Kidney graft survival in Europe and the United States: strikingly different long-term outcomes

The comparative performance of models predicting patient and graft survival after kidney transplantation: A systematic review

BACKGROUND

Cox proportional hazard models have long been the model of choice for survival prediction after kidney transplantation. In recent years, a variety of novel model types have been proposed. We investigate the prediction performance across different model types, including machine learning models and traditional model types.

METHODS

A systematic review was conducted following PROBAST and CHARMS, also considering extensions to TRIPOD+AI and PROBAST+AI, for data collection and risk of bias assessment. The review only included publications that reported on prediction performance for models of different types. A comparative analysis tested performance differences between the model types.

RESULTS

The review included 37 publications which presented 134 comparative studies. The designs of many studies left room for improvement and most studies had high risk of bias. The collected data admitted testing of performance differences for 22 pairs of model types, ten of which yielded significant differences. Support Vector Machines and Logistic Regression were never found to outperform other model types. Other comparisons, however, provide inconclusive comparative performance results and none of the model types performed consistently and significantly better than alternatives.

CONCLUSIONS

Rigorous review of current evidence and comparative performance evidence finds no significant kidney transplant survival prediction performance differences that Cox Proportional Hazard models are being outperformed. The design of many of the studies implies high risk of bias and more and better designed studies which reutilize best performing models are needed. This enables to resolve model biases, reporting issues, and to increase the power of comparative performance analysis.

Hispanic survival paradox: a systematic review of short-term hospital readmissions among Hispanic kidney transplant recipients in the United States

PURPOSE OF REVIEW

The epidemiologic phenomenon known as the "Hispanic paradox" postulates that Hispanic/Latino Americans generally tend to live longer than other racial/ethnic communities, despite facing many socioeconomic disadvantages and other healthcare barriers. Whether this phenomenon is relevant among kidney transplantation (KT) recipients remains unclear. To investigate the possibility of a Hispanic mortality advantage, we conducted a systematic review of the published literature comparing short-term KT outcomes (first 12-months) for US Hispanic versus non-Hispanic White KT recipients.

RECENT FINDINGS

This systematic review summarizes recent findings from sixteen observational retrospective cohort studies that met our study criteria. Study sample sizes ranged from 42 to 244 037 total KT recipients and examined data between 2005 and 2022. Compared to their Non-Hispanic comparator, the Hispanic sub-samples were more likely to be younger, spend more time on dialysis, and less likely to receive preemptive transplant or living donation. Hispanic KT recipients experienced similar or more favorable outcomes in eleven studies (ten studies examining patient and graft survival, one study examining readmissions), but only three studies with statistical significance.

SUMMARY

As the US Hispanic and Latino population continues to grow into the diverse American melting pot, this review highlights the need for better approaches to studying racial and ethnic variables within kidney transplantation.

GLP-1 and glucagon receptor dual agonism ameliorates kidney allograft fibrosis by improving lipid metabolism

Introduction

Kidney allograft fibrosis accelerates the progression of chronic kidney disease (CKD), leads to allograft failure, and increases patient mortality. Emerging evidence suggests that metabolic syndrome in transplant recipients is associated with fibrosis development. However, it remains unclear whether targeting metabolic pathways can mitigate allograft fibrosis. This study aimed to explore the potential of targeting metabolic pathways using the GLP-1R/GCGR dual agonist TB001 for the treatment of kidney allograft fibrosis.

Methods

Kidney allograft fibrosis was induced in rat kidney transplant models. Histological analysis, transcriptome sequencing, and in vitro experiments were performed to investigate the efficacy of TB001 and its underlying mechanisms.

Results

Compared with the control group, TB001-treated recipients had significantly improved kidney allograft function, as evidenced by lower creatinine and 24-hour urine protein levels. Moreover, TB001 treatment decreased the body weight and serum total cholesterol, LDL-cholesterol, and TNF-α levels in transplant recipients, indicating metabolic improvements. Pathological analysis demonstrated that TB001 treatment reduced inflammatory cell infiltration and downregulated the expression of fibrosis markers, including TGF-β1, α-SMA, COL1A1, and Vimentin. Further transcriptome sequencing of kidney grafts revealed that TB001-treated group had a gene expression pattern similar to that of the syngeneic control group and showed significant enhancement of lipid metabolism-related pathways, particularly the PPAR pathway. In vivo and in vitro experiments further demonstrated that TB001 upregulated the expression of CPT1A, a key molecule involved in lipid metabolism, and inhibited TGF-β1/Smad2/3/Twist and PKC-α/PKC-β pathways.

Conclusion

Targeting metabolic pathways using the GLP-1R/GCGR dual agonist TB001 shows potential for managing kidney allograft fibrosis.

A competing risks model to estimate the risk of graft failure and patient death after kidney transplantation using continuous donor-recipient age combinations

Graft failure and recipient death with functioning graft are important competing outcomes after kidney transplantation. Risk prediction models typically censor for the competing outcome thereby overestimating the cumulative incidence. The magnitude of this overestimation is not well described in real-world transplant data. This retrospective cohort study analyzed data from the European Collaborative Transplant Study (n = 125 250) and from the American Scientific Registry of Transplant Recipients (n = 190 258). Separate cause-specific hazard models using donor and recipient age as continuous predictors were developed for graft failure and recipient death. The hazard of graft failure increased quadratically with increasing donor age and decreased decaying with increasing recipient age. The hazard of recipient death increased linearly with increasing donor and recipient age. The cumulative incidence overestimation due to competing risk-censoring was largest in high-risk populations for both outcomes (old donors/recipients), sometimes amounting to 8.4 and 18.8 percentage points for graft failure and recipient death, respectively. In our illustrative model for posttransplant risk prediction, the absolute risk of graft failure and death is overestimated when censoring for the competing event, mainly in older donors and recipients. Prediction models for absolute risks should treat graft failure and death as competing events.

Unlocking Transplant Tolerance with Biomaterials

For patients suffering from organ failure due to injury or autoimmune disease, allogeneic organ transplantation with chronic immunosuppression is considered the god standard in terms of clinical treatment. However, the true "holy grail" of transplant immunology is operational tolerance, in which the recipient exhibits a sustained lack of alloreactivity toward unencountered antigen presented by the donor graft. This outcome is resultant from critical changes to the phenotype and genotype of the immune repertoire predicated by the activation of specific signaling pathways responsive to soluble and mechanosensitive cues. Biomaterials have emerged as a medium for interfacing with and reprogramming these endogenous pathways toward tolerance in precise, minimally invasive, and spatiotemporally defined manners. By viewing seminal and contemporary breakthroughs in transplant tolerance induction through the lens of biomaterials-mediated immunomodulation strategies-which include intrinsic material immunogenicity, the depot effect, graft coatings, induction and delivery of tolerogenic immune cells, biomimicry of tolerogenic immune cells, and in situ reprogramming-this review emphasizes the stunning diversity of approaches in the field and spotlights exciting future directions for research to come.

Management of bladder cancer in kidney transplant recipients: A narrative review

Background

Bladder cancer in the setting of previous a kidney transplant (KT) is challenging to manage due to complex medical and surgical considerations.

Objective

To provide a comprehensive evaluation of the scope of management of bladder cancer in KT patients, and describe the controversies surrounding these management options.

Methods

A systematic review of studies reporting management of KT patients with bladder cancer and involving ≥3 patients was performed. A narrative review was also performed for various aspects of management such as pathophysiology, surgical considerations, intravesical therapy, immunosuppression and oncological surveillance.

Results

Bladder cancer incidence in KT recipients is 2.8-4.1 times higher than the general population, and there is a notable association with aristolochic acid nephropathy as well as BK virus oncogenesis. Regarding surgical treatment, transurethral resection is preferred for non-muscle invasive tumors, and intravesical BCG for intermediate- and high-risk patients appears to be underutilized despite its safety and associated reduction in recurrence. Radical cystectomy with limited pelvic lymph node dissection, urinary diversion, and consideration of bilateral nephroureterectomy appears to be the safest method of oncological control in muscle-invasive tumors. A switch in immunosuppressive regimens to mTOR inhibitors may be considered in lieu of its antitumor effects. Routine surveillance in KT patients with risk factors for bladder cancer is challenging and may be warranted especially in the Asian population which has a higher rate of urothelial malignancy.

Conclusions

This review provides a thorough summary of management strategies for bladder cancer in the setting of previous KT.

Long-Term Results of Kidney Transplantation in Patients Aged 60 Years and Older

Background/Objectives: The results of kidney transplantation (KTx) in elderly patients are deteriorated by more frequent use of organs procured from older or extended criteria donors (ECDs). To eliminate the influence of donor factors on the transplantation results, the pair analysis method was applied. The study aimed to assess the survival, during long-term follow-up after transplantation, of recipients and transplanted kidneys, graft function, and factors influencing survival in recipients aged 60 years and older (≥60) compared to recipients aged less than 60 years (<60) who received a kidney from the same brain death donor (DBD). Methods: The study group consisted of 213 consecutive patients ≥60 who received a kidney procured from a DBD from whom the second procured kidney was transplanted to a patient <60 (control group). Results: The survival rates in the 10-year follow-up period were lower in those recipients ≥60 than in the control group (p < 0.01). The survival rates of the transplanted kidneys were comparable in both groups, while the death-censored graft survival was higher in those patients ≥60 than in the control group (p < 0.05). The estimated glomerular filtration rate levels were similar in the follow-up in patients ≥60 compared to those recipients <60. Transplantation of kidneys procured from ECD, longer duration of dialysis treatment, and longer duration of cold ischemia time (CIT) affected the recipient and graft survival in the ≥60 patients. Death-censored kidney graft survival was influenced by transplantation of a kidney procured from ECD, longer CIT, and the need for reoperation in the early postoperative period. Conclusions: Despite the higher mortality in the kidney recipients ≥60, the long-term results of KTx after the elimination of donor-dependent factors are similar or better compared to the recipients <60. The factors influencing the results of KTx in elderly recipients differ from those observed in the entire cohort and younger patients.

Disparities in lung transplantation in children

Lung transplantation is a recognized therapy for end-stage respiratory failure in children and young people. It is only available in selected countries and is limited by access to suitable organs. Data on disparities in access and outcomes for children undergoing lung transplantation are limited. It is clear from data from studies in adults, and from studies in other solid organ transplants in children, that systemic inequities exist in this field. While data relating specifically to pediatric lung transplantation are relatively sparse, professionals should be aware of the risk that healthcare systems may result in disparities in access and outcomes following lung transplantation in children.

Rapid triage and transition to telehealth for heart transplant patients in the COVID-19 pandemic setting

BACKGROUND

In the setting of the COVID-19 pandemic, a rapid uptake of telehealth services was instituted with the aim of reducing the spread of disease to vulnerable patient populations including heart transplant recipients.

METHODS

Single-center, cohort study of all heart transplant patients seen by our institution's transplant program during the first 6 weeks of transition from in-person consultation to telehealth (23 March - 5 June 2020).

RESULTS

Face-to-face consultation allocation strongly favored patients in the early post-operative period (34 vs. 242 weeks post-transplant; p < 0.001). Telehealth consultation dramatically reduced patient travel and wait times (80 min per visit saved in telehealth patients). No apparent excess re-hospitalization or mortality was seen in telehealth patients.

CONCLUSIONS

With appropriate triage, telehealth was feasible in heart transplant recipients, with videoconferencing being the preferred modality. Patients seen face-to-face were those triaged to be higher acuity based on time since transplant and overall clinical status. These patients have the expected higher rates of hospital re-admission, and therefore should continue to be seen in person.

A comparison of the epidemiology of kidney replacement therapy between Europe and the United States: 2021 data of the ERA Registry and the USRDS

BACKGROUND

This paper compares the most recent data on the incidence and prevalence of kidney replacement therapy (KRT), kidney transplantation rates, and mortality on KRT from Europe to those from the United States (US), including comparisons of treatment modalities (haemodialysis (HD), peritoneal dialysis (PD), and kidney transplantation (KTx)).

METHODS

Data were derived from the annual reports of the European Renal Association (ERA) Registry and the United States Renal Data System (USRDS). The European data include information from national and regional renal registries providing the ERA Registry with individual patient data. Additional analyses were performed to present results for all participating European countries together.

RESULTS

In 2021, the KRT incidence in the US (409.7 per million population (pmp)) was almost 3-fold higher than in Europe (144.4 pmp). Despite the substantial difference in KRT incidence, approximately the same proportion of patients initiated HD (Europe: 82%, US: 84%), PD (14%; 13%, respectively), or underwent pre-emptive KTx (4%; 3%, respectively). The KRT prevalence in the US (2436.1 pmp) was 2-fold higher than in Europe (1187.8 pmp). Within Europe, approximately half of all prevalent patients were living with a functioning graft (47%), while in the US, this was one third (32%). The number of kidney transplantations performed was almost twice as high in the US (77.0 pmp) compared to Europe (41.6 pmp). The mortality of patients receiving KRT was 1.6-fold higher in the US (157.3 per 1000 patient years) compared to Europe (98.7 per 1000 patient years).

CONCLUSIONS

The US had a much higher KRT incidence, prevalence, and mortality compared to Europe, and despite a higher kidney transplantation rate, a lower proportion of prevalent patients with a functioning graft.

Effect of Donor Cigarette Smoking in Kidney Transplantation: Re-Evaluation of Long-Term Outcomes

Cigarette smoking is a common risk factor associated with negative long-term outcomes in kidney transplant recipients. However, whether donor smoking decreases graft longevity or negatively impacts recipient survival after kidney transplantation remains unknown. Therefore, this study aims to investigate the long-term outcome in patients who received a kidney graft from a deceased smoking or non-smoking donor. A total of 580 patients were divided into two groups: patients who received a graft from a smoking donor (n = 276) and those who received a graft from a non-smoking donor (n = 304). Analysis of demographic factors showed that the non-smoking cohort was older, had more extended criteria donors and longer warm ischemia times. The primary composite endpoint of patient and graft survival was better in the smoking donor cohort when analyzed using Kaplan-Meier method but not when controlled for covariates in multivariate analyses. These findings do not support a previously reported negative impact of deceased donor smoking on kidney transplant recipients. Thus, the underlying results should not be interpreted in favor of a positive donor smoking history, but rather remind the transplant community that donor smoking should not be considered as a deciding factor in refusing an otherwise acceptable kidney graft.

Sensitive HLA antibody testing and the risk of antibody-mediated rejection and graft failure

Solid phase detection and identification of HLA antibodies in kidney transplantation currently relies on single antigen bead (Luminex®) assays, which is more sensitive than the previously used enzyme-linked immunosorbent assays (ELISA). To evaluate the impact of more sensitive HLA testing on antibody-mediated rejection (AMR) occurrence and allograft survival, we analysed 1818 renal allograft recipients transplanted between March 2004 and May 2021. In 2008, solid phase testing switched from ELISA to Luminex. We included 393 (21.6%) transplantations before and 1425 (78.4%) transplantations after transition from ELISA- to Luminex-based testing. For this study, bio-banked ELISA era samples were tested retrospectively with Luminex. Significantly less pretransplant DSA were found in patients transplanted with pre-existing HLA antibodies in the Luminex (109/387) versus the ELISA period (43/90) (28% vs. 48%, p < 0.01). Throughout histological follow-up, 169 of 1818 (9.3%) patients developed AMR. After implementing Luminex-based testing, the rate of AMR significantly decreased (p = 0.003). However, incidence of graft failure did not significantly differ between both eras. In conclusion, less patients with pretransplant DSA were transplanted since the implementation of Luminex HLA testing. Transition from ELISA- to Luminex-based HLA testing was associated with a significant decrease in AMR occurrence post-transplantation. Since the decline of AMR did not translate into improved graft survival, Luminex-based testing has the added value of preventing low-risk AMR cases. Therefore, Luminex' high sensitivity must be balanced against waiting time for a suitable organ.

Kidney transplantation in Icelandic patients, 2000-2019: are outcomes affected by low volume?

Background

In Iceland, a small number of kidney transplants from living donors (LDs) are performed at Landspitali University Hospital (LUH) in Reykjavik, while deceased donor transplants have until recently invariably been carried out abroad. In this study, we evaluated the outcome of kidney transplantation in Icelandic patients.

Methods

This was a retrospective study that included all Icelandic residents who underwent kidney transplantation between 1 January 2000 and 31 December 2019. Data were obtained from the Icelandic End-Stage Kidney Disease Registry, medical records at LUH, and the Scandiatransplant database. The Chronic Kidney Disease Epidemiology Collaboration equation was used to calculate estimated glomerular filtration rate from serum creatinine for recipients and donors aged >18 years, and the modified Schwartz equation for those aged ≤18 years. Survival was estimated using the Kaplan-Meier method, and the log-rank test was employed for group comparisons.

Results

A total of 229 kidney transplants in 221 patients were performed during the 20-year period, of which 135 (58.9%) were from LDs. Transplants carried out at LUH were 118 (51.5%), of which 116 were from LDs. During a median follow-up of 7.4 years (range 0.1-20), 27 (12.2%) patients died, 20 (74%) of whom had a functioning graft. One-year patient survival was 99.1% [95% confidence interval (CI), 97.9-100], 5-year survival was 95.7% (95% CI, 92.7-98.7), and 10-year survival was 87.7% (95% CI, 82.4-93.4). Death-censored graft survival was 98.3% (95% CI, 96.6-100), 96.8% (95% CI, 94.4-99.2), and 89.2% (95% CI, 84.1-94.7) at 1, 5, and 10 years, respectively.

Conclusions

Patient and graft survival are comparable with those of large transplant centers, demonstrating the feasibility of running a quality kidney transplant program in a small nation in collaboration with a larger center abroad.

Transplant nephrectomy: indication, surgical approach and complications-experiences from a single transplantation center

PURPOSE

Management of a failed kidney allograft, and the question whether it should be removed is a challenging task for clinicians. The reported risks for transplant nephrectomy (TN) vary, and there is no clear recommendation on indications or surgical approach that should be used. This study gives an overview of indications, compares surgical techniques, and identifies risk factors for higher morbidity.

METHODS

Retrospective analysis was conducted on all transplant nephrectomies performed between 2005 and 2020 at Charité Hospital Berlin, Department of Urology. Patient demographics, laboratory parameters, graft survival data, indication for TN, and surgical complications were extracted from medical reports.

RESULTS

A total of 195 TN were performed, with graft intolerance syndrome being the most common indication in 52 patients (26.7%), acute rejection in 36 (18.5%), acute infection in 30 (15.4%), and other reasons to stop immunosuppression in 26 patients (13.3%). Rare indications were vascular complications in 16 (8.2%) and malignancies in the allograft in six (3.1%) cases. Extracapsular surgical approach was significantly more often used in cases of vascular complications and earlier allograft removal, but there was no difference in complication rates between extra- and intracapsular approach. Acute infection was identified as an independent risk factor for a complication grade IIIb or higher according to Clavien-Dindo classification, with a HR of 12.3 (CI 2.2-67.7; p = 0.004).

CONCLUSION

Transplant nephrectomy should only be performed when there is a good indication, and non-elective surgery should be avoided, when possible, as it increases morbidity.

Comparison of 2 Immunosuppression Minimization Strategies in Kidney Transplantation: The ALLEGRO Trial

BACKGROUND

Evidence on the optimal maintenance of immunosuppressive regimen in kidney transplantation recipients is limited.

METHODS

The Amsterdam, LEiden, GROningen trial is a randomized, multicenter, investigator-driven, noninferiority, open-label trial in de novo kidney transplant recipients, in which 2 immunosuppression minimization strategies were compared with standard immunosuppression with basiliximab, corticosteroids, tacrolimus, and mycophenolic acid. In the minimization groups, either steroids were withdrawn from day 3, or tacrolimus exposure was reduced from 6 mo after transplantation. The primary endpoint was kidney transplant function at 24 mo.

RESULTS

A total of 295 participants were included in the intention-to-treat analysis. Noninferiority was shown for the primary endpoint; estimated glomerular filtration rate at 24 mo was 45.3 mL/min/1.73 m 2 in the early steroid withdrawal group, 49.0 mL/min/1.73 m 2 in the standard immunosuppression group, and 44.7 mL/min/1.73 m 2 in the tacrolimus minimization group. Participants in the early steroid withdrawal group were significantly more often treated for rejection ( P = 0.04). However, in this group, the number of participants with diabetes mellitus during follow-up and total cholesterol at 24 mo were significantly lower.

CONCLUSIONS

Tacrolimus minimization can be considered in kidney transplant recipients who do not have an increased immunological risk. Before withdrawing steroids the risk of rejection should be weighed against the potential metabolic advantages.

Baduanjin exercise intervention trial: research protocol of a randomised controlled trial for frail kidney transplant recipients

INTRODUCTION

Frailty is one of the most common comorbidities in kidney transplant recipients (KTRs). Physical, psychological and social frailty could be improved by exercise intervention. Baduanjin, also known as Eight-section Brocades, is a type of traditional Chinese medicine exercise characterised by the interplay between physical postures and movements, breathing and mind. It can help frail patients strengthen their upper and lower body muscles, improve their mood, quality of life and frailty. However, the effectiveness of Baduanjin on frail KTRs remains unknown. Therefore, we will conduct a randomised controlled trial (RCT) to evaluate the effectiveness of Baduanjin on frail KTRs.

METHODS AND ANALYSIS

This protocol describes an assessor and analyst blinded, parallel RCT for frail KTRs comparing Baduanjin group (n=72) with care-as-usual group (n=72). The primary outcomes are frailty assessed by Frailty Phenotype scale and Tilburg Frailty Indicator scale, and muscle strength assessed by a grip strength metre. The secondary outcomes are quality of life assessed by Medical Outcomes Study 36-Item Short-Form Health Survey (MOS SF-36) and depression assessed by the Hospital Anxiety and Depression Scale. All these data will be collected at the baseline, after 3, 6, 9 and 12 months, respectively. Two-way mixed analysis of variance (ANOVA) will be used to test the effectiveness of Baduanjin exercise. Qualitative interviews with participants in the intervention group will also be performed after 6 months. Themes will be extracted from interview transcripts using NVivo software.

ETHICS AND DISSEMINATION

The Ethics Committees of Beijing University of Chinese Medicine (2022BZYLL1018) and China-Japan Friendship Hospital (2022-KY-250) had approved the study. The organ donors were all from China-Japan Friendship Hospital. They provided informed consent and they were not executed prisoners. We have provided BMJ Open with documentation from the hospital that indicates that the organs will be harvested ethically. The findings of this study will be disseminated through peer-reviewed journals, international conferences, media reports and briefings.

TRIAL REGISTRATION NUMBER

ChiCTR2100041730.

Mitigating Health Disparities in Transplantation Requires Equity, Not Equality

Despite decades of research and evidence-based mitigation strategies, disparities in access to transplantation persist for all organ types and in all stages of the transplant process. Although some strategies have shown promise for alleviating disparities, others have fallen short of the equity goal by providing the same tools and resources to all rather than tailoring the tools and resources to one's circumstances. Innovative solutions that engage all stakeholders are needed to achieve equity regardless of race, sex, age, socioeconomic status, or geography. Mitigation of disparities is paramount to ensure fair and equitable access for those with end-stage disease and to preserve the trust of the public, upon whom we rely for their willingness to donate organs. In this overview, we present a summary of recent literature demonstrating persistent disparities by stage in the transplant process, along with policies and interventions that have been implemented to combat these disparities and hypotheses for why some strategies have been more effective than others. We conclude with future directions that have been proposed by experts in the field and how these suggested strategies may help us finally arrive at equity in transplantation.

Hematopoietic cell-based and non-hematopoietic cell-based strategies for immune tolerance induction in living-donor renal transplantation: A systematic review

INTRODUCTION

Despite its use to prevent acute rejection, lifelong immunosuppression can adversely impact long-term patient and graft outcomes. In theory, immunosuppression withdrawal is the ultimate goal of kidney transplantation, and is made possible by the induction of immunological tolerance. The purpose of this paper is to review the safety and efficacy of immune tolerance induction strategies in living-donor kidney transplantation, both chimerism-based and non-chimerism-based. The impact of these strategies on transplant outcomes, including acute rejection, allograft function and survival, cost, and immune monitoring, will also be discussed.

MATERIALS AND METHODS

Databases such as PubMed, Scopus, and Web of Science, as well as additional online resources such as EBSCO, were exhaustively searched. Adult living-donor kidney transplant recipients who developed chimerism-based tolerance after concurrent bone marrow or hematopoietic stem cell transplantation or those who received non-chimerism-based, non-hematopoietic cell therapy using mesenchymal stromal cells, dendritic cells, or regulatory T cells were studied between 2000 and 2021. Individual sources of evidence were evaluated critically, and the strength of evidence and risk of bias for each outcome of the transplant tolerance study were assessed.

RESULTS

From 28,173 citations, 245 studies were retrieved after suitable exclusion and duplicate removal. Of these, 22 studies (2 RCTs, 11 cohort studies, 6 case-control studies, and 3 case reports) explicitly related to both interventions (chimerism- and non-chimerism-based immune tolerance) were used in the final review process and were critically appraised. According to the findings, chimerism-based strategies fostered immunotolerance, allowing for the safe withdrawal of immunosuppressive medications. Cell-based therapy, on the other hand, frequently did not induce tolerance except for minimising immunosuppression. As a result, the rejection rates, renal allograft function, and survival rates could not be directly compared between these two groups. While chimerism-based tolerance protocols posed safety concerns due to myelosuppression, including infections and graft-versus-host disease, cell-based strategies lacked these adverse effects and were largely safe. There was a lack of direct comparisons between HLA-identical and HLA-disparate recipients, and the cost implications were not examined in several of the retrieved studies. Most studies reported successful immunosuppressive weaning lasting at least 3 years (ranging up to 11.4 years in some studies), particularly with chimerism-based therapy, while only a few investigators used immune surveillance techniques. The studies reviewed were often limited by selection, classification, ascertainment, performance, and attrition bias.

CONCLUSIONS

This review demonstrates that chimerism-based hematopoietic strategies induce immune tolerance, and a substantial number of patients are successfully weaned off immunosuppression. Despite the risk of complications associated with myelosuppression. Non-chimerism-based, non-hematopoietic cell protocols, on the other hand, have been proven to facilitate immunosuppression minimization but seldom elicit immunological tolerance. However, the results of this review must be interpreted with caution because of the non-randomised study design, potential confounding, and small sample size of the included studies. Further validation and refinement of tolerogenic protocols in accordance with local practice preferences is also warranted, with an emphasis on patient selection, cost ramifications, and immunological surveillance based on reliable tolerance assays.

KiT-GENIE, the French genetic biobank of kidney transplantation

KiT-GENIE is a monocentric DNA biobank set up to consolidate the very rich and homogeneous DIVAT French cohort of kidney donors and recipients (D/R) in order to explore the molecular factors involved in kidney transplantation outcomes. We collected DNA samples for kidney transplantations performed in Nantes, and we leveraged GWAS genotyping data for securing high-quality genetic data with deep SNP and HLA annotations through imputations and for inferring D/R genetic ancestry. Overall, the biobank included 4217 individuals (n = 1945 D + 2,272 R, including 1969 D/R pairs), 7.4 M SNPs and over 200 clinical variables. KiT-GENIE represents an accurate snapshot of kidney transplantation clinical practice in Nantes between 2002 and 2018, with an enrichment in living kidney donors (17%) and recipients with focal segmental glomerulosclerosis (4%). Recipients were predominantly male (63%), of European ancestry (93%), with a mean age of 51yo and 86% experienced their first graft over the study period. D/R pairs were 93% from European ancestry, and 95% pairs exhibited at least one HLA allelic mismatch. The mean follow-up time was 6.7 years with a hindsight up to 25 years. Recipients experienced biopsy-proven rejection and graft loss for 16.6% and 21.3%, respectively. KiT-GENIE constitutes one of the largest kidney transplantation genetic cohorts worldwide to date. It includes homogeneous high-quality clinical and genetic data for donors and recipients, hence offering a unique opportunity to investigate immunogenetic and genetic factors, as well as donor-recipient interactions and mismatches involved in rejection, graft survival, primary disease recurrence and other comorbidities.

Long term outcomes following kidney transplantation in children who weighed less than 15 kg - report from the UK Transplant Registry

BACKGROUND

Kidney transplantation is the treatment of choice in chronic kidney disease (CKD) stage 5. It is often delayed in younger children until a target weight is achieved due to technical feasibility and historic concerns about poorer outcomes.

METHODS

Data on all first paediatric (aged < 18 years) kidney only transplants performed in the United Kingdom between 1 January 2006 and 31 December 2016 were extracted from the UK Transplant Registry (n = 1,340). Children were categorised by weight at the time of transplant into those < 15 kg and those ≥ 15 kg. Donor, recipient and transplant characteristics were compared between groups using chi-squared or Fisher's exact test for categorical variables and Kruskal-Wallis test for continuous variables. Thirty day, one-year, five-year and ten-year patient and kidney allograft survival were compared using the Kaplan-Meier method.

RESULTS

There was no difference in patient survival following kidney transplantation when comparing children < 15 kg with those ≥ 15 kg. Ten-year kidney allograft survival was significantly better for children < 15 kg than children ≥ 15 kg (85.4% vs. 73.5% respectively, p = 0.002). For children < 15 kg, a greater proportion of kidney transplants were from living donors compared with children ≥ 15 kg (68.3% vs. 49.6% respectively, p < 0.001). There was no difference in immediate graft function between the groups (p = 0.54) and delayed graft function was seen in 4.8% and 6.8% of children < 15 kg and ≥ 15 kg respectively.

CONCLUSIONS

Our study reports significantly better ten-year kidney allograft survival in children < 15 kg and supports consideration of earlier transplantation for children with CKD stage 5. A higher resolution version of the Graphical abstract is available as Supplementary information.

Transcriptome analysis of renal ischemia/reperfusion (I/R) injury in BAFF and BAFF-R deficient mice

Acute kidney injury (AKI) accompanies with high morbidity and mortality. Incomplete renal recovery can lead to chronic and finally end-stage kidney disease, which results in the requirement of lifelong dialysis or kidney transplantation. Consequently, finding predictive biomarker and therefore developing preventive therapeutic approaches is an urgent need. For this purpose, a better understanding of the mechanism underlying AKI is necessary. The cytokine BAFF (B cell activating factor) is related to AKI by supporting B cells, which in turn play an important role in inflammatory processes and the production of antibodies. In our study, we investigated the role of BAFF and its receptor BAFF-R in the early phase of AKI. Therefore, we performed the well-established ischemia/reperfusion (I/R) model in BAFF (B6.129S2-Tnfsf13btm1Msc/J) and BAFF-R (B6(Cg)-Tnfrsf13ctm1Mass/J) deficient mice. Transcriptome of ischemic and contralateral control kidneys was analyzed and compared to wildtype littermates. We detected the upregulation of Lcn2, Lyz2, Cd44, Fn1 and Il1rn in ischemic kidneys as well as the downregulation of Kl. Furthermore, we revealed different expression patterns in BAFF and BAFF-R knockout mice. Compared to wildtype littermates, up- and downregulation of each investigated gene were higher in BAFF-R knockout and lower in BAFF knockout. Our findings indicate a positive impact of BAFF knockout in early phase of AKI, while BAFF-R knockout seems to worsen I/R injury. In addition, our study shows for the first time a remarkable renal upregulation of Lyz2 in a murine I/R model. Therefore, we consider Lyz2 as conceivable predictive or early biomarker in case of I/R and AKI.

The Effect of Elective Ligation of the Arteriovenous Fistula on Cardiac and Renal Functions in Kidney Transplant Recipients

Key Points

Surgical AVF ligation in KTRs is associated with a significant increase in diastolic BP while systolic BP remains stable. AVF closure in KTRs leads to an improvement of LV and LA morphology and a decrease in serum NT-proBNP levels. There is no significant effect of AVF ligation on kidney allograft function: The eGFR remains stable over time.

Background

Kidney transplantation is considered as the best kidney replacement therapy, and arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis. The systematic ligation of a functioning AVF in stable kidney transplant recipients (KTRs) remains debatable.

Methods

In this prospective study, we investigated the hemodynamic effect of the surgical closure of AVF in KTRs. Forty-three KTRs underwent an ambulatory BP monitoring before surgical closure of AVF (T0) and 12 months later (M12), as well as measurement of serum cardiac biomarkers (i.e. , soluble suppression of tumorigenicity 2, N-terminal pro b-type natriuretic peptide [NT-proBNP], and galectin-3). Serum tests were also performed 6 months after AVF closure (M6). An echocardiographic examination was performed at each time point. All serum creatinine values were collected to compare the individual eGFR slopes before versus after AVF closure. The latest measure of the AVF flow before kidney transplantation was recorded.

Results

Diastolic BP significantly rose from T0 to M12: +4.4±7.3 mm Hg (P = 0.0003) for 24h, +3.8±7.4 mm Hg (P = 0.0018) during the day, and +6.3±9.9 mm Hg (P = 0.0002) during the night, leading to an increased proportion of KTRs with European Society of Hypertension (ESH)-defined arterial hypertension after AVF ligation. No change was observed for systolic BP. NT-proBNP significantly dropped between T0 and M6 (345 [190; 553] to 230 [118; 458] pg/ml, P = 0.0001) and then remained stable from M6 to M12 while suppression of tumorigenicity 2 and galectin-3 levels did not change from T0 to M12. We observed a significant decrease in left ventricular (LV) end-diastolic volume, LV end-systolic volume, LV mass, interventricular septum diameter, left atrial volume, and tricuspid annular plane systolic excursion from T0 to M6 and then a stability from M6 to M12. LV ejection fraction and eGFR slope remained stable during the whole study. These observations remained unchanged after adjustment for AVF flow.

Conclusion

The closure of a patent AVF in KTRs is associated with elevation of diastolic BP, drop in serum NT-proBNP levels, reduction of left ventricular and atrial dimensions, and stability of eGFR slope.

Lowering maintenance immune suppression in elderly kidney transplant recipients; connecting the immunological and clinical dots

The management of long-term immune suppressive medication in kidney transplant recipients is a poorly explored field in the area of transplant medicine. In particular, older recipients are at an increased risk for side effects and have an exponentially increased risk of infection-related death. In contrast, an aged immune system decreases the risk of acute T-cell-mediated rejection in older recipients. Recent advances in alloimmunity research have shown a rapid and substantial decline in polyfunctional, high-risk CD4⁺ T cells post-transplantation. This lowers the direct alloreactivity responsible for T-cell-mediated rejection, also known as donor-specific hyporesponsiveness. Chronic antibody-mediated rejection (c-aABMR) is the most frequent cause of kidney graft loss in the long term. However, in older adults, c-aABMR as a cause of graft loss is outnumbered by death with a functioning graft. In addition, DSA development and a diagnosis of c-aABMR plateau ~10 years after transplantation, resulting in a very low risk for rejection thereafter. The intensity of immune suppression regimes could likely be reduced accordingly, but trials in this area are scarce. Tacrolimus monotherapy for 1 year after transplantation seems feasible in older kidney transplant recipients with standard immunological risk, showing the expected benefits of fewer infections and better vaccination responses.

A multinational cohort study uncovered sex differences in excess mortality after kidney transplant

Worldwide and at all ages, males have a higher mortality risk than females. This mortality bias should be preserved in kidney transplant recipients unless there are sex differences in the effects of transplantation. Here we compared the excess risk of mortality (risk above the general population) in female versus male recipients of all ages recorded in three large transplant databases. This included first deceased donor kidney transplant recipients and accounted for the modifying effects of donor sex and recipient age. After harmonization of variables across cohorts, relative survival models were fitted in each cohort separately and results were combined using individual patient data meta-analysis among 466,892 individuals (1988-2019). When the donor was male, female recipients 0-12 years (Relative Excess Risk 1.54, 95% Confidence Interval 1.20-1.99), 13-24 years (1.17, 1.01-1.34), 25-44 years (1.11, 1.05-1.18) and 60 years and older (1.05, 1.02-1.08) showed higher excess mortality risks than male recipients of the same age. When the donor was female, the Relative Excess Risk for those over 12 years were similar to those when the donor was male. There is a higher excess mortality risk in female than male recipients with differences larger at younger than older ages and only statistically significant when the donor was male. While these findings may be partly explained by the known sex differences in graft loss risks, sex differences in the risks of death with graft function may also contribute. Thus, higher risks in females than males suggest that management needs to be modified to optimize transplant outcomes among females.

Long-term Prolonged-release Tacrolimus-based Immunosuppression in De Novo Kidney Transplant Recipients: 5-Y Prospective Follow-up of Patients in the ADVANCE Study

Although prolonged-release tacrolimus (PR-T) is widely approved for posttransplantation immunosuppression in kidney recipients, large-scale studies are required to assess long-term outcomes. We present follow-up data from the Advagraf-based Immunosuppression Regimen Examining New Onset Diabetes Mellitus in Kidney Transplant Recipients (ADVANCE) trial, in which kidney transplant patients (KTPs) received corticosteroid minimization with PR-T.

Methods

ADVANCE was a 24-wk, randomized, open-label, phase-4 study. De novo KTPs received PR-T with basiliximab and mycophenolate mofetil and were randomized to receive an intraoperative corticosteroid bolus plus tapered corticosteroids until day 10 (arm 1) or an intraoperative corticosteroid bolus (arm 2). In this 5-y, noninterventional follow-up, patients received maintenance immunosuppression according to standard practice. The primary endpoint was graft survival (Kaplan-Meier). Secondary endpoints included patient survival, biopsy-confirmed acute rejection-free survival, and estimated glomerular filtration rate (4-variable modification of diet in renal disease).

Results

Follow-up study included 1125 patients. Overall graft survival at 1 and 5 y posttransplantation was 93.8% and 88.1%, respectively, and was similar between treatment arms. At 1 and 5 y, patient survival was 97.8% and 94.4%, respectively. Five-year graft and patient survival rates in KTPs who remained on PR-T were 91.5% and 98.2%, respectively. Cox proportional hazards analysis demonstrated similar risk of graft loss and death between treatment arms. Five-year biopsy-confirmed acute rejection-free survival was 84.1%. Mean ± standard deviation values of estimated glomerular filtration rate were 52.7 ± 19.5 and 51.1 ± 22.4 mL/min/1.73 m² at 1 and 5 y, respectively. Fifty adverse drug reactions were recorded, probably tacrolimus-related in 12 patients (1.5%).

Conclusions

Graft survival and patient survival (overall and for KTPs who remained on PR-T) were numerically high and similar between treatment arms at 5 y posttransplantation.

Comparative Study of the Impact of Human Leukocyte Antigens on Renal Transplant Survival in Andalusia and the United States

Renal transplantation is the treatment of choice for patients suffering from chronic renal disease, one of the leading causes of death worldwide. Among the biological barriers that may increase the risk of acute renal graft rejection is the presence of human leukocyte antigen (HLA) incompatibilities between donor and recipient. This work presents a comparative study of the influence of HLA incompatibilities on renal transplantation survival in the Andalusian (South of Spain) and United States (US) population. The main objective is to analyse the extent to which results about the influence of different factors on renal graft survival can be generalised to different populations. The Kaplan-Meier estimator and the Cox model have been used to identify and quantify the impact on the survival probability of HLA incompatibilities, both in isolation and in conjunction with other factors associated with the donor and recipient. According to the results obtained, HLA incompatibilities considered in isolation have negligible impact on renal survival in the Andalusian population and a moderate impact in the US population. Grouping by HLA score presents some similarities for both populations, while the sum of all HLA scores (aHLA) only has an impact on the US population. Finally, the graft survival probability of the two populations differs when aHLA is considered in conjunction with blood type. The results suggest that the disparities in the renal graft survival probability between the two populations under study are due not only to biological and transplantation-associated factors, but also to social-health factors and ethnic heterogeneity between populations.

A systematic review of social determinants of health in pediatric organ transplant outcomes

BACKGROUND

Equitable access to pediatric organ transplantation is critical, although risk factors negatively impacting pre- and post-transplant outcomes remain. No synthesis of the literature on SDoH within the pediatric organ transplant population has been conducted; thus, the current systematic review summarizes findings to date assessing SDoH in the evaluation, listing, and post-transplant periods.

METHODS

Literature searches were conducted in Web of Science, Embase, PubMed, and Cumulative Index to Nursing and Allied Health Literature databases.

RESULTS

Ninety-three studies were included based on pre-established criteria and were reviewed for main findings and study quality. Findings consistently demonstrated disparities in key transplant outcomes based on racial or ethnic identity, including timing and likelihood of transplant, and rates of rejection, graft failure, and mortality. Although less frequently assessed, variations in outcomes based on geography were also noted, while findings related to insurance or SES were inconsistent.

CONCLUSION

This review underscores the persistence of SDoH and disparity in equitable transplant outcomes and discusses the importance of individual and systems-level change to reduce such disparities.

CYP3A5 Expressor Genotype of the Transplanted Kidney Increases the Risk of Preterm Graft Loss and Acute Rejection

INTRODUCTION

Tacrolimus is metabolized mainly in the liver by the CYP3A enzyme family, with a particularly well-documented role of CYP3A5. CYP3A5 is also expressed in the renal tissue and is present in the transplanted kidney. To date, the association between donor CYP3A5 polymorphisms and transplant outcome remains poorly understood. The aim of this study was to assess the effect of donor CYP3A5 expression on early and long-term transplant outcomes.

METHODS

A retrospective cohort study including 207 patients who received kidney grafts from 110 deceased donors was conducted at a single Central European Center. Tissue samples from all donors were studied for CYP3A5 single-nucleotide polymorphism (rs776746). Death-censored graft loss within 5-year follow-up, acute rejection occurrence, and kidney function, measured using serum creatinine and MDRD eGFR, were compared between groups of patients with allografts from rs776746 carriers (CYP3A5 expressors) and noncarriers (CYP3A5 nonexpressors).

RESULTS

Recipients who received kidneys from CYP3A5 expressors (n = 24) were at significantly higher risk of death-censored graft loss within 5-year follow-up (adjusted HR, 95% CI: 6.82, 2.01-23.12; p = 0.002) and acute rejection within the 1st posttransplant year (adjusted OR, 95% CI: 4.62, 1.67-12.77; p = 0.003) than those who did not (n = 183). The median time to loss of function was 1.93 [IQR; 0.77-3.19] years.

CONCLUSIONS

Donor CYP3A5 expressor status is associated with worse renal graft survival and a higher risk of acute rejection. Determination of donor CYP3A5 genotype is a potentially useful tool that may improve kidney transplant outcomes.

Protocol for the AKT-MP trial: Access to Kidney Transplantation in Minority Populations

Background

Kidney transplant (KT) is the optimal treatment for kidney failure (KF), and although completion of KT evaluation is an essential step in gaining access to transplantation, the process is lengthy, time consuming, and burdensome. Furthermore, despite similar referral rates to non-Hispanic Whites, both Hispanic/Latinos and American Indians are less likely to be wait-listed or to undergo KT.

Methods

The Access to Kidney Transplantation in Minority Populations (AKT-MP) Trial compares two patient-centered methods to facilitate KT evaluation: kidney transplant fast track (KTFT), a streamlined KT evaluation process; and peer navigators (PN), a peer-assisted evaluation program that incorporates motivational interviewing. This pragmatic randomized trial will use a comparative effectiveness approach to assess whether KTFT or PN can help patients overcome barriers to transplant listing. We will randomly assign patients to the two conditions. We will track participants' medical records and conduct surveys prior to their initial evaluation clinic visit and again after they complete or discontinue evaluation.

Conclusion

Our aims are to (1) compare KTFT and PN to assess improvements in kidney transplant (KT) related outcomes and cost effectiveness; (2) examine how each approach effects changes in cultural/contextual factors, KT concerns, KT knowledge, and KT ambivalence; and (3) develop a framework for widespread implementation of either approach. The results of this trial will provide key information for facilitating the evaluation process, improving patient care, and decreasing disparities in KT.

Comparison of Kidney Transplantation Outcomes Between Patients with and Without Pre-transplantation Bariatric Surgery: a Systematic Review

This systematic review evaluated the impact of bariatric surgery, performed to improve eligibility for kidney transplantation, on post-transplantation outcomes. A systematic literature search was performed for articles published by 30 January 2022. A total of 31 studies were included. Among patients without pre-transplantation bariatric surgery, 18 studies reported 13.7% graft loss and 9.1% mortality within 5 years' post-transplantation. Among recipients with pre-transplantation bariatric surgery, 15 studies reported 8.7% graft loss and 2.8% mortality within 1 month to over 5 years' post-transplantation. Two case-control studies comparing post-transplantation outcomes between recipients with and without prior bariatric surgery demonstrated no significant differences between groups for graft loss, patient mortality, delayed graft function, wound complications and lymphocele. Non-randomized selection of patients and different lengths of follow-up limit the results of this study.

Long-term outcomes of kidney transplantation from expanded criteria donors with Chinese novel donation policy: donation after citizens' death

Introduction

The Chinese Government initiated the Donation after Citizens' Death policy in 2010. To now, it has been a major source of organs for transplant. Since it is still a young policy, corresponding clinical evidence is still urgently needed for its improvement. Compared to kidneys donated by SCD (standard criteria donor), increasing the use of ECD (expanded criteria donor) derived kidneys is a way to expand the donor pool but is also a result of the aging demography of China. This study is based on the data of kidney transplantation in our center with the Donation after Citizens' Death policy, aiming to provide a reference for the clinical use of ECD kidneys.

Method

A retrospective study enrolled 415 kidney transplants derived from 211 donors performed between October 2011 and October 2019. A total of 311 (74.9%) organs were donated from 159 (75.4%) SCDs, and the remaining 104 (25.1%) were from 52 (24.6%) ECDs. The log-rank test was used to compare the difference in survival and postoperative complications. The Chi-square test was used to compare the occurrence of postoperative complications and postoperative renal function. The Cox regression analysis was used for risk factor screening.

Result

Analysis showed that grafts from ECD were poorer in survival (P = 0.013), while their recipients had comparable (P = 0.16) survival. Moreover, it also was an independent risk factor for graft loss (HR 2.27, P = 0.044). There were significantly more AR occurrences in the ECD group compared with SCD group (25.0% vs. 15.8%, P = 0.004), but no significant difference was found in infection (51.9% vs. 47.6%, P = 0.497) and DGF (26.0% vs. 21.9%, P = 0.419) between them. Similarly, fewer recipients in the ECD group were free from AR within 1 year after transplantation (P = 0.040), with no statistical difference in all-cause infection prevalence in 1 year (P = 0.168). The eGFR in the ECD group was significantly worse than that in the SCD group at 3 months, 6 months, 1 year, 3 years, and the highest value posttransplant (all < 0.05), but no difference at 5 years posttransplant. Besides, results showed cardiac arrest (uncontrolled vs. controlled, HR 2.49, P = 0.049), HLA mismatch (4–6 loci vs. 0–3 loci, HR 3.61, P = 0.039), and AR occurrence (HR 2.91, P = 0.006) were demonstrated to be independent risk factors for graft loss.

Conclusion

The ECD-derived kidney was worse than the SCD-derived kidney in terms of graft survival and AR occurrence, and trend to an inferior renal function postoperative. However, the recipient survival, DGF occurrence, and all-cause infection occurrence were similar.

The Impact of Human Microbiotas in Hematopoietic Stem Cell and Organ Transplantation

The human microbiota heavily influences most vital aspects of human physiology including organ transplantation outcomes and transplant rejection risk. A variety of organ transplantation scenarios such as lung and heart transplantation as well as hematopoietic stem cell transplantation is heavily influenced by the human microbiotas. The human microbiota refers to a rich, diverse, and complex ecosystem of bacteria, fungi, archaea, helminths, protozoans, parasites, and viruses. Research accumulating over the past decade has established the existence of complex cross-species, cross-kingdom interactions between the residents of the various human microbiotas and the human body. Since the gut microbiota is the densest, most popular, and most studied human microbiota, the impact of other human microbiotas such as the oral, lung, urinary, and genital microbiotas is often overshadowed. However, these microbiotas also provide critical and unique insights pertaining to transplantation success, rejection risk, and overall host health, across multiple different transplantation scenarios. Organ transplantation as well as the pre-, peri-, and post-transplant pharmacological regimens patients undergo is known to adversely impact the microbiotas, thereby increasing the risk of adverse patient outcomes. Over the past decade, holistic approaches to post-transplant patient care such as the administration of clinical and dietary interventions aiming at restoring deranged microbiota community structures have been gaining momentum. Examples of these include prebiotic and probiotic administration, fecal microbial transplantation, and bacteriophage-mediated multidrug-resistant bacterial decolonization. This review will discuss these perspectives and explore the role of different human microbiotas in the context of various transplantation scenarios.

Age-dependent Sex Differences in Graft Loss After Kidney Transplantation

BACKGROUND

Sex differences in kidney graft loss rates were reported in the United States. Whether these differences are present in other countries is unknown.

METHODS

We estimated the association between recipient sex and death-censored graft loss in patients of all ages recorded in the Scientific Registry of Transplant Recipients, Australia and New Zealand Dialysis and Transplant Registry, and Collaborative Transplant Study registries who received a first deceased donor kidney transplant (1988-2019). We used multivariable Cox regression models, accounting for the modifying effects of donor sex and recipient age, in each registry separately; results were combined using individual patient data meta-analysis.

RESULTS

We analyzed 438 585 patients. Young female patients 13-24 y old had the highest crude graft loss rates (female donor: 5.66; male donor: 5.50 per 100 person-years). Among young recipients of male donors, females showed higher graft loss risks than males (0-12 y: adjusted hazard ratio [aHR] 1.42, (95% confidence interval [CI], 1.17-1.73); 13-24 y: 1.24 (1.17-1.32); 25-44 y: 1.09 (1.06-1.13)). When the donor was female, there were no significant differences by recipient sex among those of age <45 y; however, the aHR for females was 0.93 (0.89-0.98) in 45-59 y-old and 0.89 (0.86-0.93) in ≥ 60 y-old recipients. Findings were similar for all 3 registries in most age intervals; statistically significant heterogeneity was seen only among 13-24-y-old recipients of a female donor (I2 = 71.5%, P = 0.03).

CONCLUSIONS

There is an association between recipient sex and kidney transplantation survival that is modified by recipient age and donor sex.

Causes of Kidney Graft Failure in a Cohort of Recipients With a Very Long-Time Follow-Up After Transplantation

Background

Biopsy-proven causes of graft loss many years after kidney transplantation are scarcely documented.

Methods

Patients transplanted between 1995 and 2005 (n = 737) in a single center were followed on a regular basis until 2021. The recipients were divided according to age at transplantation into 3 groups; 18–39 years (young), 40–55 years (middle age), and older than 55 years (elderly). For cause biopsies of renal transplants were clustered into the categories, rejection, IFTA, return original disease, and diagnosis of de novo kidney disease.

Results

Rejection was the main cause of graft failure censored for death at every time period after transplantation. The incidence of T cell-mediated rejection (TCMR) became rare 6 years after transplantation while the cumulative incidence of antibody-mediated rejection (ABMR) increased over time (1.1% per year). ABMR was not diagnosed anymore beyond 15 years of follow-up in recipients without pre-transplant donor-specific antibodies (DSA). An episode of TCMR was associated with an increased incidence of ABMR diagnosis in the short-term but did not increase the overall incidence of AMBR not in the long-term. Death as a cause of graft failure was an important competitive risk factor long after transplantation and resulted in a significantly lower frequency of rejection-related graft loss in the elderly group (11 vs. 23% in the young group at 15 year follow-up).

Conclusion

Rejection is a major cause of graft loss but recipient’s age, time after transplantation, and the presence of DSA before transplantation determine the relative contribution to overall graft loss and the type of rejection involved.

Risk factors for renal allograft survival with China novel donation category: Donation after brain death followed by cardiac arrest

INTRODUCTION

To meet the need for transplantable organs, a new donation program was initiated by the Chinese government. This novel policy created three categories for deceased organ donations: donation after circulatory death cardiac death (DCD), donation after brain death (DBD), and donation after brain death followed by circulatory death (DBCD) meaning complete cardiac arrest. In fact, the DBCD method is a combination of both DBD and DCD methods. A DBCD donor meets the criteria of for brain death, but the organ procurement begins after the withdrawal of life support and the subsequent cardiac arrest death. The purpose of this study was to evaluate the long-term outcomes of kidney transplantation in our center with the DBCD policy. Potential risk factors for affecting the renal allograft survival were also analyzed based on our data.

METHOD

A retrospective study, involving 421 kidney transplants derived from 214 donors, was conducted between December 2011 and October 2019. In particular, 373 (88.6%) transplanted organs met the criteria for DBCD, and 48 (11.4%) for DCD. The log-rank test was used to compare the difference in survival. The Cox regression analysis was used for risk factor screening.

RESULT

Analysis showed that the DBCD group was better than the DCD group in terms of overall (p = 0.031) as well as death-censored (p = 0.026) allograft survival using the log-rank test. A Cox regression analysis revealed that increasing donor age (p = 0.002, HR = 1.820/10 years incremental older), increasing recipient age (p = 0.028, HR = 1.521/10 years increment older), prolonged dialysis duration (p = 0.007, HR = 1.018), occurrence episodes of acute rejection (p = 0.016, HR = 2.697), delayed graft function (p = 0.012, HR = 2.962), mismatch ≥4 HLA loci (p = 0.038, HR = 3.606), and warm ischemia time > 15 min (p = 0.022, HR = 2.915), were all independent risk factors affecting the graft survival.

CONCLUSION

The new DBCD policy of donation produced acceptable results similar or even better than the DCD practice. Based on our analysis, the graft survival of DBCD transplants may be better than DCD transplants. The main risk factors for allograft loss included an increasing donor age, recipient age, warm ischemia time > 15 min, prolonged dialysis duration, acute rejection, delayed graft function, and HLA mismatch ≥4 HLA loci.

Chimerism-Based Tolerance to Kidney Allografts in Humans: Novel Insights and Future Perspectives

Chronic rejection and immunosuppression-related toxicity severely affect long-term outcomes of kidney transplantation. The induction of transplantation tolerance – the lack of destructive immune responses to a transplanted organ in the absence of immunosuppression – could potentially overcome these limitations. Immune tolerance to kidney allografts from living donors has been successfully achieved in humans through clinical protocols based on chimerism induction with hematopoietic cell transplantation after non-myeloablative conditioning. Notably, two of these protocols have led to immune tolerance in a significant fraction of HLA-mismatched donor-recipient combinations, which represent the large majority of cases in clinical practice. Studies in mice and large animals have been critical in dissecting tolerance mechanisms and in selecting the most promising approaches for human translation. However, there are several key differences in tolerance induction between these models and humans, including the rate of success and stability of donor chimerism, as well as the relative contribution of different mechanisms in inducing donor-specific unresponsiveness. Kidney allograft tolerance achieved through durable full-donor chimerism may be due to central deletion of graft-reactive donor T cells, even though mechanistic data from patient series are lacking. On the other hand, immune tolerance attained with transient mixed chimerism-based protocols initially relies on Treg-mediated suppression, followed by peripheral deletion of donor-reactive recipient T-cell clones under antigenic pressure from the graft. These conclusions were supported by data deriving from novel high-throughput T-cell receptor sequencing approaches that allowed tracking of alloreactive repertoires over time. In this review, we summarize the most important mechanistic studies on tolerance induction with combined kidney-bone marrow transplantation in humans, discussing open issues that still need to be addressed and focusing on techniques developed in recent years to efficiently monitor the alloresponse in tolerance trials. These cutting-edge methods will be instrumental for the development of immune tolerance protocols with improved efficacy and to identify patients amenable to safe immunosuppression withdrawal.

Telemedicine monitoring in the follow-up of kidney transplant recipients: consensus indications from an Italian panel of surgeons and nephrologists after the COVID-19 experience

The quality of follow-up has clearly emerged as a key factor for long-term kidney graft survival. Currently, many clinics are facing difficulties in delivering optimal surveillance because of the increased number and complexity of kidney transplant recipients, and because of the COVID-19 pandemic. Additional ways of performing follow-up visits are needed and telemedicine has emerged as a tool to strengthen patient care intensity. Six Italian transplant surgeons and nephrologists convened via teleconference to develop a consensual model of video visits for the follow-up of kidney transplant recipients. Issues discussed were: profile of eligible patients; assessments that can be carried out; video visit organization and medical professionals involved; supporting tools and implementation. The video visit was consensually recognized as the most relevant for the follow-up of kidney transplant recipients. Eligible patients should have basic electronic devices and the skills to correctly use them and be in clinically stable condition. With the exception of physical and instrumental examination, and kidney biopsy, all other assessments are feasible during a video visit and can be implemented by specific training and use of supporting tools. The video visit model is simple and adaptable to most transplant patients. It is not intended to replace face-to-face examinations, but is an additional tool for improving the intensity of follow-up of kidney transplant recipients, which can be integrated into current monitoring protocols.

Organization of Post-Transplant Care and the 5-Year Outcomes of Kidney Transplantation

The outcomes of kidney transplantation depend on numerous factors and vary between transplant centers. The aim of this study is to assess the relationship between selected organizational factors, comorbidities, and patient and graft survival. This is a retrospective analysis of 438 renal transplant recipients (RTR) followed for 5 years. Patient and graft survival were evaluated in relation to hospitalization length, distance from the patient's residence to the transplant center, the frequency of outpatient transplant visits, and the number and type of comorbidities. Five-year patient and graft survival rates were 93% and 90%, respectively. We found significant associations of patient survival with the prevalence of pre-transplant diabetes, cardiovascular diseases, malignancies, the number of comorbidities, and the first post-transplant hospitalization length. The incidence of infections, cardiovascular diseases, and transplanted kidney diseases was 60%, 40%, and 33%, respectively. As many as 41% of RTR had unknown etiology of primary kidney disease. In conclusion, the organization of post-transplant care needs to be adapted to the multi-morbidity of contemporary RTR and include multi-specialist care, especially in the context of current problems related to the COVID-19pandemic. The high proportion of patients with undetermined etiology of their primary renal disease carry the risk for additional complications during their long-term follow-up.

Surfing the Big Data Wave: Omics Data Challenges in Transplantation

In both research and care, patients, caregivers, and researchers are facing a leap forward in the quantity of data that are available for analysis and interpretation, marking the daunting "big data era." In the biomedical field, this quantitative shift refers mostly to the -omics that permit measuring and analyzing biological features of the same type as a whole. Omics studies have greatly impacted transplantation research and highlighted their potential to better understand transplant outcomes. Some studies have emphasized the contribution of omics in developing personalized therapies to avoid graft loss. However, integrating omics data remains challenging in terms of analytical processes. These data come from multiple sources. Consequently, they may contain biases and systematic errors that can be mistaken for relevant biological information. Normalization methods and batch effects have been developed to tackle issues related to data quality and homogeneity. In addition, imputation methods handle data missingness. Importantly, the transplantation field represents a unique analytical context as the biological statistical unit is the donor-recipient pair, which brings additional complexity to the omics analyses. Strategies such as combined risk scores between 2 genomes taking into account genetic ancestry are emerging to better understand graft mechanisms and refine biological interpretations. The future omics will be based on integrative biology, considering the analysis of the system as a whole and no longer the study of a single characteristic. In this review, we summarize omics studies advances in transplantation and address the most challenging analytical issues regarding these approaches.

Detecting, preventing, and treating non-adherence to immunosuppression after kidney transplantation

Medication non-adherence (MNA) is a major issue in kidney transplantation and it is associated with increased risk of rejection, allograft loss, patients’ death and higher healthcare costs. Despite its crucial importance, it is still unclear what are the best strategies to diagnose, prevent and treat MNA. MNA can be intentional (deliberate refusal to take the medication as prescribed) or unintentional (non-deliberate missing the prescribed medication). Its diagnosis may rely on direct methods, aiming at measuring drug ingestions, or indirect methods that analyse the habits of patients to adhere to correct drug dose (taking adherence) and interval (time adherence). Identifying individual risk factors for MNA may provide the basis for a personalized approach to the treatment of MNA. Randomized control trials performed so far have tested a combination of strategies, such as enhancing medication adherence through the commitment of healthcare personnel involved in drug distribution, the use of electronic reminders, therapy simplification or various multidisciplinary approaches to maximize the correction of individual risk factors. Although most of these approaches reduced MNA in the short-term, the long-term effects on MNA and, more importantly, on clinical outcomes remain unclear. In this review, we provide a critical appraisal of traditional and newer methods for detecting, preventing and treating non-adherence to immunosuppression after kidney transplantation from the perspective of the practising physician.

Nutritional and dietary interventions to prolong renal allograft survival after kidney transplantation

PURPOSE OF REVIEW

Diet plays an important role in slowing progression of chronic kidney disease in native and transplanted kidneys. There is limited evidence on the association on dietary intake with renal allograft function. Mechanisms of major nutrients and dietary patterns with focusing on a plant-based diet related to kidney transplant health and longevity are reviewed.

RECENT FINDINGS

High dietary protein intake may adversely affect renal allograft. Low protein plant-focused diets such as Dietary Approaches to Stop Hypertension, plant-dominant low-protein diet and Mediterranean diets appear associated with favorable outcomes in slowing renal allograft function decline. The mechanism may be related to a change in renal hemodynamic by decreasing glomerular hyperfiltration from low dietary protein intake and plant-based ingredients. Recent observational studies of association between dietary protein intake and kidney allograft outcomes are conflicting. Although strong evidence is still lacking, a low protein diet of 0.6-0.8 g/kg/day with at least 50% of the protein source from plant-based components in kidney transplant recipients with stable kidney allograft function should be considered as the dietary target.

SUMMARY

Dietary intervention with low-protein plant-focused meals may improve outcomes in kidney transplant recipients, but the evidence remains limited and further studies are warranted.

Association of intraindividual tacrolimus variability with de novo donor-specific HLA antibody development and allograft rejection in pediatric kidney transplant recipients with low immunological risk

BACKGROUND

Tacrolimus (Tac) intraindividual variability (TacIPV) in pediatric kidney transplant patients is only poorly understood. We investigated the impact of TacIPV on de novo donor-specific HLA antibodies (dnDSA) development and allograft rejection in Caucasian pediatric recipients of a living or deceased donor kidney with low immunological risk.

METHODS

This was a single-center retrospective study including 48 pediatric kidney transplant recipients. TacIPV was calculated based on coefficient of variation (CV%) 6-12 months posttransplant. TacIPV cutoff was set at the median (25%). Outcome parameters were dnDSA development and rejection episodes.

RESULTS

In total, 566 Tac levels were measured with median 11.0 (6.0-17.0) measurements per patient. The cutoff of 25% corresponded to the median CV% in our study cohort (25%, IQR 18-35%) and was comparable to cutoffs determined by receiver operating characteristic (ROC) curve analysis. High TacIPV was associated with higher risk of dnDSA development (HR 3.4, 95% CI 1.0-11.1, P = 0.047; Kaplan-Meier analysis P = 0.018) and any kind of rejection episodes (HR 4.1, 95% CI 1.1-14.8, P = 0.033; Kaplan-Meier analysis P = 0.010). There was a clear trend towards higher TacIPV below the age of 6 years. TacIPV (CV%) was stable over time. A TacIPV (CV%) cutoff of 30% or IPV quantification by mean absolute deviation (MAD) showed comparable results.

CONCLUSIONS

High TacIPV is associated with an increased risk of dnDSA development and rejection episodes > year 1 posttransplant even in patients with low immunological risk profile. Therefore, in patients with high TacIPV, potential causes should be addressed, and if not resolved, changes in immunosuppressive therapy should be considered. A higher resolution version of the Graphical abstract is available as Supplementary information.

Urological Cancers and Kidney Transplantation: a Literature Review

PURPOSE OF REVIEW

The aim of this review is to provide an overview of epidemiology, risk factors, and treatment of urological malignancies in renal transplant recipients (RTR).

RECENT FINDINGS

Although optimal immunosuppressive therapy and cancer management in these patients remain controversial, adherence to general guidelines is recommended. Kidney transplantation is recognized as the standard of care for the treatment of end-stage renal disease (ESRD) as it offers prolonged survival and better quality of life. In the last decades, survival of RTRs has increased as a result of improved immunosuppressive therapy; nonetheless, the risk of developing cancer is higher among RTRs compared to the general population. Urological malignancies are the second most common after hematological cancer and often have more aggressive behavior and poor prognosis.

Pre-transplant donor-specific HLA antibodies and risk for poor first-year renal transplant outcomes: results from the Swiss Transplant Cohort Study

The aim of this study was to analyze first year renal outcomes in a nationwide prospective multicenter cohort comprising 2215 renal transplants, with a special emphasis on the presence of pre-transplant donor-specific HLA antibodies (DSA). All transplants had a complete virtual crossmatch and DSA were detected in 19% (411/2215). The investigated composite endpoint was a poor first-year outcome defined as (i) allograft failure or (ii) death or (iii) poor allograft function (eGFR ≤25 ml/min/1.73 m² ) at one year. Two hundred and twenty-one (221/2215; 10%) transplants showed a poor first-year outcome. Rejection (24/70; 34%) was the most common reason for graft failure. First-year patient's death was rare (48/2215; 2%). There were no statistically significant differences between DSA-positive and DSA-negative transplants regarding composite and each individual endpoint, as well as reasons for graft failure and death. DSA-positive transplants experienced more frequently rejection episodes, mainly antibody-mediated rejection (both P < 0.0001). The combination of DSA and any first year rejection was associated with the overall poorest death-censored allograft survival (P < 0.0001). In conclusion, presence of pre-transplant DSA per se does not affect first year outcomes. However, DSA-positive transplants experiencing first year rejection are a high-risk population for poor allograft survival and may benefit from intense clinical surveillance.

Does kidney transplantation with a standard or expanded criteria donor improve patient survival? Results from a Belgian cohort

BACKGROUND

Changes in recipient and donor factors have reopened the question of survival benefits of kidney transplantation versus dialysis.

METHODS

We analysed survival among 3808 adult Belgian patients waitlisted for a first deceased donor kidney transplant from 2000 to 2012. The primary outcome was mortality during the median waiting time plus 3 years of follow-up after transplantation or with continued dialysis. Outcomes were analysed separately for standard criteria donor (SCD) and expanded criteria donor (ECD) kidney transplants. We adjusted survival analyses for recipient age (20-44, 45-64 and ≥65 years), sex and diabetes as the primary renal disease.

RESULTS

Among patients ≥65 years of age, only SCD transplantation provided a significant survival benefit compared with dialysis, with a mortality of 16.3% [95% confidence interval (CI) 13.2-19.9] with SCD transplantation, 20.5% (95% CI 16.1-24.6) with ECD transplantation and 24.6% (95% CI 19.4-29.5) with continued dialysis. Relative mortality risk was increased in the first months after transplantation compared with dialysis, with equivalent risk levels reached earlier with SCD than ECD transplantation in all age groups.

CONCLUSIONS

The results of this study suggest that older patients might gain a survival benefit with SCD transplantation versus dialysis, but any survival benefit with ECD transplantation versus dialysis may be small.

Similar quality in chronic kidney disease multidisciplinary follow-up between kidney

INTRODUCTION

Multidisciplinary clinics are the best approach towards Chronic Kidney Disease (CKD) patients in pre-dialysis phases. The few studies regarding kidney transplant recipients (KTR) compare multidisciplinary and non-multidisciplinary clinics.

METHODS

In this study, we compared the quality of multidisciplinary CKD care between 101 KTR and 101 propensity score-matched non-transplant pre-dialysis patients (PDP). Prevalence of patients without specific treatment at any time and percent time without specific treatment for CKD complications were the main outcomes and patient and kidney function survival, glomerular filtration rate (GFR) decline, prevalence of CKD-related complications, and percent time within therapeutic goals were the exploratory ones.

RESULTS

Time within most goals was similar between the groups, except for diastolic blood pressure (83.4 vs. 77.3%, RR 0.92, CI 0.88-0.97, p = 0.002) and hypertriglyceridemia (67.7 vs. 58.2%, OR 0.85, CI 0.78-0.93, p < 0.001), better in non-transplant PDP, and for proteinuria (92.7 vs. 83.5%, RR 1.1, CI 1.05-1.16, p < 0.001), better in KTR. Patient survival and GFR decline were similar between the groups, although non-transplant PDP tended to progress earlier to dialysis (9.9% vs. 6.9%, HR 0.39, p = 0.07, CI 0.14-1.08).

DISCUSSION

The similar findings between non-transplant PDP and KTR suggests that good and comparable quality of multidisciplinary is a valid strategy for promoting optimal clinical management of CKD-related complications in KTR.

Metabolic Consequences of Solid Organ Transplantation

Metabolic complications affect over 50% of solid organ transplant recipients. These include posttransplant diabetes, nonalcoholic fatty liver disease, dyslipidemia, and obesity. Preexisting metabolic disease is further exacerbated with immunosuppression and posttransplant weight gain. Patients transition from a state of cachexia induced by end-organ disease to a pro-anabolic state after transplant due to weight gain, sedentary lifestyle, and suboptimal dietary habits in the setting of immunosuppression. Specific immunosuppressants have different metabolic effects, although all the foundation/maintenance immunosuppressants (calcineurin inhibitors, mTOR inhibitors) increase the risk of metabolic disease. In this comprehensive review, we summarize the emerging knowledge of the molecular pathogenesis of these different metabolic complications, and the potential genetic contribution (recipient +/- donor) to these conditions. These metabolic complications impact both graft and patient survival, particularly increasing the risk of cardiovascular and cancer-associated mortality. The current evidence for prevention and therapeutic management of posttransplant metabolic conditions is provided while highlighting gaps for future avenues in translational research.