Adult Living-Donor Kidney Transplantation, Donor Age, and Donor-Recipient Age

Comparison of Kidney Graft Function and Survival in an Emulated Trial With Living Donors and Brain-Dead Donors

Living donation (LD) transplantation is the preferred treatment for kidney failure as compared to donation after brain death (DBD), but age may play a role. We compared the 1-year estimated glomerular filtration rate (eGFR) after kidney transplantation for recipients of LD and DBD stratified by recipient and donor age between 2015 and 2018 in a matched cohort. The strength of the association between donation type and 1-year eGFR differed by recipient age (P interaction < 0.0001). For LD recipients aged 40-54 years versus same-aged DBD recipients, the adjusted odds ratio (aOR) for eGFR ≥60 mL/min/1.73 m2 was 1.48 (95% CI: 1.16-1.90). For DBD recipients aged ≥ 60 years, the aOR was 0.18 (95% CI: 0.12-0.29) versus DBD recipients aged 40-54 years but was 0.91 (95% CI: 0.67-1.24) versus LD recipients aged ≥60 years. In the matched cohort, 4-year graft and patient survival differed by donor age and type. As compared with DBD grafts, LD grafts increased the proportion of recipients with 1-year eGFR ≥60 mL/min/1.73 m2. Recipients aged ≥60 years benefited most from LD transplantation, even if the donor was aged ≥60 years. For younger recipients, large age differences between donor and recipient could also be addressed with a paired exchange program.

Analysis of IL-17A, IL-17F, and miR-146a-5p Prior to Transplantation and Their Role in Kidney Transplant Recipients

Background/Objectives: The balance between regulatory and Th17 cells plays an important role in maintaining the immune tolerance after kidney transplantation (KTx) which is essential for transplantation success, defined as a long graft survival and an absence of organ rejection. The present study aimed to assess whether the pretransplant characteristics of IL-17A and IL-17F, their receptors, as well as miR-146a-5p, an miRNA associated with IL-17A/F regulation, can predict KTx outcomes. Methods: A group of 108 pre-KTx dialysis patients and 125 healthy controls were investigated for single nucleotide substitutions within genes coding for IL-17A, IL-17F, their IL-17RA/RC receptors, and miR-146a-5p. Genotyping was performed using LightSNiP assays. In addition, IL17-A/F serum concentrations were determined using ELISA while miR-146a-5p expression was analyzed by RT-PCR. Results: The IL-17F (rs763780) G allele prevailed in KTx recipients as compared to healthy individuals (OR = 23.59, p < 0.0001) and was associated with a higher IL-17F serum level (p = 0.0381) prior to transplantation. Higher miR-146a-5p expression before KTx was more frequently detected in recipients with an increased IL-17A serum concentration (p = 0.0177). Moreover, IL-17A (rs2275913) GG homozygosity was found to be associated with an increased incidence of deaths before KTx (OR = 4.17, p = 0.0307). T-cell or acute rejection episodes were more frequently observed among patients with the C allele of miR-146a-5p (rs2910164) (OR = 5.38, p = 0.0531). IL17-RA/-RC genetic variants (p < 0.05) seem to be associated with eGFR values. Conclusions: These results imply that IL-17F (rs763780) polymorphism is associated with the serum level of this cytokine and may be related to the risk of renal disease and transplant rejection together with miR-146a-5p (rs2910164), while the IL-17A (rs2275913) genotype may affect patients' survival before KTx.

Impact of Age 70 years or Older on Donors for Living-Donor Kidney Transplantation

Introduction

Kidney transplantation (KT) involving elderly living kidney donors (LKDs) is becoming more frequent because of a profound organ shortage. The efficacy of KT involving grafts obtained from LKDs aged 70 years or older has been reported. However, the safety of donor nephrectomy in LKDs aged 70 years or older, including that associated with changes in the estimated glomerular filtration rate (eGFR), has not been investigated. This study investigated the outcomes of LKDs aged 70 years or older after donor nephrectomy.

Methods

This single-center, retrospective cohort study included 1226 LKDs who underwent donor nephrectomy between January 2008 and December 2020. LKDs were stratified into the following age groups: 30 to 49 years (244 LKDs), 50 to 69 years (803 LKDs), and 70 to 89 years (179 LKDs). Surgical outcomes, postoperative eGFR changes, end-stage renal disease (ESRD) rates, and mortality rates were compared among these groups.

Results

No significant difference in surgical outcomes was identified among the groups. LKDs aged 70 to 89 years experienced the lowest eGFR changes at all time points and the lowest eGFR improvement; however, ESRD was not identified in any group during the observation period. Mortality was the highest among LKDs aged 70 to 89 years compared to the other age groups.

Conclusion

Surgical outcomes, eGFR changes, and ESRD incidences can support the safety of donor nephrectomy in LKDs aged 70 years or older. Considering the advanced age, the high mortality rates in LKDs aged 70 years or older could be considered acceptable.

Survival Advantage Comparing Older Living Donor Versus Standard Criteria Donor Kidney Transplants

The aim of this analysis was to explore mortality outcomes for kidney transplant candidates receiving older living donor kidneys (age ≥60 years) versus younger deceased donors or remaining on dialysis. From 2000 to 2019, all patients on dialysis listed for their first kidney-alone transplant were included in a retrospective cohort analysis of UK transplant registry data. The primary outcome was all-cause mortality, with survival analysis conducted by intention-to-treat principle. Time-to-death from listing was modelled using nonproportional hazard Cox regression models with transplantation handled as a time-dependent covariate. A total of 32,978 waitlisted kidney failure patients formed the primary study cohort, of whom 18,796 (58.5%) received a kidney transplant (1,557 older living donor kidneys and 18,062 standard criteria donor kidneys). Older living donor kidney transplantation constituted only 17.0% of all living donor kidney transplant activity (overall cohort; n = 9,140). Recipients of older living donor kidneys had reduced all-cause mortality compared to receiving SCD kidneys (HR 0.904, 95% CI 0.845-0.967, p = 0.003) and much lower all-cause mortality versus remaining on the waiting list (HR 0.160, 95% CI 0.149-0.172, p < 0.001). Older living kidney donors should be actively explored to expand the living donor kidney pool and are an excellent treatment option for waitlisted kidney transplant candidates.

Prediction models for the recipients' ideal perioperative estimated glomerular filtration rates for predicting graft survival after adult living-donor kidney transplantation

Introduction

The impact of the perioperative estimated glomerular filtration rate (eGFR) on graft survival in kidney transplant recipients is yet to be evaluated. In this study, we developed prediction models for the ideal perioperative eGFRs in recipients.

Methods

We evaluated the impact of perioperative predicted ideal and actual eGFRs on graft survival by including 1,174 consecutive adult patients who underwent living-donor kidney transplantation (LDKT) between January 2008 and December 2020. Prediction models for the ideal perioperative eGFR were developed for 676 recipients who were randomly assigned to the training and validation sets (ratio: 7:3). The prediction models for the ideal best eGFR within 3 weeks and those at 1, 2, and 3 weeks after LDKT in 474 recipients were developed using 10-fold validation and stepwise multiple regression model analyzes. The developed prediction models were validated in 202 recipients. Finally, the impact of perioperative predicted ideal eGFRs/actual eGFRs on graft survival was investigated using Fine-Gray regression analysis.

Results

The correlation coefficients of the predicted ideal best eGFR within 3 weeks and the predicted ideal eGFRs at 1, 2, and 3 weeks after LDKT were 0.651, 0.600, 0.598, and 0.617, respectively. Multivariate analyzes for graft loss demonstrated significant differences in the predicted ideal best eGFR/actual best eGFR within 3 weeks and the predicted ideal eGFRs/actual eGFRs at 1, 2, and 3 weeks after LDKT.

Discussion

The predicted ideal best eGFR/actual best eGFR within 3 weeks and the predicted ideal eGFRs/actual eGFRs at 1, 2, and 3 weeks after LDKT were independent prognostic factors for graft loss. Therefore, the perioperative predicted ideal eGFR/actual eGFR may be useful for predicting graft survival after adult LDKT.

Donor Evaluation of Living Kidney Transplantation in the Aging Society

BACKGROUND

Because of the lack of organ donation, living kidney transplantation (LKT) is increasing worldwide. Recently, the number of elderly donors has been increasing, and the patients with end-stage kidney diseases are older than those in the previous decades. Due to the advanced ages, their glomerular filtration rates (GFR) decrease, and the comorbidities such as hypertension, diabetic condition, and obesity are common. The clinicians now have to give their unwilling consent to the LKT from the donors with expanded criteria.

SUMMARY

For the secure selection of donors, proper GFR measuring is essential. Although directly measured GFR (mGFR) was recommended in the guidelines, estimated GFR (eGFR) is used at the initial evaluation of donor renal function clinically. Many equations calculating eGFR have been published so far. In the selection of eGFR equations, the smaller difference between mGFR and eGFR and the closer relationship to the prevalence rates of comorbidities are requisite points. Therefore, we compared the specificity of the various eGFR equations. The eGFR calculated from the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation showed approximate reliability with minimal difference between mGFR and eGFR and the closer relationships to the prevalence rates of comorbidities.

KEY MESSAGE

The CKD-EPI-eGFR presented optimal performance in the donor renal function evaluation. Therefore, eGFR from the CKD-EPI equation is highly recommended in evaluating renal function in LKT donors.

Risk Factors of Rejection in Renal Transplant Recipients: A Narrative Review

Multiple factors influence graft rejection after kidney transplantation. Pre-operative factors affecting graft function and survival include donor and recipient characteristics such as age, gender, race, and immunologic compatibility. In addition, several peri- and post-operative parameters affect graft function and rejection, such as cold and warm ischemia times, and post-operative immunosuppressive treatment. Exposure to non-self-human leucocyte antigens (HLAs) prior to transplantation up-regulates the recipient’s immune system. A higher rate of acute rejection is observed in transplant recipients with a history of pregnancies or significant exposure to blood products because these patients have higher panel reactive antibody (PRA) levels. Identifying these risk factors will help physicians to reduce the risk of allograft rejection, thereby promoting graft survival. In the current review, we summarize the existing literature on donor- and recipient-related risk factors of graft rejection and graft loss following kidney transplantation.