and their family members regarding the kidney transplant evaluation process.

Design, Setting, and Participants

This qualitative study, conducted between December 19, 2022, and February 5, 2024, included adults aged 65 years or older with advanced kidney disease (estimated glomerular filtration rate ≤20 mL/min/1.73 m2, receiving dialysis, or with a functioning kidney transplant) and their family members in Seattle, Washington.

Main Outcomes and Measures

Perspectives and experiences of patients and family members, identified through inductive thematic analysis of semi-structured interviews.

Results

A total of 26 older adults (16 [61.5%] men; median age, 68 years [range, 65-74 years]) with advanced kidney disease and 7 of their family members (4 [57.1%] women; median age, 65 years [range, 36-75 years]) were interviewed. Three dominant themes pertaining to the kidney transplant evaluation process were identified: (1) committed to transplant, (2) a complex and protracted process, and (3) responsibility without power. Because receiving a kidney was such an important priority, most participants were willing to engage in what could be a demanding process of testing and treatment narrowly focused on this future goal. However, the transplant evaluation could be lengthy, demanding, opaque, and fragmented, and patients often put other aspects of their lives on hold while awaiting an uncertain result. Patients and families often felt personally responsible for navigating and completing the transplant evaluation despite having little power to shape this process. Feeling responsible for the continued progress of a high-stakes evaluation process while remaining dependent on clinical teams and family members for support could strain relationships.

Conclusions and Relevance

This qualitative study found that older adults with advanced kidney disease and their family members were highly motivated to receive a kidney transplant but engagement in an evaluation process, over which they had little control, could have far-reaching implications for patients and families. These findings underline the importance of making the transplant evaluation process more transparent and person centered and of helping patients and families who are contemplating or engaged in the process to understand what to expect.

Machine learning validation of the AVAS classification compared to ultrasound mapping in a multicentre study

The Arteriovenous Access Stage (AVAS) classification simplifies information about suitability of vessels for vascular access (VA). It's been previously validated in a clinical study. Here, AVAS performance was tested against multiple ultrasound mapping measurements using machine learning. A prospective multicentre international study (NCT04796558) with patient recruitment from March 2021-July 2024. Demographics, risk factors, vessels parameters, types of predicted and created VA (pVA, cVA) were collected. We modelled pVA and cVA using the Random Forest algorithm. Model performance was estimated and compared using Bayesian generalized linear models. ROC AUC with 95% credible intervals was the performance metric. 1151 patients were included. ROC AUC for pVA prediction by AVAS was 0.79 (0.77;0.82) and by mapping was 0.85 (0.83;0.88). ROC AUC for cVA prediction by AVAS was 0.71 (0.69;0.74) and by mapping was 0.8 (0.78;0.83). Using AVAS with other parameters increased the ROC AUC to 0.87 for pVA (0.84;0.89) and 0.82 (0.79;0.84) for cVA. Using mapping with other parameters increased the ROC AUC to 0.88 for pVA (0.86;0.91) and 0.85 (0.83;0.88) for cVA. Multiple mapping measurements showed higher performance at VA prediction than AVAS. However, AVAS is simpler and quicker, so may be preferable for routine clinical practice.

Outcomes Using High KDPI Kidneys in Recipients Over 65 y of Age

Background

Kidney transplantation has been shown to improve life expectancy when compared with remaining on dialysis. However, there is an ever-expanding shortage of available organs for transplantation. The use of high kidney donor profile index (KDPI; >85) kidneys is 1 strategy to address this shortage. The current study aims to evaluate the advantage of accepting a high KDPI versus a low KDPI kidney (KDPI ≤85) in patients 65 y or older.

Methods

A single-center retrospective review of all patients, ages 65 y or older, who underwent deceased donor kidney transplantation between 2010 and 2020 was performed. Outcomes and wait times of recipients undergoing low KDPI (KDPI ≤85) versus high KDPI (KDPI >85) kidney transplantation were compared. Significance was defined as P < 0.05.

Results

Four hundred ninety-two patients were identified; 317 (64.4%) were men with a median age at transplantation of 69 y. Four hundred five patients received low KDPI kidneys, whereas the remaining received high KDPI grafts. High KDPI kidneys were procured from older donors (60 versus 47, P < 0.001) and had shorter cold ischemic time (25.0 versus 28.3 h, P = 0.01) compared with low KDPI kidneys. There was no significant difference in graft and patient survival between low and high KDPI recipients, with 85.1% and 86.2% grafts functioning at a follow-up of 4.85 (2.9-7.0) y, respectively. Pretransplant wait time was significantly shorter in the high KDPI group (2.7 [1.8-4.1] versus 3.5 [2.3-4.8] y; P = 0.004).

Conclusions

In patients 65 y or older undergoing deceased donor kidney transplantation, high KDPI kidneys may offer shorter pretransplant waiting times without compromising graft or patient survival.

Advancements in Tissue Engineering: A Review of Bioprinting Techniques, Scaffolds, and Bioinks

Tissue engineering is a multidisciplinary field that uses biomaterials to restore tissue function and assist with drug development. Over the last decade, the fabrication of three-dimensional (3D) multifunctional scaffolds has become commonplace in tissue engineering and regenerative medicine. Thanks to the development of 3D bioprinting technologies, these scaffolds more accurately recapitulate in vivo conditions and provide the support structure necessary for microenvironments conducive to cell growth and function. The purpose of this review is to provide a background on the leading 3D bioprinting methods and bioink selections for tissue engineering applications, with a specific focus on the growing field of developing multifunctional bioinks and possible future applications.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Competing Risks Analysis of Kidney Transplant Waitlist Outcomes: Two Important Statistical Perspectives

Modern competing risks analysis has 2 primary goals in clinical epidemiology as follows: (i) to maximize the clinician's knowledge of etiologic associations existing between potential predictor variables and various cause-specific outcomes via cause-specific hazard models, and (ii) to maximize the clinician's knowledge of noteworthy differences existing in cause-specific patient risk via cause-specific subdistribution hazard models (cumulative incidence functions [CIFs]). A perfect application exists in analyzing the following 4 distinct outcomes after listing for a deceased donor kidney transplant (DDKT): (i) receiving a DDKT, (ii) receiving a living donor kidney transplant (LDKT), (iii) waitlist removal due to patient mortality or a deteriorating medical condition, and (iv) waitlist removal due to other reasons. It is important to realize that obtaining a complete understanding of subdistribution hazard ratios (HRs) is simply not possible without first having knowledge of the multivariable relationships existing between the potential predictor variables and the cause-specific hazards (perspective #1), because the cause-specific hazards form the "building blocks" of CIFs. In addition, though we believe that a worthy and practical alternative to estimating the median waiting-time-to DDKT is to ask, "what is the conditional probability of the patient receiving a DDKT, given that he or she would not previously experience one of the competing events (known as the cause-specific conditional failure probability)," only an appropriate estimator of this conditional type of cumulative incidence should be used (perspective #2). One suggested estimator, the well-known "one minus Kaplan-Meier" approach (censoring competing events), simply does not represent any probability in the presence of competing risks and will almost always produce biased estimates (thus, it should never be used).

Quantifying the Effect of Consent for High-Kidney Donor Profile Index Deceased Donor Transplants in the United States

Key Points

Nationally, 41% of kidney transplant candidates consented to receive high–Kidney Donor Profile Index (KDPI) donor offers in the United States. There was wide variation in consent proportion for high-KDPI donors on the basis of individual characteristics and transplant centers. Consent for high-KDPI kidneys was associated with 15% higher adjusted rates of deceased donor transplantation.

Background

Despite known benefits of kidney transplantation, including transplantation from donors with increased risk factors, many waitlisted candidates die before transplantation. Consent to receive donor kidneys with lower expected survival (e.g ., Kidney Donor Profile Index [KDPI] >85%) is typically obtained at waitlist placement. The presumed benefit of consent to receive high-KDPI donor kidneys is higher likelihood and timeliness of donor offers for transplantation. However, the specific effect of consent on access to transplantation is unclear. Our aims were to evaluate the characteristics of candidates consenting to high-KDPI donor kidneys and the likelihood of receiving a deceased donor transplant over time on the basis of consent.

Methods

We used national Scientific Registry of Transplant Recipients data between 2015 and 2022 (n =213,364). We evaluated the likelihood of consent using multivariable logistic models and time to deceased donor transplant with cumulative incidence plots accounting for competing risks and multivariable Cox models.

Results

Overall, high-KDPI consent was 41%, which was higher among candidates who were older, were Black or Hispanic, had higher body mass index, had diabetes, had vascular disease, and had 12–48 months prelisting dialysis time, with significant center-level variation. High-KDPI consent was associated with higher rates of deceased donor transplant (adjusted hazard ratio=1.15; 95% confidence interval, 1.13 to 1.17) with no difference in likelihood of deceased donor transplant from donors with KDPI <85%. The effect of high-KDPI consent on higher rates of deceased donor transplantation was higher among candidates older than 60 years and candidates with diabetes and variable on the basis of center characteristics.

Conclusions

There is significant variation of consent for high-KDPI donor kidneys and higher likelihood of transplantation associated with consent.

The Kidney Not Taken: Single-Kidney Use in Deceased Donors

BACKGROUND

The nonuse rate for kidneys recovered from deceased donors is increasing, rising to 27% in 2023. In 10% of these cases, 1 kidney is transplanted but the mate kidney is not.

STUDY DESIGN

We conducted a retrospective, single-center cohort study from December 2001 to May 2023 comparing single kidneys transplanted at our center (where the contralateral kidney was not used) to kidneys where both were transplanted separately, at least 1 of which was at our center.

RESULTS

We performed 395 single deceased-donor kidney transplants in which the mate kidney was not transplanted. Primary reasons for mate kidney nonuse were as follows: no recipient located or list exhausted (33.4%), kidney trauma or injury or anatomic abnormalities (18.7%), biopsy findings (16.7%), and poor renal function (13.7%). Mean donor and recipient ages were 51.5 ± 14.2 and 60 ± 12.6 years, respectively. Mean kidney donor profile index was 73% ± 22%, and 104 donors (26.3%) had kidney donor profile index >85%. Mean cold ischemia was 25.6 ± 7.4 hours, and 280 kidneys (70.7%) were imported. Compared with 2,303 concurrent control transplants performed at our center, primary nonfunction or thrombosis (5.1% single vs 2.8% control) and delayed graft function (35.4% single vs 30.1% control) were greater with single-kidney use (both p < 0.05). Median patient and death-censored graft survival were shorter in the single group (11.6 vs 13.5 years, p = 0.03 and 11.6 vs 19 years, p = 0.003), although the former was at least double median survival on the waiting list. In patients with functioning grafts in the single-kidney group, 1-year mean serum creatinine was 1.77 ± 0.8 mg/dL and estimated glomerular filtration rate was 44.8 ± 20 mL/min/1.73 m 2 .

CONCLUSIONS

These findings suggest that many mate kidneys are being inappropriately rejected, given the acceptable outcomes that can be achieved by transplanting the single kidney in appropriately selected recipients.

Barriers and Facilitators to Exercise in Older Adults Awaiting Kidney Transplantation and Their Care Partners

Rationale & Objective

Despite guidelines calling to improve physical activity in older adults, and evidence suggesting that prekidney transplant physical function is highly associated with posttransplant outcomes, only a small percentage of older patients treated with dialysis are engaged in structured exercise. We sought to elucidate barriers and facilitators of exercise among older adults treated with dialysis awaiting transplant and their care partners.

Study Design

Individual, in-depth, cognitive interviews were conducted separately for patients and care partners through secure web-conferencing.

Setting & Participants

Twenty-three patients (≥50 years of age, treated with dialysis from the University of San Francisco kidney transplantation clinic, with a short physical performance battery of ≤10) and their care partners.

Analytical Approach

All audio interviews were transcribed verbatim. Three investigators independently coded data and performed qualitative thematic content. The interview guide was updated iteratively based on the Capability Opportunity Motivation Behavior model.

Results

Patients' median age was 60 years (57 ± 63.5) and care partners' median ages was 57 years (49.5 ± 65.5). Thirty-nine percent of patients and 78% of care partners were female, 39% of patients and 30% of care partners self-identified as African American, and 47% of dyads were spouse or partner relationships. Major themes for barriers to pretransplant exercise included lack of understanding of an appropriate regimen, physical impairments, dialysis schedules, and safety concerns. Major facilitators included having individualized or structured exercise programs, increasing social support for patients and care partners, and motivation to regain independence or functionality or to promote successful transplantation.

Limitations

Participants geographically limited to Northern California.

Conclusions

Although patients and care partners report numerous barriers to pretransplant exercise and activity, they also reported many facilitators. An individualized, structured, home-based exercise program could circumvent many of the reported barriers and allow older patients to improve pretransplant physical function.

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.

Factors Underlying Racial Disparity in Utilization of Hepatitis C-Viremic Kidneys in the United States

Utilization of hepatitis C (HCV) viremic kidneys is increasing in the United States. We examined racial disparity in this utilization using UNOS/OPTN data (2014-2020) and mixed effects models adjusting for donor/recipient/center factors. Included in the study were 58,786 adults receiving a deceased donor kidney transplant from 191 centers. Two thousand six hundred thirteen (4%) received kidneys from HCV-viremic donors. Of these, 1598 (61%) were HCV seronegative and 1015 (49%) were HCV seropositive. Among seronegative recipients, before adjusting for waiting time and education, Blacks (OR 0.69, 95%CI (0.60, 0.80)), Hispanics (OR 0.63, 95%CI (0.51, 0.79)), and Asians (OR 0.69, 95%CI (0.53, 0.90)) were less likely than Whites to receive HCV-viremic kidneys. In final models, effect of race was attenuated. Notably, shorter waiting time (OR 0.65, 95%CI (0.63, 0.67)) and increasing educational level (grade school less likely compared to high school OR 0.67, 95% CI (0.49, 0.92) and college more likely than high school (OR 1.16 95% CI (1.02, 1.31)) were associated with receipt of HCV-viremic kidneys. Among HCV-seropositive recipients, recipient race was not independently associated with receipt of HCV-viremic kidneys; however, centers with larger populations of Black waitlisted patients were more likely to utilize HCV-viremic kidneys (OR 1.71, 95%CI (1.20, 2.45)) compared to other centers. Our results suggest recipient race does not independently determine who receives HCV-viremic kidneys; however, other underlying factors including waiting time, education (among seronegative), and center racial mix (among seropositive) contribute to the current differential distribution of HCV-viremic kidneys among races.

Single center experience and literature review of kidney transplantation from non-ideal donors with acute kidney injury: Risk and reward

INTRODUCTION

There is limited experience transplanting kidneys from either expanded criteria donors (ECD) or donation after circulatory death (DCD) deceased donors with terminal acute kidney injury (AKI).

METHODS

AKI kidneys were defined by a donor terminal serum creatinine level >2.0 mg/dL whereas non-ideal deceased donor (NIDD) kidneys were defined as AKI/DCD or AKI/ECDs.

RESULTS

From February 2007 to March 2023, we transplanted 266 single AKI donor kidneys including 29 from ECDs, 29 from DCDs (n = 58 NIDDs), and 208 from brain-dead standard criteria donors (SCDs). Mean donor age (43.7 NIDD vs. 33.5 years SCD), KDPI (66% NIDD vs. 45% SCD), and recipient age (57 NIDD vs. 51 years SCD) were higher in the NIDD group (all p < .01). Mean waiting times (17.8 NIDD vs. 24.2 months SCD) and dialysis duration (34 NIDD vs. 47 months SCD) were shorter in the NIDD group (p < .05). Delayed graft function (DGF, 48%) and 1-year graft survival (92.7% NIDD vs. 95.9% SCD) was similar in both groups. Five-year patient and kidney graft survival rates were 82.1% versus 89.9% and 82.1% versus 75.2% (both p = NS) in the NIDD versus SCD groups, respectively.

CONCLUSIONS

The use of kidneys from AKI donors can be safely liberalized to include selected ECD and DCD donors.

The experiences of patients with peritoneal dialysis: A systematic review of qualitative evidence protocol

BACKGROUND

The incidence of end-stage renal disease (ESRD) is on the rise, it has been a major public health problem and places a significant burden on healthcare systems. Peritoneal dialysis (PD) is an increasingly popular form of renal replacement therapy. Patients undergoing dialysis treatment undergo specific pathophysiological and psychological changes. The aim of this systematic review is to investigate the experiences of ESRD patients receiving PD in order to gain deeper insights into their attitudes and beliefs towards this treatment. This will help researchers and health professionals to target interventions to improve the quality of life of PD patients.

DESIGN

Protocol for a qualitative systematic review.

METHODS

This systematic review protocol will follow the Joanna Briggs Institute (JBI) meta-analysis methodology. We will conduct a comprehensive search, including English and Chinese databases. It will include all published qualitative studies of patients' experiences with PD. Both English and Chinese literature will be covered. Two reviewers will independently participate in the literature selection, document selection, and data extraction process. Synthesis will be carried out through in-depth reading of the original text and subsequent creation of similar categories.

RESULTS

Experiencing is a complex dimension that includes physical, psychological and social aspects. This review will enable nurses to gain a deeper understanding of the feelings and beliefs of patients with PD. Our findings will provide healthcare professionals and policy makers with evidence to provide better care for patients with PD.

Physiological Age by Artificial Intelligence-Enhanced Electrocardiograms as a Novel Risk Factor of Mortality in Kidney Transplant Candidates

BACKGROUND

Mortality risk assessment before kidney transplantation (KT) is imperfect. An emerging risk factor for death in nontransplant populations is physiological age as determined by the application of artificial intelligence to the electrocardiogram (ECG). The aim of this study was to examine the relationship between ECG age and KT waitlist mortality.

METHODS

We applied a previously developed convolutional neural network to the ECGs of KT candidates evaluated 2014 to 2019 to determine ECG age. We used a Cox proportional hazard model to examine whether ECG age was associated with waitlist mortality.

RESULTS

Of the 2183 patients evaluated, 59.1% were male, 81.4% were white, and 11.4% died during follow-up. Mean ECG age was 59.0 ± 12.0 y and mean chronological age at ECG was 53.3 ± 13.6 y. After adjusting for chronological age, comorbidities, and other characteristics associated with mortality, each increase in ECG age of >10 y than the average ECG age for patients of a similar chronological age was associated with an increase in mortality risk (hazard ratio 3.59 per 10-y increase; 95% confidence interval, 2.06-5.72; P  < 0.0001).

CONCLUSIONS

ECG age is a risk factor for KT waitlist mortality. Determining ECG age through artificial intelligence may help guide risk-benefit assessment when evaluating candidates for KT.

Kidney transplant in the next decade: Strategies, challenges and vision of the future

Although the results of kidney transplantation (KT) have improved substantially in recent years, a chronic and inexorable loss of grafts mainly due to the death of the patient and chronic dysfunction of the KT, continues to be observed. The objectives, thus, to optimize this situation in the next decade are fundamentally focused on minimizing the rate of kidney graft loss, improving patient survival, increasing the rate of organ procurement and its distribution, promoting research and training in health professionals and the development of scientific registries providing clinical and reliable information that allow us to optimize our clinical practice in the field of KT. With this perspective, this review will deep into: (1) strategies to avoid chronic dysfunction and graft loss in the medium and long term; (2) to prolong patient survival; (3) strategies to increase the donation, maintenance and allocation of organs; (4) promote clinical and basic research and training activity in KT; and (5) the analysis of the results in KT by optimizing and merging scientific registries.

Long-term outcomes of kidney transplantation from deceased donors with terminal acute kidney injury: Single center experience and literature review

INTRODUCTION

Long-term outcomes of kidney transplantation from deceased donors (DDKTs) with terminal acute kidney injury (AKI) are not well defined.

METHODS

Single center retrospective review of DDKTs from 1/31/07-12/31/19. AKI kidneys were defined by a doubling of the donor's admission serum creatinine (SCr) level AND a terminal SCr ≥2.0 mg/dl.

RESULTS

A total of 188 AKI DDKTs were performed, including 154 from brain-dead standard criteria donors (SCD). Mean donor age was 36 years and mean Kidney Donor Profile Index was 50%; mean admission and terminal SCr levels were 1.3 and 3.1 mg/dl, respectively. With a mean follow-up of 94 months (median 89 months), overall patient (both 71.3%) and graft survival (54% AKI vs. 57% non-AKI) rates were comparable to concurrent DDKTs from brain-dead non-AKI SCDs (n = 769). Delayed graft function (DGF) was higher in AKI kidney recipients (47% vs. 20% non-AKI DDKTs, p < .0001). DGF was associated with lower graft survival in recipients of both AKI and non-AKI SCD kidneys but the impact was earlier and more pronounced in non-AKI recipients.

CONCLUSIONS

Despite having more than twice the incidence of DGF, kidneys from deceased donors with terminal AKI have long-term outcomes comparable to non-AKI SCD kidneys and represent a safe and effective method to expand the donor pool.

Kidney Transplantation in an Elderly Veteran Population With Hepatitis C Virus Nucleic Acid Test-Positive Donors Results in Improved Outcomes After Prophylactic Glecaprevir/Pibrentasvir Therapy

BACKGROUND

The average age of waitlisted veterans is 64. Recent data has shown the safety and benefits of using kidneys from hepatitis C virus nucleic acid test (HCV NAT)-positive donors. However, these studies were limited to younger patients with initiation of therapy after transplant. The aim of this study was to determine the safety and efficacy of a preemptive treatment protocol in an elderly veteran population.

METHODS

This was a prospective, open-label trial with 21 deceased donor kidney transplantations (DDKTs) with HCV NAT-positive kidneys and 32 DDKTs with HCV NAT-negative transplanted between November 2020 and March 2022. The HCV NAT-positive recipients were treated with once-daily glecaprevir/pibrentasvir started preoperatively and continued for 8 weeks. Sustained virologic response (SVR)12 was determined by negative NAT Student's t test. Other endpoints included patient and graft survival as well as graft function.

RESULTS

There was no major difference between the cohorts other than the increased number of donation after circulatory death kidneys in the non-HCV recipients. Post-transplant graft and patient outcomes were equivalent between the groups. Eight of the 21 HCV NAT-positive recipients had detectable HCV viral loads 1 day after transplant, but all were undetectable by day 7 with 100% SVR12. Calculated estimated glomerular filtration rate was improved in the HCV NAT-positive cohort at week 8 (58.26 vs 47.16 mL/min; P < .05) and continued to be improved over non-HCV recipients 1 year after transplant (71.38 vs 42.15 mL/min; P < .05). Immunologic risk stratification was similar in both cohorts.

CONCLUSION

The HCV NAT-positive transplants with a preemptive treatment protocol results in improved graft function with minimal to no complications in an elderly veteran population.

The role of Advanced Practice Nurses in creating the Kidney Transplant candidate care map (APN-preKT): a convergent-parallel mixed methods research protocol

BACKGROUND

Waiting time for kidney transplants (KT) is an important health determinant for patients with chronic kidney disease (CKD). During this time, ongoing evaluation and participation is necessary in order to guarantee the quality and suitability of the proposed treatment. There is no existing literature on the potential impact of inclusion of an Advanced Practice Nurse (APN) role in the hospital setting on care for CKD patients who are candidates for KT. The main objectives of this protocol are: to analyse outpatient nursing activity in the care of individuals with KT in Spain; to identify the needs of individuals who are KT candidates; and to measure the impact of the APN role through patient outcomes and experiences. These objectives are fulfilled through 5 specific related substudies.

METHODS

A convergent parallel mixed methods approach will be conducted between July 2021 and April 2024. Quantitative and qualitative data will be collected and analysed separately to ascertain whether the findings confirm or contradict one another. Each of the 5 substudies of the project require a specific design, sampling method, and data collection procedure in order to meet the overall objectives for the project.

DISCUSSION

The results of the project are expected to inform the design of future nursing roles and contribute to future improvements in the quality of care provided. The data that may be obtained from this protocol are limited to the specific context of the study facility and may be extrapolated but not compared to other settings due to the variability of care pathways for KT candidates internationally.

TRIAL REGISTRATION

This project was approved by the Clinical Research Ethics Committee (no.2020/9418/I). The study was supported by the "Strategic Plan for Health Research and Innovation" from the Generalitat de Catalunya, registration number SLT017/20/000001, with a contribution of 57,239 euros.

Does anybody really know what (the kidney median waiting) time is?

The median waiting time (MWT) to deceased donor kidney transplant is of interest to patients, clinicians, and the media but remains elusive due to both methodological and philosophical challenges. We used Organ Procurement and Transplantation Network data from January 2003 to March 2022 to estimate MWTs using various methods and timescales, applied overall, by era, and by candidate demographics. After rising for a decade, the overall MWT fell to 5.19 years between 2015 and 2018 and declined again to 4.05 years (April 2021 to March 2022), based on the Kaplan-Meier method applied to period-prevalent cohorts. MWTs differed markedly by blood type, donor service area, and pediatric vs adult status, but to a lesser degree by race/ethnicity. Choice of methodology affected the magnitude of these differences. Instead of waiting years for an answer, reliable kidney MWT estimates can be obtained shortly after a policy is implemented using the period-prevalent Kaplan-Meier approach, a theoretical but useful construct for which we found no evidence of bias compared with using incident cohorts. We recommend this method be used complementary to the competing risks approach, under which MWT is often inestimable, to fill the present information void concerning the seemingly simple question of how long it takes to get a kidney transplant in the United States.

Kidney Transplant Outcomes in Recipients Over the Age of 70

BACKGROUND

Patients older than 70 years are the fastest-growing age group of patients requiring renal replacement therapy. This has resulted in a corresponding increase in the number of elderly transplant recipients. We hypothesized that graft survival in this population would be comparable to that seen in the literature on kidney transplant recipients under 70 years of age.

METHODS

This was a retrospective, single-center review of outcomes of kidney transplant recipients aged ≥70 years. Patients were dichotomized based on whether their allograft originated from a living or deceased donor.

RESULTS

A total of 59 recipients aged ≥70 years underwent kidney transplantation. Of these, five (8.5%) were lost to follow-up within the first year post transplant and excluded from the analysis. History of cerebrovascular accident (p = 0.003), coronary artery disease (p = 0.03), postoperative return to the operating room (p = 0.03), and readmission within one year of transplant were predictive of graft loss (p = 0.003). Overall graft survival in our cohort declined from 92.6% at one year to 53.8% at five years. Death-censored graft survival was 100% at one year and decreased to 80.8% at five years. There were no differences seen in patient, graft, or death-censored graft survival based on donor type.

CONCLUSIONS

Kidney transplant patients over 70 years, as seen in our cohort, had good short-term outcomes. Graft survival is similar to rates seen in younger cohorts but the decline in this rate over time is steeper in the older age group, possibly due to decreased patient survival. These findings could be validated further in larger multi-center studies.

Short-term outcomes after transplantation of deceased donor kidneys with acute kidney injury: a retrospective analysis of a multicenter cohort of marginal donor kidneys with post-explantation biopsies

BACKGROUND

Deceased donor kidneys with acute kidney injury (AKI) are often discarded because of concerns about inferior transplant outcomes. A means of grading the quality of such kidneys is the performance of procurement biopsies.

METHODS

This is a retrospective study of 221 brain death donors with marginal kidneys transplanted in 223 recipients in Germany. Marginal kidneys were defined as kidneys with procurement biopsies done exceptionally to assess suitability for transplantation in otherwise potentially discarded organs. The impact of deceased donor AKI on patient survival and death-censored graft survival at 1, 3 and 5 years and graft function at 1 and 3 years after transplantation was investigated.

RESULTS

Recipients of kidneys with stage 3 AKI had a greater incidence of delayed graft function [DGF; ORStage 1: 1.435 (95% CI 0.438-0.702), ORStage 2: 2.463 (95% CI 0.656-9.245), ORStage 3: 4.784 (95% CI 1.421-16.101)] but a similar graft and patient survival compared to recipients of donors without AKI and with AKI stage 1 and 2 as well. The coexistence of recipient DGF and donor AKI was associated with the lowest graft survival and function rates.

CONCLUSION

The transplantation of deceased donor marginal kidneys with AKI confers a higher risk for DGF but is associated with acceptable graft and patient outcomes, which do not differ in comparison with marginal donor kidneys without AKI. Graft prognosis is especially poor if donor AKI and recipient DGF concur. Donor AKI was a risk factor independent of the histological lesions of procurement biopsies.

Kidney utility and futility

Changes in kidney allocation coupled with the COVID-19 pandemic have placed tremendous strain on current systems of organ distribution and logistics. Although the number of deceased donors continues to rise annually in the United States, the proportion of marginal deceased donors (MDDs) is disproportionately growing. Cold ischemia times and kidney discard rates are rising in part related to inadequate planning, resources, and shortages. Complexity in kidney allocation and distribution has contributed to this dilemma. Logistical issues and the ability to reperfuse the kidney within acceptable time constraints increasingly determine clinical decision-making for organ acceptance. We have a good understanding of the phenotype of "hard to place" MDD kidneys, yet continue to promote a "one size fits all" approach to organ allocation. Allocation and transportation systems need to be agile, mobile, and flexible in order to accommodate the expanding numbers of MDD organs. By identifying "hard to place" MDD kidneys early and implementing a "fast-track" or open offer policy to expedite placement, the utilization rate of MDDs would improve dramatically. Organ allocation and distribution based on location, motivation, and innovation must lead the way. In the absence of change, we are sacrificing utility for futility and discard rates will continue to escalate.

Risk factors for graft loss and death among kidney transplant recipients: A competing risk analysis

INTRODUCTION

Kidney transplantation is the best therapeutical option for CKD patients. Graft loss risk factors are usually estimated with the cox method. Competing risk analysis could be useful to determine the impact of different events affecting graft survival, the occurrence of an outcome of interest can be precluded by another. We aimed to determine the risk factors for graft loss in the presence of mortality as a competing event.

METHODS

A retrospective cohort of 1454 kidney transplant recipients who were transplanted between July 1, 2008, to May 31, 2019, in Colombiana de Trasplantes, were analyzed to determine risk factors of graft loss and mortality at 5 years post-transplantation. Kidney and patient survival probabilities were estimated by the competing risk analysis. The Fine and Gray method was used to fit a multivariable model for each outcome. Three variable selection methods were compared, and the bootstrapping technique was used for internal validation as split method for resample. The performance of the final model was assessed calculating the prediction error, brier score, c-index and calibration plot.

RESULTS

Graft loss occurred in 169 patients (11.6%) and death in 137 (9.4%). Cumulative incidence for graft loss and death was 15.8% and 13.8% respectively. In a multivariable analysis, we found that BKV nephropathy, serum creatinine and increased number of renal biopsies were significant risk factors for graft loss. On the other hand, recipient age, acute cellular rejection, CMV disease were risk factors for death, and recipients with living donor had better survival compared to deceased-donor transplant and coronary stent. The c-index were 0.6 and 0.72 for graft loss and death model respectively.

CONCLUSION

We developed two prediction models for graft loss and death 5 years post-transplantation by a unique transplant program in Colombia. Using a competing risk multivariable analysis, we were able to identify 3 significant risk factors for graft loss and 5 significant risk factors for death. This contributes to have a better understanding of risk factors for graft loss in a Latin-American population. The predictive performance of the models was mild.

A tool for decision-making in kidney transplant candidates with poor prognosis to receive deceased donor transplantation in the United States

The primary outcomes for kidney transplant candidates are receipt of deceased or living donor transplant, death or removal from the waiting list. Here, we conducted a retrospective analysis of national Scientific Registry of Transplant Recipients data to evaluate outcomes for 208,717 adult kidney transplant candidates following the 2014 Kidney Allocation System in the United States. Competing risks models were utilized to evaluate Time to Equivalent Risk (TiTER) of deceased donor transplantation (DDTX) and death versus waitlist removal. We also evaluated TiTER based on kidney donor profile index (KDPI) and donor age. For all groups, the cumulative incidence of DDTX was initially higher from time of listing than death or waitlist removal. However, following accrued time on the waiting list, the cumulative incidence of death or waitlist removal exceeded DDTX for certain patient groups, particularly older, diabetic, blood type B and O and shorter pre-listing dialysis time. TiTER for all candidates aged 65-69 averaged 41 months and for 70 and older patients 28 months. Overall, 39.6% of candidates were in risk groups with TiTER under 72 months and 18.5% in groups with TiTER under 24 months. Particularly for older candidates, TiTER for kidneys was substantially shorter for younger donors or lower KDPI. Thus, our findings reveal that a large proportion of waitlisted patients in the United States have poor prognoses to ever undergo DDTX and our data may improve shared decision-making for candidates at time of waitlist placement. Hence, for specific patient groups, TiTER may be a useful tool to disseminate and quantify benefits of accepting relatively high risk donor organs.

Efficacy and Safety of Direct-Acting Antivirals in Kidney Transplantation From HCV-Viremic Donors to Negative Recipients: A Meta-Analysis

Background:

With the development of direct-acting antiviral agents (DAAs), the research on kidney transplantation from Hepatitis C virus (HCV)-viremic donors to HCV-negative recipients has grown. The objective of this comprehensive analysis was to evaluate the efficacy and safety of DAAs in kidney transplantation from HCV-viremic donors to negative recipients.

Methods

Multiple databases were searched for a systematic and comprehensive up to March 2022. The primary outcomes included the percentage of sustained virological response at week 12 after the end of treatment (SVR12), adverse events (AEs; any grade), and severe adverse events (SAEs) as the endpoints. Publication bias was examined by using the funnel plots and Egger's test.

Results

In total, 16 studies with 454 subjects were included in the study and the pooled estimate of SVR12, AEs, and SAEs rates were 100.0% (95% CI: 99.2-100.0), 1.9%(95%CI: 0.0-4.9), and 0.0% (95%CI: 0.0-1.5). Subgroup analysis showed that pooled SVR12 rates were 100.0% (95%CI: 99.6-100.0) for genotype (GT)1a and 96.3% (95%CI: 83.3-100.0) for GT2; 100.0% (95%CI: 98.9-100.0) for DAAs treatments; and 100.0% (95%CI: 98.2-100.0) for prophylaxis subgroup. Egger's tests showed that no publication bias was found in this study.

Conclusion

This comprehensive analysis showed the high efficacy and safety of DAAs in kidney transplantation from HCV-viremic donors to HCV-negative recipients.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=246541.

Systematic Approach to Mimic Phenolic Natural Polymers for Biofabrication

In nature, phenolic biopolymers are utilized as functional tools and molecular crosslinkers to control the mechanical properties of biomaterials. Of particular interest are phenolic proteins/polysaccharides from living organisms, which are rich in catechol and/or gallol groups. Their strong underwater adhesion is attributed to the representative phenolic molecule, catechol, which stimulates intermolecular and intramolecular crosslinking induced by oxidative polymerization. Significant efforts have been made to understand the underlying chemistries, and researchers have developed functional biomaterials by mimicking the systems. Owing to their unique biocompatibility and ability to transform their mechanical properties, phenolic polymers have revolutionized biotechnologies. In this review, we highlight the bottom-up approaches for mimicking polyphenolic materials in nature and recent advances in related biomedical applications. We expect that this review will contribute to the rational design and synthesis of polyphenolic functional biomaterials and facilitate the production of related applications.

Does prolonged cold ischemia affect outcomes in donation after cardiac death donor kidney transplants?

    : The purpose of this study was to analyze the combined effect of cold ischemia time (CIT) and donation after cardiac death (DCD, with requisite warm ischemia time, WIT) on kidney transplant (KT) outcomes.

METHODS

Single center retrospective review of DCD KT recipients stratified by CIT.

RESULTS

From 6/08 to 10/20, we performed 446 DCD KTs (115 CIT ≤20, 205 CIT 20-30, 88 CIT 30-40, 38 CIT ≥40 hours). Mean WITs (26/25/27/23 minutes) and KDPI values (59%/55%/55%/59%) were similar while mean CITs (16.4/23.6/33.4/42.5 hours) and pump times (10.3/13.6/16.1/20.4 hours) differed across groups (p < 0.05). With a mean 6-year follow-up, patient survival (84%/84%/74%/84%) was similar. Kidney graft survival (GS) (72%/72%/56%/58%) and death censored GS (DCGS) (82%/80%/63%/67%) rates decreased whereas rates of primary nonfunction (PNF, 0.9%/2.4%/9.1%/7.9%) and delayed graft function (DGF) (36%/48%/50%/69%) increased with longer CIT (≥30 hours, p<0.05). Meaningful years free of dialysis, which we refer to as Allograft Life Years, were achieved in all cohorts (4.5/4.3/3.9/4.3 years per patient transplanted).

CONCLUSION

DCD donor kidneys with prolonged CIT (≥30 hours) are associated with increased rates of DGF and PNF, along with decreased GS and DCGS. Despite this, Allograft Life Years were gained even with longer CITs, demonstrating the utility of using these allografts. This article is protected by copyright. All rights reserved.

Deceased Donor Procurement Biopsy Practices, Interpretation, and Histology-Based Decision Making: A Survey of U.S. Transplant Centers

Introduction

Methods

Results

Conclusion

Desenlaces a largo plazo en pacientes trasplantados renales con donantes de criterios expandidos: experiencia de 10 años

Introducción. El trasplante renal es el tratamiento de elección para la enfermedad renal crónica. Debido a la brecha con la disponibilidad de donantes, el uso de criterios expandidos es una opción que busca mejorar la tasa de donación mundial. El objetivo de este estudio fue comparar la sobrevida del injerto y del paciente trasplantado con donante de criterios expandidos versus el donante estándar. Métodos. Cohorte retrospectiva de 1002 pacientes con trasplante renal donde se determinó la sobrevida del injerto renal y del receptor a 10 años después del trasplante. La sobrevida del injerto renal y el receptor fueron estimadas por el método de Kaplan-Meier. Una regresión de Cox fue realizada ajustando el modelo multivariado. Resultados. El análisis incluyó 1002 receptores, con un 18,8 % (n=189) que correspondían al uso de donante de criterios expandidos. El grupo de trasplante renal con donante de criterios expandidos tuvo menor sobrevida del paciente (48,1 % versus 63,8 %) y del injerto (63,3 % versus 74,7 %) en comparación con el grupo de trasplante renal con donantes con criterios estándar a los 10 años después del trasplante. La asociación de trasplante renal con donante de criterios expandidos y muerte o pérdida del injerto renal no fueron significativas cuando se ajustaron las variables en el modelo multivariado. Conclusión. El trasplante renal con donante de criterios expandidos tiene menor sobrevida del receptor y del injerto frente al grupo de trasplante renal con donante estándar. No hubo diferencias estadísticamente significativas en cuanto al trasplante renal con donante de criterios expandidos frente a la pérdida del injerto renal o muerte.

Dual kidney transplants from adult marginal donors: Review and perspective

The practice of dual kidney transplantation (DKT) from adult marginal deceased donors (MDDs) dates back to the mid-1990s with initial pioneering experiences reported by the Stanford and Maryland groups, at which time the primary indication was estimated insufficient nephron mass from older donors. Multiple subsequent studies of short and long-term success have been reported focusing on three major aspects of DKT: Identifying appropriate selection criteria and developing scoring systems based on pre- and post-donation factors; refining technical aspects; and analyzing mid-term outcomes. The number of adult DKTs performed in the United States has declined in the past decade and only about 60 are performed annually. For adult deceased donor kidneys meeting double allocation criteria, >60% are ultimately not transplanted. Deceased donors with limited renal functional capacity represent a large proportion of potential kidneys doomed to either discard or non-recovery. However, DKT may reduce organ discard and optimize the use of kidneys from MDDs. In an attempt to promote utilization of MDD kidneys, the United Network for Organ Sharing introduced new allocation guidelines pursuant to DKT in 2019. The purpose of this review is to chronicle the history of DKT and identify opportunities to improve utilization of MDD kidneys through DKT. This article is protected by copyright. All rights reserved.

Evaluating the Impact and Rationale of Race-Specific Estimations of Kidney Function: Estimations from U.S. NHANES, 2015-2018

BACKGROUND

Standard equations for estimating glomerular filtration rate (eGFR) employ race multipliers, systematically inflating eGFR for Black patients. Such inflation is clinically significant because eGFR thresholds of 60, 30, and 20 ml/min/1.73m2 guide kidney disease management. Racialized adjustment of eGFR in Black Americans may thereby affect their clinical care. In this study, we analyze and extrapolate national data to assess potential impacts of the eGFR race adjustment on qualification for kidney disease diagnosis, nephrologist referral, and transplantation listing.

METHODS

Using population-representative cross-sectional data from the United States National Health and Nutrition Examination Survey (NHANES) from 2015-2018, eGFR values for Black Americans were calculated using the Modification of Diet in Renal Disease (MDRD) equation with and without the 1.21 race-specific coefficient using cohort data on age, sex, race, and serum creatinine.

FINDINGS

Without the MDRD eGFR race adjustment, 3.3 million (10.4%) more Black Americans would reach a diagnostic threshold for Stage 3 Chronic Kidney Disease, 300,000 (0.7%) more would qualify for beneficial nephrologist referral, and 31,000 (0.1%) more would become eligible for transplant evaluation and waitlist inclusion.

INTERPRETATION

These findings suggest eGFR race coefficients may contribute to racial differences in the management of kidney. We provide recommendations for addressing this issue at institutional and individual levels.

FUNDING

No external funding was received for this study.

Kidney Allocation Policy: Past, Present, and Future

Despite an increase in the number of kidney transplants performed annually, there remain more than 90,000 individuals awaiting transplantation in the United States. As kidney transplantation has evolved, so has kidney allocation policies. The Kidney Allocation System, which was introduced in 2014, made significant strides to improve utility and equity, but regional and geographic disparities remain. Further modifications eliminating donor service areas have been introduced. Moving forward, systems involving continuous distribution and artificial intelligence may provide further advancement toward an ideal allocation system.

Peripheral Vascular Disease and Kidney Transplant Outcomes: Rethinking an Important Ongoing Complication

Peripheral vascular disease (PVD) is highly prevalent in patients on the waiting list for kidney transplantation (KT) and after transplantation and is associated with impaired transplant outcomes. Multiple traditional and nontraditional risk factors, as well as uremia- and transplant-related factors, affect 2 processes that can coexist, atherosclerosis and arteriosclerosis, leading to PVD. Some pathogenic mechanisms, such as inflammation-related endothelial dysfunction, mineral metabolism disorders, lipid alterations, or diabetic status, may contribute to the development and progression of PVD. Early detection of PVD before and after KT, better understanding of the mechanisms of vascular damage, and application of suitable therapeutic approaches could all minimize the impact of PVD on transplant outcomes. This review focuses on the following issues: (1) definition, epidemiological data, diagnosis, risk factors, and pathogenic mechanisms in KT candidates and recipients; (2) adverse clinical consequences and outcomes; and (3) classical and new therapeutic approaches.

Renal Delivery of Pharmacologic Agents During Machine Perfusion to Prevent Ischaemia-Reperfusion Injury: From Murine Model to Clinical Trials

Donor organ shortage still remains a serious obstacle for the access of wait-list patients to kidney transplantation, the best treatment for End-Stage Kidney Disease (ESKD). To expand the number of transplants, the use of lower quality organs from older ECD or DCD donors has become an established routine but at the price of increased incidence of Primary Non-Function, Delay Graft Function and lower-long term graft survival. In the last years, several improvements have been made in the field of renal transplantation from surgical procedure to preservation strategies. To improve renal outcomes, research has focused on development of innovative and dynamic preservation techniques, in order to assess graft function and promote regeneration by pharmacological intervention before transplantation. This review provides an overview of the current knowledge of these new preservation strategies by machine perfusions and pharmacological interventions at different timing possibilities: in the organ donor, ex-vivo during perfusion machine reconditioning or after implementation in the recipient. We will report therapies as anti-oxidant and anti-inflammatory agents, senolytics agents, complement inhibitors, HDL, siRNA and H2S supplementation. Renal delivery of pharmacologic agents during preservation state provides a window of opportunity to treat the organ in an isolated manner and a crucial route of administration. Even if few studies have been reported of transplantation after ex-vivo drugs administration, targeting the biological pathway associated to kidney failure (i.e. oxidative stress, complement system, fibrosis) might be a promising therapeutic strategy to improve the quality of various donor organs and expand organ availability.

Performance versus Risk Factor-Based Approaches to Coronary Artery Disease Screening in Waitlisted Kidney Transplant Candidates

INTRODUCTION

Current screening algorithms for coronary artery disease (CAD) before kidney transplantation result in many tests but few interventions.

OBJECTIVE

The aim of this study was to study the utility of 6-minute walk test (6MWT), an office-based test of cardiorespiratory fitness, for risk stratification in this setting.

METHODS

We enrolled 360 patients who are near the top of the kidney transplant waitlist at our institution. All patients underwent CAD evaluation irrespective of 6MWT results. We examined the association between 6MWT and time to CAD-related events (defined as cardiac death, revascularization, nonfatal myocardial infarction, and removal from the waitlist for CAD), treating noncardiac death and waitlist removal for non-CAD reasons as competing events.

RESULTS

The 6MWT-based approach designated approximately 45% of patients as "low risk," whereas a risk factor- or symptom-based approach designated 14 and 81% of patients as "low risk," respectively. The 6MWT-based approach was not significantly associated with CAD-related events within 1 year (subproportional hazard ratio [sHR] 1.00 [0.90-1.11] per 50 m) but was significantly associated with competing events (sHR 0.70 [0.66-0.75] per 50 m). In a companion analysis, removing waitlist status from consideration, 6MWT result was associated with the development of CAD-related events (sHR 0.92 [0.84-1.00] per 50 m).

CONCLUSIONS

The 6MWT designates fewer patients as high risk and in need of further testing (compared to risk factor-based approaches), but its utility as a pure CAD risk stratification tool is modulated by the background waitlist removal rate. CAD screening before kidney transplant should be tailored according to a patient's actual chance of receiving a transplant.

Potential Unintended Consequences of National Infectious Disease Screening Strategies in Deceased Donor Kidney Transplantation: A Cost-Effectiveness Analysis

BACKGROUND

In order to counter the lack of sufficient kidney donors, there has been interest in expanding the utilization of organs from increased infectious-risk donors. Negative nucleic acid testing of increased infectious-risk organs has been shown to increase their use as compared to only enzyme-linked immunosorbent assay negativity. However, it is not known how the expanded use of nucleic acid testing on a national scale might affect total donor utilization.

OBJECTIVE

The objective of this paper was to determine if a national screening policy requiring the use of nucleic acid testing in both increased infectious-risk and non-increased infectious-risk renal transplant donors would increase the donor organ pool.

METHODS

This study used decision-tree analysis to determine the cost-effectiveness of four US national screening policies based on an increasingly expansive use of nucleic acid testing for increased infectious-risk and non-increased infectious-risk kidneys. Parameters were taken from the literature. All costs were reported in 2020 US dollars using a Medicare payer perspective and a life-time horizon.

RESULTS

The use of nucleic acid screening solely for increased infectious-risk organs was the dominant strategy. Our results were robust to deterministic and probabilistic sensitivity analyses. One of the main driving factors of cost-effectiveness was the false-positive rate of nucleic acid testing.

CONCLUSION

Before implementing nucleic acid screening outside of increased infectious-risk organs, its false-positivity rate should be directly studied to ensure that its use does not detrimentally affect transplantation numbers, quality-adjusted life-years, and costs.

Recent progress and remaining hurdles toward clinical xenotransplantation

BACKGROUND

Xenotransplantation has made tremendous progress over the last decade.

METHODS

We discuss kidney and heart xenotransplantation, which are nearing initial clinical trials.

RESULTS

Life sustaining genetically modified kidney xenografts can now last for approximately 500 days and orthotopic heart xenografts for 200 days in non-human primates. Anti-swine specific antibody screening, preemptive desensitization protocols, complement inhibition and targeted immunosuppression are currently being adapted to xenotransplantation with the hope to achieve better control of antibody-mediated rejection (AMR) and improve xenograft longevity. These newest advances could probably facilitate future clinical trials, a significant step for the medical community, given that dialysis remains difficult for many patients and can have prohibitive costs. Performing a successful pig-to-human clinical kidney xenograft, that could last for more than a year after transplant, seems feasible but it still has significant potential hurdles to overcome. The risk/benefit balance is progressively reaching an acceptable equilibrium for future human recipients, e.g. those with a life expectancy inferior to two years. The ultimate question at this stage would be to determine if a "proof of concept" in humans is desirable, or whether further experimental/pre-clinical advances are still needed to demonstrate longer xenograft survival in non-human primates.

CONCLUSION

In this review, we discuss the most recent advances in kidney and heart xenotransplantation, with a focus on the prevention and treatment of AMR and on the recipient's selection, two aspects that will likely be the major points of discussion in the first pig organ xenotransplantation clinical trials.

Assessment of the Utility of Kidney Histology as a Basis for Discarding Organs in the United States: A Comparison of International Transplant Practices and Outcomes

BACKGROUND

Many kidneys donated for transplant in the United States are discarded because of abnormal histology. Whether histology adds incremental value beyond usual donor attributes in assessing allograft quality is unknown.

METHODS

This population-based study included patients who received a deceased donor kidney that had been biopsied before implantation according to a prespecified protocol in France and Belgium, where preimplantation biopsy findings are generally not used for decision making in the allocation process. We also studied kidneys that had been acquired from deceased United States donors for transplantation that were biopsied during allocation and discarded because of low organ quality. Using donor and recipient characteristics, we fit multivariable Cox models for death-censored graft failure and examined whether predictive accuracy (C index) improved after adding donor histology. We matched the discarded United States kidneys to similar kidneys transplanted in Europe and calculated predicted allograft survival.

RESULTS

In the development cohort of 1629 kidney recipients at two French centers, adding donor histology to the model did not significantly improve prediction of long-term allograft failure. Analyses using an external validation cohort from two Belgian centers confirmed the lack of improved accuracy from adding histology. About 45% of 1103 United States kidneys discarded because of histologic findings could be accurately matched to very similar kidneys that had been transplanted in France; these discarded kidneys would be expected to have allograft survival of 93.1% at 1 year, 80.7% at 5 years, and 68.9% at 10 years.

CONCLUSIONS

In this multicenter study, donor kidney histology assessment during allocation did not provide substantial incremental value in ascertaining organ quality. Many kidneys discarded on the basis of biopsy findings would likely benefit United States patients who are wait listed.

Early Graft Loss after Deceased-Donor Kidney Transplantation: What Are the Consequences?

BACKGROUND

Decreasing kidney discards continues to be of paramount importance for improving organ transplant access, but transplantation of nonideal deceased donor kidneys may have higher inherent risks of early graft loss (EGL). Patients with EGL (defined as graft failure within 90 days after transplant) are allowed reinstatement of waiting time according to United Network for Organ Sharing (UNOS) policy. The purpose of this study was to examine outcomes for patients experiencing EGL.

STUDY DESIGN

We performed a single center retrospective review of adult deceased donor kidney transplant (DDKT)-alone recipients from 2001 to 2018, comparing those with EGL (including primary nonfunction [PNF]) to those without.

RESULTS

EGL occurred in 103 (5.5%) of 1,868 patients, including 57 (55%) PNF, 25 (24%) deaths, 16 (16%) thrombosis, 3 (3%) rejection, and 2 (2%) disease recurrence. Kidney Donor Profile Index (KDPI) > 85% and donation after circulatory death (DCD) DDKTs did not increase risk of either EGL or PNF unless combined with prolonged cold ischemic time (CIT). For KDPI >85% with CIT >24 hours, the risk of EGL or PNF was tripled (EGL odds ratio [OR] 2.9, 95% CI 1.6-5.2; PNF OR3.6, 95% CI1.7-7.7). For DCD with CIT > 24 hours, increased risks were likewise seen for EGL (OR 2.4, 95% CI 1.3-4.3), and PNF (OR 3.2, 95% CI 1.5-7). One-year and 5-year patient survival rates were 60% and 50% after EGL, 80% and 73% after PNF, and 99% and 87% for controls, respectively. Only 24% of either EGL or PNF patients underwent retransplantation.

CONCLUSIONS

EGL and PNF were associated with low retransplantation rates and inferior patient survival. Prolonged CIT compounds risks associated with KDPI > 85% and DCD donor kidneys. Therefore, policies promoting rapid allocation and increased local use of these kidneys should be considered.

Comparison of cardiovascular mortality in hemodialysis versus peritoneal dialysis

PURPOSE

Cardiovascular disease is a significant cause of morbidity and mortality in dialysis patients. With the increasing prevalence of dialysis patients, there is a need to systematically identify the epidemiology of cardiovascular disease in hemodialysis and peritoneal dialysis patients.

METHODS

A meta-analysis was conducted in reference to the MOOSE and PRISMA guidelines. Database searches were conducted on Medline and Embase on 17 March 2020. Meta-analysis of proportions was used to summarize the overall prevalence of events. Pairwise comparisons were used to compare between hemodialysis and peritoneal dialysis, and meta-regression was applied to identify the factors influencing disease.

RESULTS

A total of 28 studies were included in the review and prevalence of cardiovascular disease events including coronary artery disease, coronary artery complications, congestive heart failure, peripheral arterial disease, atrial fibrillation, and cardiovascular mortality were summarized. Atrial fibrillation (RR 1.287 CI 1.154-1.436, p < 0.001), congestive heart failure (RR 1.229 CI 1.074-1.407, p = 0.003), and peripheral arterial disease (RR 1.132 CI 1.021-1.255, p = 0.019) were more common in hemodialysis patients, but cardiovascular mortality was lower in hemodialysis relative to peritoneal dialysis patients. (RR 0.892 CI 0.828-0.960, p = 0.002).

CONCLUSION

The authors have found fewer cardiovascular events but higher cardiovascular mortality in patients on PD as compared to those on HD. Future research is required to establish the causality between dialysis modality and the cardiovascular outcomes described.

Frailty and the Kidney Transplant Wait List: Protocol for a Multicenter Prospective Study

Background:

Understanding how frailty affects patients listed for transplantation has been identified as a priority research need. Frailty may be associated with a high risk of death or wait-list withdrawal, but this has not been evaluated in a large multicenter cohort of Canadian wait-listed patients.

Objective:

The primary objective is to evaluate whether frailty is associated with death or permanent withdrawal from the transplant wait list. Secondary objectives include assessing whether frailty is associated with hospitalization, quality of life, and the probability of being accepted to the wait list.

Design:

Prospective cohort study.

Setting:

Seven sites with established renal transplant programs that evaluate patients for the kidney transplant wait list.

Patients:

Individuals who are being considered for the kidney transplant wait list.

Measurements:

We will assess frailty using the Fried Phenotype, a frailty index, the Short Physical Performance Battery, and the Clinical Frailty Scale at the time of listing for transplantation. We will also assess frailty at the time of referral to the wait list and annually after listing in a subgroup of patients.

Methods:

The primary outcome of the composite of time to death or permanent wait-list withdrawal will be compared between patients who are frail and those who are not frail and will account for the competing risks of deceased and live donor transplantation. Secondary outcomes will include number of hospitalizations and length of stay, and in a subset, changes in frailty severity over time, change in quality of life, and the probability of being listed. Recruitment of 1165 patients will provide >80% power to identify a relative hazard of ≥1.7 comparing patients who are frail to those who are not frail for the primary outcome (2-sided α = .05), whereas a more conservative recruitment target of 624 patients will provide >80% power to identify a relative hazard of ≥2.0.

Results:

Through December 2019, 665 assessments of frailty (inclusive of those for the primary outcome and all secondary outcomes including repeated measures) have been completed.

Limitations:

There may be variation across sites in the processes of referral and listing for transplantation that will require consideration in the analysis and results.

Conclusions:

This study will provide a detailed understanding of the association between frailty and outcomes for wait-listed patients. Understanding this association is necessary before routinely measuring frailty as part of the wait-list eligibility assessment and prior to ascertaining the need for interventions that may modify frailty.

Trial Registration:

Not applicable as this is a protocol for a prospective observational study.

Survival benefit of renal transplantation in octogenarians

BACKGROUND

Elderly patients are the fastest growing population requiring renal replacement therapy. As previous studies have shown a survival benefit of kidney transplantation compared to dialysis for end-stage renal disease, we sought to evaluate if this survival benefit extends to octogenarians.

METHODS

This was a single-center retrospective cohort study of renal allograft recipients ≥80 years transplanted from 1999 to 2014 who were compared to patients listed during the same period that did not proceed to transplantation. A secondary matched group was selected from the UNOS transplant waitlist database. The primary outcome was patient survival. Secondary outcomes included graft survival and rejection incidence.

RESULTS

Thirty-three transplanted patients were compared to 71 patients waitlisted at our center and 66 patients from the UNOS database. Patients in the study group were transplanted 20.8 ± 16.1 months after listing. Patient survival was 87.8% at 6 months and 1 year and 71.4% at 3 years. Kidney transplantation was associated with a significant decrease in the risk of death after listing (HR: 0.22, CI: 0.11-0.45, P < .001).

CONCLUSION

With escalating life expectancy, kidney transplantation is a suitable treatment option in eligible octogenarians.

Multicenter Study to Transplant Hepatitis C-Infected Kidneys (MYTHIC): An Open-Label Study of Combined Glecaprevir and Pibrentasvir to Treat Recipients of Transplanted Kidneys from Deceased Donors with Hepatitis C Virus Infection

BACKGROUND

Single-center trials and retrospective case series have reported promising outcomes using kidneys from donors with hepatitis C virus (HCV) infection. However, multicenter trials are needed to determine if those findings are generalizable.

METHODS

We conducted a prospective trial at seven centers to transplant 30 kidneys from deceased donors with HCV viremia into HCV-uninfected recipients, followed by 8 weeks of once-daily coformulated glecaprevir and pibrentasvir, targeted to start 3 days posttransplant. Key outcomes included sustained virologic response (undetectable HCV RNA 12 weeks after completing treatment with glecaprevir and pibrentasvir), adverse events, and allograft function.

RESULTS

We screened 76 patients and enrolled 63 patients, of whom 30 underwent kidney transplantation from an HCV-viremic deceased donor (median kidney donor profile index, 53%) in May 2019 through October 2019. The median time between consent and transplantation of a kidney from an HCV-viremic donor was 6.3 weeks. All 30 recipients achieved a sustained virologic response. One recipient died of complications of sepsis 4 months after achieving a sustained virologic response. No severe adverse events in any patient were deemed likely related to HCV infection or treatment with glecaprevir and pibrentasvir. Three recipients developed acute cellular rejection, which was borderline in one case. Three recipients developed polyomavirus (BK) viremia near or >10,000 copies/ml that resolved after reduction of immunosuppression. All recipients had good allograft function, with a median creatinine of 1.2 mg/dl and median eGFR of 57 ml/min per 1.73 m² at 6 months.

CONCLUSIONS

Our multicenter trial demonstrated safety and efficacy of transplantation of 30 HCV-viremic kidneys into HCV-negative recipients, followed by early initiation of an 8-week regimen of glecaprevir and pibrentasvir.

Comparison of kidney allograft survival in the Eurotransplant senior program after changing the allocation criteria in 2010-A single center experience

Aims

The European Senior Program (ESP) aims to avoid waiting list competition between younger and elderly patients applying for renal transplantation. By listing patients ≥65 years on a separate waiting list and locally allocating of grafts ≥65 years exclusively to this cohort, waiting and cold ischemia times are predicted to be shortened, potentially resulting in improved kidney transplantation outcomes. This study compared a historic cohort of renal transplant recipients being simultaneously listed on the general and the ESP waiting lists with a collective exclusively listed on the ESP list in terms of surrogates of the transplantation outcome.

Methods

Total 151 eligible patients ≥ 65 years from Münster transplant Center, Germany, between 1999 and 2014 were included. Graft function, graft and patient survival were compared using surrogate markers of short- and long-term graft function. Patients were grouped according to their time of transplantation.

Results

Recipients and donors in the newESP (nESP) cohort were significantly older (69.6 ± 3.5 years vs 67.1 ± 2 years, p<0.05; 72.0 ± 5.0 years vs 70.3 ± 5.0 years, p = 0.039), had significantly shorter dialysis vintage (19.6 ± 21.7 months vs 60.2 ± 28.1 months, p<0.001) and suffered from significantly more comorbidities (2.2 ± 0.9 vs 1.8 ± 0.8, p = 0.009) than the historic cohort (HC). Five-year death-censored graft survival was better than in the HC, but 5-year graft and patient survival were better in the ESP cohort. After 2005, cold ischemia time between groups was comparable. nESP grafts showed more primary function and significantly better long-term graft function 18 months after transplantation and onwards.

Conclusion

nESP recipients received significantly older grafts, but experienced significantly shorter time on dialysis. Cold ischemia times were comparable, but graft function in the nESP cohort was significantly better in the long term.

Utilization and Outcomes of Single and Dual Kidney Transplants from Older Deceased Donors in the United Kingdom

BACKGROUND AND OBJECTIVES

Kidneys from elderly deceased donors are often discarded after procurement if the expected outcomes from single kidney transplantation are considered unacceptable. An alternative is to consider them for dual kidney transplantation. We aimed to examine the utilization of kidneys from donors aged ≥60 years in the United Kingdom and compare clinical outcomes of dual versus single kidney transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the United Kingdom Transplant Registry from 2005 to 2017 were analyzed. We examined utilization rates of kidneys retrieved from deceased donors aged ≥60 years, and 5-year patient and death-censored graft survival of recipients of dual and single kidney transplants. Secondary outcomes included eGFR. Multivariable analyses and propensity score analysis were used to correct for differences between the groups.

RESULTS

During the study period, 7841 kidneys were procured from deceased donors aged ≥60 years, of which 1338 (17%) were discarded; 356 dual and 5032 single kidneys were transplanted. Donors of dual transplants were older (median, 73 versus 66 years; P<0.001) and had higher United States Kidney Donor Risk Indices (2.48 versus 1.98; P<0.001). Recipients of dual transplants were also older (64 versus 61 years; P<0.001) and had less favorable human leukocyte antigen matching (P<0.001). After adjusting for confounders, dual and single transplants had similar 5-year graft survival (hazard ratio, 0.81; 95% CI, 0.59 to 1.12). No difference in patient survival was demonstrated. Similar findings were observed in a matched cohort with a propensity score analysis method. Median 12-month eGFR was significantly higher in the dual kidney transplant group (40 versus 36 ml/min per 1.73 m²; P<0.001).

CONCLUSIONS

Recipients of kidneys from donors aged ≥60 years have similar 5-year graft survival and better graft function at 12 months with dual compared with single deceased donor kidney transplants.

Photoacoustic imaging of kidney fibrosis for assessing pretransplant organ quality

Roughly 10% of the world's population has chronic kidney disease (CKD). In its advanced stages, CKD greatly increases the risk of hospitalization and death. Although kidney transplantation has revolutionized the care of advanced CKD, clinicians have limited ways of assessing donor kidney quality. Thus, optimal donor kidney-recipient matching cannot be performed, meaning that some patients receive damaged kidneys that function poorly. Fibrosis is a form of chronic damage often present in donor kidneys, and it is an important predictor of future renal function. Currently, no safe, easy-to-perform technique exists that accurately quantifies renal fibrosis. We describe a potentially novel photoacoustic (PA) imaging technique that directly images collagen, the principal component of fibrotic tissue. PA imaging noninvasively quantifies whole kidney fibrotic burden in mice, and cortical fibrosis in pig and human kidneys, with outstanding accuracy and speed. Remarkably, 3-dimensional PA imaging exhibited sufficiently high resolution to capture intrarenal variations in collagen content. We further show that PA imaging can be performed in a setting that mimics human kidney transplantation, suggesting the potential for rapid clinical translation. Taken together, our data suggest that PA collagen imaging is a major advance in fibrosis quantification that could have widespread preclinical and clinical impact.