Elderly living donor kidney transplantation allows worthwhile outcomes: The Japan Academic Consortium of Kidney Transplantation study

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.

Long-term prolonged-release tacrolimus outcomes in living donor kidney transplantation: The Japan Academic Consortium of Kidney Transplantation study-II

OBJECTIVES

To evaluate the 10-year efficacy and safety of a prolonged-release tacrolimus-based combination immunosuppressive regimen on longer-term outcomes in living donor kidney transplantation.

METHODS

Data from Japanese living donor kidney transplant recipients (n = 410) maintained on continuous prolonged-release tacrolimus-based immunosuppression from 2009-2013 were analyzed with a median follow-up of 9.9 years.

RESULTS

A prolonged-release, tacrolimus-based combination regimen provided death-censored graft failure and all-cause death rates at 10 years of 7.0% and 6.8%, respectively. In multivariable analyses, acute and chronic rejection and 'throughout' (new-onset plus preexisting) diabetes mellitus were risk factors for death-censored graft failure. Recipient age ≥ 65 years, throughout diabetes mellitus and malignancy were common risk factors for all-cause death. Throughout diabetes mellitus was the most common risk factor for both death-censored graft failure and all-cause death. Additional analyses showed 10-year cumulative rates of death-censored graft failure were 14.0% and 5.4% for recipients with or without preexisting diabetes mellitus, respectively (log-rank test: p = 0.009). All-cause death rates were 12.7% and 5.4% in the preexisting and non-diabetes mellitus groups, respectively (log-rank test: p = 0.023).

CONCLUSIONS

In this real-world, retrospective, living donor kidney transplantation study, a prolonged-release tacrolimus-based immunosuppressive combination regimen provided 10-year death-censored graft failure rates of 14.0% and 5.4% in diabetes mellitus and non-diabetes mellitus patients, respectively; Similarly, 10-year all-cause death rates were 12.7% and 5.4% in diabetes mellitus and non-diabetes mellitus patients, respectively. To our knowledge, the data in this study are the first to provide 10-year transplant outcomes in living donor kidney transplant recipients under prolonged-release tacrolimus-based regimen.

Older Age is Associated With Lower Utilization of Living Donor Kidney Transplant

Introduction

Older adults (65 years or older) constitute a substantial and increasing proportion of patients with kidney failure, potentially needing kidney replacement therapy. Living donor kidney transplant (LDKT) offers superior outcomes for suitable patients of all ages. However, exploring LDKT and finding a living donor could be challenging for older adults. Here, we assessed the association between age and utilization of LDKT and assessed effect modification of key variables such as ethnicity and language.

Methods

This is a retrospective cohort study of patients with kidney failure referred for kidney transplant (KT) assessment in Toronto between January 2006 and December 2013. The association between age and having a potential living donor identified was assessed using logistic regression and the association between age and the receipt of LDKT was assessed using Cox proportional hazards models.

Results

Of the 1617 participants, 50% were middle-aged (45-64 years old), and 17% were ≥65 years old. In our final multivariable adjusted models, compared to young adults, middle-aged and older adults had lower odds of having a potential living donor identified (odds ratio [OR], 0.47; confidence interval [CI], [0.35-0.63]; OR, 0.30; CI, [0.20-0.43]; P < 0.001, for middle-aged and older adults, respectively), and were less likely to receive LDKT (hazard ratio [HR], 0.79; CI, [0.63-0.99]; P = 0.04; HR, 0.47; CI, [0.30-0.72]; P = 0.001, for middle-aged and older adults, respectively.).

Conclusion

Age is an independent predictor of receiving LDKT. Considering that nearly 90% of patients with kidney failure in Canada are >45 years of age, these results point to important and potentially modifiable age-related barriers to LDKT.

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

INTRODUCTION

Owing to organ shortage, the number of kidney transplantation (KT) involving older adult living donors is increasing. We aimed to investigate the effects of living-donor age and donor-recipient age differences on KT outcomes.

METHODS

This single-center, retrospective cohort study involved 853 adult LDKTs performed between January 2008 and December 2018. Recipients were stratified into the following 5 groups based on donor age and donor-recipient age difference: donor age, 30 to 49 years and age difference, -10 to 15 years; donor age, 50 to 69 years and age difference, -10 to 15 years; donor age, 50 to 69 years and age difference, 15 to 40 years; donor age, 70 to 89 years and age difference, -10 to 15 years; and donor age, 70 to 89 years and age difference, 15 to 40 years (groups 1, 2, 3, 4, and 5, respectively). As a primary outcome, the risk of graft loss was investigated. The secondary outcomes were postoperative estimated glomerular filtration rates (eGFRs) and mortality rates of recipients.

RESULTS

Group 4, representing KT between older adult donors and older adult recipients, had the highest graft loss risk and mortality. The eGFRs of the recipients from donors aged 70 to 89 years (groups 4 and 5) were significantly lower than those from donors in the other groups. Although the differences in the eGFR between groups 4 and 5 were not significant, the eGFR of group 4 was lower than that of group 5 at 6 months post-KT.

CONCLUSION

LDKTs from older adult donors to older adult recipients resulted in the worst graft survival and mortality rates.

Kidney Transplant Outcomes in elderly Recipients: An Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry Study

BACKGROUND

There is an increase in elderly patients receiving kidney transplant internationally. This study describes elderly kidney transplant recipient outcomes in Australia and New Zealand.

METHODS

The study included all adult first kidney transplant recipients in Australia and New Zealand from 2000 to 2015. Survival and graft outcomes were compared between elderly (≥70 years) and younger (18-69 years) recipients using Cox proportional hazards regression.

RESULTS

Overall, 10651 kidney transplant recipients were included, of which 279 (2.6%) were elderly adults. The proportion of elderly recipients increased from 0.6 to 4.4% from 2000 to 2015. Compared with younger recipients, elderly recipients were more likely to receive kidneys from deceased donors, elderly donors, and expanded criteria donors. Elderly recipients experienced poorer patient survival with 1- and 5-year survival ranging from 96% to 97% and 79% to 81%, respectively, compared with 97% to 99% and 90% 95% in younger recipients, respectively. Elderly recipients experienced comparable rates of delayed graft function and, in living donor kidney recipients, lower rates of acute rejection.

CONCLUSIONS

Kidney transplantation in the elderly population is increasing. Although elderly recipients had inferior survival and graft outcomes, elderly recipients generally received poorer quality kidneys. The outcomes achieved in this cohort of elderly adults are encouraging, and improving elderly recipient outcomes should be an important focus for research.

Serum N-glycan profiling can predict biopsy-proven graft rejection after living kidney transplantation

BACKGROUND

To evaluate whether serum N-glycan profile can be used as a diagnostic marker of graft rejection after living-donor kidney transplants (KT).

METHODS

We retrospectively examined 174 KT recipients at five medical centers. N-Glycan levels were analyzed in postoperative serum samples using glycoblotting combined with mass spectrometry. We developed an integrated score to predict graft rejection based on a combination of age, gender, immunological risk factors, and serum N-glycan levels at post-KT day D1 and D7. Rejection-free survival rates stratified by the sum of integrated scores (D1 + D7) were evaluated using Kaplan-Meier curves.

RESULTS

Of 174, 52 showed graft rejection (Rejection-pos. group) and 122 recipients did not show graft rejection (Rejection-neg. group). The integrated scores were significantly higher in the Rejection-pos. group than those of the Rejection-neg. group. Area-under-curve (AUC) value of integrated scores at post-KT D1, and D7 were 0.84 and 0.84, respectively. The sum of integrated scores (D1 + D7) ≥ 0.50 identified graft rejection with 81% sensitivity and 80% specificity; with an AUC value of 0.87. Recipients with higher sum of integrated scores (D1 + D7 ≥ 0.5) had significantly shorter rejection-free survival than those with lower scores.

CONCLUSION

Evaluation of serum N-glycosylation profiles can identify recipients who are prone to rejection.

Development and validation of a new prediction model for graft function using preoperative marginal factors in living-donor kidney transplantation

BACKGROUND

Recently, living-donor kidney transplantation from marginal donors has been increasing. However, a simple prediction model for graft function including preoperative marginal factors is limited. Here, we developed and validated a new prediction model for graft function using preoperative marginal factors in living-donor kidney transplantation.

METHODS

We retrospectively investigated 343 patients who underwent living-donor kidney transplantation at Kyushu University Hospital (derivation cohort). Low graft function was defined as an estimated glomerular filtration rate of < 45 mL/min/1.73 m² at 1 year. A prediction model was developed using a multivariable logistic regression model, and verified using data from 232 patients who underwent living-donor kidney transplantation at Tokyo Women's Medical University Hospital (validation cohort).

RESULTS

In the derivation cohort, 89 patients (25.9%) had low graft function at 1 year. Donor age, donor-estimated glomerular filtration rate, donor hypertension, and donor/recipient body weight ratio were selected as predictive factors. This model demonstrated modest discrimination (c-statistic = 0.77) and calibration (Hosmer-Lemeshow test, P = 0.83). Furthermore, this model demonstrated good discrimination (c-statistic = 0.76) and calibration (Hosmer-Lemeshow test, P = 0.54) in the validation cohort. Furthermore, donor age, donor-estimated glomerular filtration rate, and donor hypertension were strongly associated with glomerulosclerosis and atherosclerotic vascular changes in the "zero-time" biopsy.

CONCLUSIONS

This model using four pre-operative variables will be a simple, but useful guide to estimate graft function at 1 year after kidney transplantation, especially in marginal donors, in the clinical setting.

The interaction between post-transplant anemia and allograft function in kidney transplantation: The Japan Academic Consortium of Kidney Transplantation-II study

BACKGROUND

The interaction between post-transplant anemia (PTA) and allograft function in kidney transplantation has not been evaluated directly. PTA, defined by WHO/AST criteria, was investigated in 1307 adult kidney transplant recipients between 2000 and 2015 (median follow-up, 7 years).

METHODS

We investigated the impact of hemoglobin (Hb) on graft failure (non-censored for death) and their interactions, time-dependent Cox model, and subgroup analysis were used.

RESULTS

PTA prevalence was 43.6% at 7 years and varied according to allograft function, recipient sex, and follow-up period. Decreased Hb considering the time-varying effect was associated with an increased risk of graft failure (hazard ratio = 1.83, 95% CI 1.66-2.02, P < 0.001). In subgroup analysis, allograft function (post-transplant time-averaged estimated glomerular filtration rate and cut point: 45 mL/min/1.73 m²) had significant interaction (P = 0.032). The 7-year graft failure rate in recipients with PTA and high eGFR was 7.7% (HR 1.52, 95% CI 1.25-1.84), whereas in those with PTA and low eGFR was 19.9% (HR 2.00, 95% CI 1.74-2.31).

CONCLUSIONS

The unfavorable impact of PTA was significantly enhanced by low allograft function. PTA is likely to be associated with graft failure due to interaction with allograft function. Therefore, we should consider both Hb level and allograft function while determining the treatment strategy.

Impact of distance between donor and recipient hospitals on cadaveric kidney transplantation outcomes

BACKGROUND

The impact of distance between donor and recipient hospitals on outcomes in cadaveric kidney transplantations is unknown. We investigated the association between inter-hospital distance and outcomes in cadaveric kidney transplantations in Japan.

METHODS

We retrospectively analyzed 363 cadaveric kidney transplantations between 2002 and 2017 in Japan. Inter-hospital distance, graft transport time, total ischemic time (TIT), and graft survival were compared between our hospital and national transplantation cohort in Japan. Estimated glomerular filtration rate (eGFR) 1 month and 1 year after transplantation was compared between cadaveric and living-donor kidney transplantations in our hospitals. Additionally, inter-hospital distances among the seven geographical regions in Japan were assessed.

RESULTS

There were 12 and 351 cadaveric kidney transplantations at our hospital and in Japan, respectively. Mean inter-hospital distance at our hospital (217 ± 121 km) was significantly longer than that of the national cohort (53 ± 80 km; P < 0.001). Mean TIT and graft survival for our hospital and national cohort were 539 ± 200 min and 91% and 491 ± 193 min and 81%, respectively. Mean eGFRs 1 year after cadaveric and living-donor transplantations at our hospitals were comparable (47 ± 16 vs. 47 ± 15 mL/min/1.73 m²). The comparison among seven regions in Japan indicated a regional difference in inter-hospital distance with an association between area (km²) and inter-hospital distance (km).

CONCLUSIONS

Despite the longer inter-hospital distance at our hospital, TIT and transplant outcomes were acceptable in our cases. In addition, geographical inequity in graft allocation in Japan was suggested.

Causes of Ineligibility for Recipients in Living Kidney Transplantation

BACKGROUND

Even if a living donor candidate exists, there are some cases that do not result in kidney transplantation (KTx) due to problems on the recipient side. The aim of this study was to clarify causes of ineligibility for KTx in these cases, so as to make RTx more applicable for patients.

METHODS

We targeted 470 patients with end-stage renal disease who applied for the primary kidney KTx from 2010 to 2012. Then we selected those who were not applicable for KTx and investigated recipient causes of ineligibility for KTx or not receiving KTx.

RESULTS

The average age of recipients was 47.6 ± 12.9 (7-82) years. A majority of the 470 patients were male (n = 305, 64.9%). Two hundred ninety-seven patients intended to receive a living donor KTx and the others hoped for a deceased donor KTx. Of the 297 patients, 207 (70.0%) underwent KTx and 9 (1.9%) were being prepared for KTx at the time of the survey. Eighty-three patients (27.9%) did not receive a living KTx, with 59 of these due to recipient-related problems and 30 due to donor-related problems. We further classified the reasons for these 59 recipients not undergoing KTx as follows: (1) unclear reasons (35.6%); (2) insufficient intention to receive transplant (13.6%); (3) heart disease (10.2%); (4) malignancy (8.5%); (5) immunologic risks (5.1%); (6) death during the waiting period (5.1%); (7) cerebrovascular events (5.1%); (8) cardiovascular problems (5.1%); (9) psychiatric disorders (3.4%); and (10) infections (3.4%).

CONCLUSION

Nearly 50% of the reasons for ineligibility as a recipient were related to their intention to receive KTx, with 94.9% of the nontransplanted cases due to nonimmunologic reasons. Thanks to the recent advances in immunosuppressive therapy, there were only 3 patients who could not undergo KTx due to immunologic risks. Based on these results, transplant surgeons should not only emphasize physical evaluation but should also pay careful attention to the recipient's intention to receive KTx.