Age-matching in renal transplantation

Maximizing opportunities for kidney transplantation in older adults

PURPOSE OF REVIEW

To summarize the current state of evidence related to the outcomes of older adults who need and receive kidney transplants, and strategies to facilitate appropriate transplant access in this at-risk group.

RECENT FINDINGS

Older adults are a rapidly growing subgroup of the kidney transplant waitlist. Compared to younger adults, older kidney transplant recipients have increased mortality after kidney transplant and lower death-censored graft survival. In determining suitability for transplantation in older patients, clinicians must balance procedural and immunosuppression-related risk with incremental survival when compared with dialysis. To appropriately increase access to transplantation in this population, clinicians and policy makers consider candidates' chronological age and frailty, as well as the quality of and waiting time for a donated allograft. Given risk of deterioration prior to transplant, candidates should be rapidly evaluated, listed, and transplanted using living donor and or less than ideal deceased donor organs when available.

SUMMARY

Access to transplantation for older adults can be increased through targeted interventions to address frailty and reduce waiting times through optimized organ use. Focused study and educational interventions for patients and providers are needed to improve the outcomes of this vulnerable group.

SPIKE: secure and private investigation of the kidney exchange problem

BACKGROUND

The kidney exchange problem (KEP) addresses the matching of patients in need for a replacement organ with compatible living donors. Ideally many medical institutions should participate in a matching program to increase the chance for successful matches. However, to fulfill legal requirements current systems use complicated policy-based data protection mechanisms that effectively exclude smaller medical facilities to participate. Employing secure multi-party computation (MPC) techniques provides a technical way to satisfy data protection requirements for highly sensitive personal health information while simultaneously reducing the regulatory burdens.

RESULTS

We have designed, implemented, and benchmarked SPIKE, a secure MPC-based privacy-preserving KEP protocol which computes a locally optimal solution by finding matching donor-recipient pairs in a graph structure. SPIKE matches 40 pairs in cycles of length 2 in less than 4 min and outperforms the previous state-of-the-art protocol by a factor of [Formula: see text] in runtime while providing medically more robust solutions.

CONCLUSIONS

We show how to solve the KEP in a robust and privacy-preserving manner achieving significantly more practical performance than the current state-of-the-art (Breuer et al., WPES'20 and CODASPY'22). The usage of MPC techniques fulfills many data protection requirements on a technical level, allowing smaller health care providers to directly participate in a kidney exchange with reduced legal processes. As sensitive data are not leaving the institutions' network boundaries, the patient data underlie a higher level of protection than in the currently employed (centralized) systems. Furthermore, due to reduced legal barriers, the proposed decentralized system might be simpler to implement in a transnational, intereuropean setting with mixed (national) data protecion laws.

Donor-Recipient Matching in Kidney Transplant: We're Not There Yet

BACKGROUND

Strategic organ allocation is expected to prolong patient and graft survival after transplant. This study explored differences in graft survival when kidneys are allocated based on strategic donor-recipient (D-R) pairing vs with the existing Kidney Allocation System (KAS).

METHODS

Using the Scientific Registry of Transplant Recipients from 2000 to 2014, we used a multivariable Cox model to assess the hazard ratios (HRs) for death or graft failure among 3 hypothetical donor kidneys transplanted into 3 hypothetical recipients, relative to an ideally matched D-R pair. Median predicted survival for each of the 9 possible D-R pairing combinations was determined, and outcomes for strategic D-R pairing were compared with those obtained using the KAS for allocation.

RESULTS

A total of 31,607 patients (29.7%) died or developed graft loss over the study period. Strategic allocation of kidneys resulted in HRs for graft loss of 1.74 (95% confidence interval [CI], 1.41-2.14), 1.82 (95% CI, 1.46-2.26), and 1.74 (95% CI 1.38-2.19) for recipients 1, 2 and 3 respectively, whereas by following the KAS, HRs were 1.93 (95%, CI 1.63-2.28), 2.06 (95% CI, 1.74-2.44), and 1.93 (95% CI, 1.58-2.37); corresponding to 3.84, 11.39, and 7.40 months longer predicted patient or graft survival for recipients 1, 2 and 3 with strategic D-R pairing compared with the KAS.

CONCLUSIONS

Allocation of kidneys by strategic D-R pairing may improve graft survival relative to allocation using the KAS.

Hepatitis C-positive donor to negative recipient kidney transplantation: A real-world experience

BACKGROUND

Several studies have shown that transplanting a hepatitis C virus (HCV)-negative recipients with a HCV-positive donor is feasible in a research setting. In February 2018, we began transplanting HCV-negative recipients with HCV-positive donors as standard of care.

METHODS

All patients, except those with previously cured HCV and those with cirrhosis, were consented for HCV NAT-positive donor kidneys. After transplantation, patients were tested for HCV RNA until viremic. A direct-acting antiviral (DAA) agent was prescribed based on genotype and insurance approval. Sustained virologic response (SVR) at weeks 4 and 12 was recorded. Renal function and death censored graft survival at 1 year were evaluated and compared to recipients of HCV NAT-negative kidneys.

RESULTS

A total of 25 HCV NAT-positive donor kidney transplants from February to October 2018 were performed. All patients received basiliximab and maintained with tacrolimus, mycophenolate mofetil, and prednisone. Median time from viremia to start of DAA was 13 (8-22) days. The most common genotype was 1a (60%), followed by 3a (28%). The most commonly prescribed DAA was ledipasvir/sofosbuvir (56%), followed by velpatasvir/sofosbuvir (32%), and then glecaprevir/pibrentasvir (12%). All patients achieved initial SVR12, except one. One patient had a mixed-genotype infection requiring retreatment to achieve SVR12. Death censored graft survival was 96%. Recipients of HCV NAT-positive organs compared to HCV NAT-negative organs received younger donors (mean 35 ± 8.9 vs 45.1 ± 15.7 years; P < .01) and spent less time on the waitlist (median 479 (93-582) vs 1808 (567-2263) days; P = .02).

CONCLUSION

HCV NAT-negative recipients can be safely and successfully transplanted with HCV NAT-positive donor kidneys outside of a research protocol. Access to DAA and timely administration of therapy is important and an insurance approval process within the transplant center can be beneficial to patients. A case of mixed-genotype infection was presented, and although not as common, can be successfully treated. HCV organs can expand the organ pool and should no longer be considered experimental. The use of these organs in HCV-negative recipient's decreases waiting time, have excellent outcomes, and should be considered standard of care.

Kidney transplantation in the extremely elderly from extremely aged deceased donors: a kidney for each age

BACKGROUND

Advances in life expectancy have led to an increase in the number of elderly people with end-stage renal disease (ESRD). Scarce information is available on the outcomes of kidney transplantation (KT) in extremely elderly patients based on an allocation policy prioritizing donor-recipient age matching.

METHODS

We included recipients ≥75 years that underwent KT from similarly aged deceased donors at our institution between 2002 and 2015. Determinants of death-censored graft and patient survival were assessed by Cox regression.

RESULTS

We included 138 recipients with a median follow-up of 38.8 months. Median (interquartile range) age of recipients and donors was 77.5 (76.3-79.7) and 77.0 years (74.7-79.0), with 22.5% of donors ≥80 years. Primary graft non-function occurred in 8.0% (11/138) of patients. Cumulative incidence rates for post-transplant infection and biopsy-proven acute rejection (BPAR) were 70.3% (97/138) and 15.2% (21/138), respectively. One- and 5-year patient survival were 82.1 and 60.1%, respectively, whereas the corresponding rates for death-censored graft survival were 95.6 and 93.1%. Infection was the leading cause of death (46.0% of fatal cases). The occurrence of BPAR was associated with lower 1-year patient survival [hazard ratio (HR) = 4.21, 95% confidence interval (CI) 1.64-10.82; P = 0.003]. Diabetic nephropathy was the only factor predicting 5-year death-censored graft survival (HR = 4.82, 95% CI 1.08-21.56; P = 0.040).

CONCLUSIONS

ESRD patients ≥75 years can access KT and remain dialysis free for their remaining lifespan by using grafts from extremely aged deceased donors, yielding encouraging results in terms of recipient and graft survival.

Young deceased donor kidneys show a survival benefit over older donor kidneys in transplant recipients aged 20-50 years: a study by the ERA-EDTA Registry

BACKGROUND

Updated survival outcomes of young recipients receiving young or old deceased donor kidneys are required when considering accepting a deceased donor kidney.

METHODS

We examined outcomes in 6448 European kidney allografts donated from younger (≥20-<50 years) and older (≥50-<70 years) deceased donors when transplanted into very young (≥20-<35 years) or young (≥35-<50 years) adult recipients. Outcomes of first kidney transplantations during 2000-13 and followed-up to 2015 were determined via competing risk, restricted mean survival and Cox regression methods.

RESULTS

The 10-year cumulative incidence of graft failure was lowest in very young {22.0% [95% confidence interval (95% CI) 19.1-24.9]} and young [15.3% (95% CI 13.7-16.9)] recipients of younger donor kidneys and highest in very young [36.7% (95% CI 31.9-41.5)] and young [29.2% (95% CI 25.1-33.2)] recipients of older donor kidneys. At the 10-year follow-up, younger donor kidneys had a 1 year (very young) or 9 months (young) longer mean graft survival time compared with older donor kidneys. Graft failure risk in younger donor kidneys was 45% [very young adjusted hazard ratio (aHR) 0.55 (95% CI 0.44-0.68)] and 40% [young aHR 0.60 (95% CI 0.53-0.67)] lower compared with older donor kidneys. A 1-year increase in donor age resulted in a 2% [very young aHR 1.02 (95% CI 1.00-1.04)] or 1% [young aHR 1.01 (95% CI 1.00-1.01)] increase in the 10-year risk of death.

CONCLUSIONS

Younger donor kidneys show survival benefits over older donor kidneys in adult recipients ages 20-50 years. Updated survival outcomes from older deceased donors are necessary due to advances in transplantation medicine and the increasing role these donors play in organ transplantation.

Impact of Combinations of Donor and Recipient Ages and Other Factors on Kidney Graft Outcomes

As the availability of kidneys for transplantation continues to be outpaced by its growing demand, there has been an increasing utilization of older deceased donors in the last decades. Considering that definition of factors that influence deceased donor kidney transplant outcomes is important for allocation policies, as well as for individualization of post-transplant care, the purpose of this study was determine the risks for death censored graft survival and for patient survival conferred by older age of the donor in the context of the age of the recipient and of risk factors for graft and/or patient survival. The investigation was conducted in a single-center cohort of 5,359 consecutive first kidney transplants with adult deceased donors performed on non-prioritized adult recipients from January 1, 2002, to December 31, 2017. Death censored graft survival and patient survival were lower in older donors, whereas graft survival was higher and patient survival was lower in old recipients. The analyses of combinations of donor and recipient ages showed that death censored graft survival was lower in younger recipients in transplants from 18 to 59-year old donors, with standard or extended criteria, but no difference in graft survival was observed between younger and older recipients when the donor was ≥ 60-year old. Patient survival was higher in younger recipients in transplants with younger or older donors. Two to six HLA-A,B,DR mismatches, when compared to 0-1 MM, conferred risk for death-censored graft survival only in transplants from younger donors to younger recipients. Pre-transplant diabetes conferred risk for patient survival only in 50–59-year old recipients, irrespectively, of the age of the donor. Time on dialysis ≥ 10 years was a risk factor for patient survival in transplants with all donor-recipient age combinations, except in recipients with ≥ 60 years that received a kidney from an 18–49-year old donor. In conclusion, the results obtained in this study underline the importance of analyzing the impact of the age of the donor taking into consideration different scenarios.

Age and liver transplantation

The average age of liver transplant donors and recipients has increased over the years. Independent of the cause of liver disease, older candidates have more comorbidities, higher waitlist mortality and higher post-transplant mortality than younger patients. However, transplant benefit may be similar in older and younger recipients, provided older recipients are carefully selected. The cohort of elderly patients transplanted decades ago is also increasingly raising issues concerning long-term exposure to immunosuppression and aging of the transplanted liver. Excellent results can be achieved with elderly donors and there is virtually no upper age limit for donors after brain death liver transplantation. The issue is how to optimise selection, procurement and matching to ensure good results with elderly donors. The impact of old donor age is more pronounced in younger recipients and patients with a high model for end-stage liver disease score. Age matching between the donor and the recipient should be incorporated into allocation policies with a multistep approach. However, age matching may vary depending on the objectives of different allocation policies. In addition, age matching must be revisited in the era of direct-acting antivirals. More restrictive limits have been adopted in donation after circulatory death. Perfusion machines which are currently under investigation may help expand these limits. In living donor liver transplantation, donor age limit is essentially guided by morbidity related to procurement. In this review we summarise changing trends in recipient and donor age. We discuss the implications of older age donors and recipients. We also consider different options for age matching in liver transplantation that could improve outcomes.

Nonimmunologic Donor-Recipient Pairing, HLA Matching, and Graft Loss in Deceased Donor Kidney Transplantation

Background

In kidney transplantation, nonimmunologic donor-recipient (D-R) pairing is generally not given the same consideration as immunologic matching. The aim of this study was to determine how nonimmunologic D-R pairing relates to independent donor and recipient factors, and to immunologic HLA match for predicting graft loss.

Methods

Seven D-R pairings (race, sex, age, weight, height, cytomegalovirus serostatus, and HLA match) were assessed for their association with the composite outcome of death or kidney graft loss using a Cox regression-based forward stepwise selection model. The best model for predicting graft loss (including nonimmunologic D-R pairings, independent D-R factors, and/or HLA match status) was determined using the Akaike Information Criterion.

Results

Twenty three thousand two hundred sixty two (29.9%) people in the derivation data set and 9892 (29.7%) in the validation data set developed the composite outcome of death or graft loss. A model that included both independent and D-R pairing variables best predicted graft loss. The c-indices for the derivation and validation models were 0.626 and 0.629, respectively. Size mismatch (MM) between donor and recipient (>30 kg [D < R} and >15 cm [D < R]) was associated with poor patient and graft survival even with 0 HLA MM, and conversely, an optimal D-R size pairing mitigated the risk of graft loss seen with 6 HLA MM.

Conclusions

D-R pairing is valuable in predicting patient and graft outcomes after kidney transplant. D-R size matching could offset the benefit and harm seen with 0 and 6 HLA MM, respectively. This is a novel finding.

The effects of donor age on organ transplants: A review and implications for aging research

Despite the considerable amount of data available on the effect of donor age upon the outcomes of organ transplantation, these still represent an underutilized resource in aging research. In this review, we have compiled relevant studies that analyze the effect of donor age in graft and patient survival following liver, kidney, pancreas, heart, lung and cornea transplantation, with the aim of deriving insights into possible differential aging rates between the different organs. Overall, older donor age is associated with worse outcomes for all the organs studied. Nonetheless, the donor age from which the negative effects upon graft or patient survival starts to be significant varies between organs. In kidney transplantation, this age is within the third decade of life while the data for heart transplantation suggest a significant effect starting from donors over age 40. This threshold was less defined in liver transplantation where it ranges between 30 and 50 years. The results for the pancreas are also suggestive of a detrimental effect starting at a donor age of around 40, although these are mainly derived from simultaneous pancreas-kidney transplantation data. In lung transplantation, a clear effect was only seen for donors over 65, with negative effects of donor age upon transplantation outcomes likely beginning after age 50. Corneal transplants appear to be less affected by donor age as the majority of studies were unable to find any effect of donor age during the first few years posttransplantation. Overall, patterns of the effect of donor age in patient and graft survival were observed for several organ types and placed in the context of knowledge on aging.

•

Data on the effects of donor age upon the outcomes of organ transplantation are an underutilized resource in biogerontology

•

We compiled data on the effect of donor age following liver, kidney, pancreas, heart, lung and cornea transplantation

•

Older donor age is associated with worse outcomes for all the organs studied

•

The donor age from which the negative effects upon survival starts to be significant varies between organs

Personalized immunosuppression in elderly renal transplant recipients

The number of elderly people has increased considerably over the last decades, due to a rising life expectancy and ageing populations. As a result, an increased number of elderly with end-stage-renal-disease are diagnosed, for which the preferred treatment is renal transplantation. Over the past years the awareness of the elderly as a specific patient population has grown, which increases the importance of research in this group. Elderly patients often receive kidneys from elderly donors while younger donor kidneys are preferentially reserved for younger recipients. Although the rate of acute rejection after transplantation is lower in the elderly, these rejections may lead to graft loss more frequently, as kidneys from elderly donors have marginal reserve capacity. To prevent acute rejection, immunosuppressive therapy is needed. On the other hand, elderly patients have a higher risk to die from infectious complications, and thus less immunosuppression would be preferable. Immunosuppressive treatment in the elderly is complicated further by changes in the pharmacokinetics and pharmacodynamics, with increasing age. Adjustments in standard immunosuppressive regimes are therefore suggested for this population. An unmet need in transplantation medicine is a tool to guide a personalized approach to immunosuppression. Recently several promising biomarkers that identify injury to the graft at an early stage or predict acute rejection have been identified. Unfortunately, none of these biomarkers were tested specifically in the elderly. We believe there is an urgent need to perform clinical trials investigating novel immunosuppressive regimens in conjunction with biomarker studies in this specific population.

Kidney transplant outcomes from older deceased donors: a paired kidney analysis by the European Renal Association-European Dialysis and Transplant Association Registry

As the median age of deceased kidney donors rises, updated knowledge of transplant outcomes from older deceased donors in differing donor-recipient age groups is required. Using ERA-EDTA Registry data we determined survival outcomes of kidney allografts donated from the same older deceased donor (55-70 years), and transplanted into one recipient younger and one recipient of similar age to the donor. The recipient pairs were divided into two groups: group 1; younger (median age: 52 years) and older (60 years) and group 2; younger (41 years) and older (60 years). A total of 1410 adults were transplanted during 2000-2007. Compared to the older recipients, the mean number of functioning graft years at 10 years was 6 months longer in the group 1 and group 2 younger recipients (P < 0.001). Ten-year graft survival was 54% and 40% for the group 1 younger and older recipients, and 60% and 49% for the group 2 younger and older recipients. Paired Cox regression analyses showed a lower risk of graft failure (group 1 younger; adjusted relative risk [RRa]:0.57, 95% CI:0.41-0.79, and group 2 younger; RRa:0.63, 95% CI:0.47-0.85) in younger recipients. Outcomes from older deceased donor allografts transplanted into differing donor-recipient age groups are better than previously reported. These allografts remain a valuable transplant resource, particularly for similar-aged recipients.

[Focusing on kidney transplantation in the elderly]

Due to the increase in life expectancy and the ageing of end-stage renal disease patients, the number of patients older than 65 years receiving a kidney transplant has been continuously growing over the last fifteen years. The benefits of renal transplantation compared to dialysis in terms of survival and quality of life have been shown in selected recipients over 65, or 70 years. However, the age remains the main limiting factor for the access to the waiting list, and the reluctance of the clinicians can be explained by the multiple comorbidities of these candidates, their limited life expectancy or the shortage of grafts. The challenge is to select the candidates who can benefit from renal transplantation, thanks to rigorous cardiovascular and neoplastic evaluation before enrolment and by taking into account the specific characteristics of elderly patients. The living donor appears to be the ideal option for elderly recipients, the alternative being the extended criteria donor, allowing waiting times to be limited. The choice of immunosuppressive therapy is also crucial in these patients at high risk of infectious and cardiovascular complications in whom the occurrence of acute rejection can have severe consequences. There are currently no specific recommendations for immunosuppression in elderly recipients, and we would need large-scale randomized studies to improve the prognosis of renal transplantation in this population.

Strategies for an Expanded Use of Kidneys From Elderly Donors

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

Current Status of Kidney Transplant Outcomes: Dying to Survive

Kidney transplantation is associated with improved survival compared with maintenance dialysis. In the United States, post-transplant outcomes have steadily improved over the last several decades, with current 1-year allograft and patient survival rates well over 90%. Although short-term outcomes are similar to those in the international community, long-term outcomes appear to be inferior to those reported by other countries. Differences in recipient case mix, allocation polices, and health care coverage contribute to the long-term outcome disparity. This review presents the current status of kidney transplant outcomes in the United States and compares them with the most recent outcomes from Australia and New Zealand, Europe, and Canada. In addition, early trends after implementation of the new kidney allocation system in the United States and its potential impact on post-transplant outcomes are discussed.

Kidney Graft Survival in Italy and Factors Influencing it

Purpose

National registry data are often a suitable basis for examination of transplant outcomes. Using data supplied by the Italian National Transplant Registry, established in 1995, we performed the first nationwide analysis of this kind.

Methods

A retrospective analysis of 4893 recipients of cadaveric kidneys transplanted in all Italian centers from 1995 through 2000 was done to study 5-year graft survival. The association between some donor and recipient variables and outcomes in renal transplantation was analyzed. Graft survival was 93% at 3 months, 89% at 1 year, 82% at 3 years, and 80% at 5 years after transplantation.

Results

A significant association between graft survival and donor age (old vs young, relative risk [RR] = 1.62, 95% CI 1.27–2.06) and recipient age (old vs young, RR = 1.25, 95% CI 1.02–1.53). Graft survival was also associated with cold ischemia time (24–36 hours, RR=1.39, 95% CI 1.05–1.85 and >36 hours, RR=1.94, 95% CI 1.32–2.86 vs 0–24 hours) and donor/recipient sex mismatch (female/male vs male/male, RR=1.50, 95% CI 1.17–1.93).

Conclusion

The quality of kidney transplantation in Italy is satisfactory and is comparable to that in other developed countries. Furthermore, our experience confirms that both donor and recipient factors are major determinants of renal allograft function.

Living Donor Transplantation: Long-Term Evolution Related to Age Matching

The lack of donors is favoring living kidney donor (LKD) transplantation worldwide, quite often beyond the classic age-matching rules. We analysed renal function (RF) at 1 and 5 years in all donor and recipients as well as death-censored graft and patient survival. LKD recipients were divided into 4 subgroups: young recipients-young donors (YR-YD; N = 355), elderly recipients-young donors (ER-YD; N = 13), young recipients-elderly donors (YR-ED; N = 67), and elderly recipients-elderly donors (ER-ED; N = 38). "Elderly" was defined as ≥60 years. RF was better in those who received a young allograft (YR-YD/ER-YD) at any time (P < .001). There was a trend toward higher proteinuria among the recipients of an old allograft (YR-ED/ER-ED) at any time (P = not significant [NS]). However, our population showed low levels of proteinuria and this was not a risk factor for graft failure. Logistic regression model showed that creatinine level at 1 year is a good predictor of graft losses. Graft survival was worse in the allografts from elderly donors (P < .001). Analysing the young recipients, renal survival was inferior in those who received an old kidney (YR-ED; P < .00005) as well as mortality rates at 14 years (P = .03). The RF of young (N = 295) and elderly donors (N = 98) was optimal with no progression to ESRD or deaths registered during follow-up. In conclusion, young recipients of elderly kidneys pay the price of a worse RF, allograft prognosis, and patient prognosis. The pair YR-ED is a doable option, but we recommend age matching when it is possible.

What immunosuppression should be used for old-to-old recipients?

Elderly patients receiving a kidney from old donors (old-to-old) are a growing population of transplant recipients. This population cumulates risks of complications due to the co-morbidities and the immunodeficiency state and the frailty of the recipients together with the kidney senescence of the donors. In this context, the choice of immunosuppression is complicated and must take into account some contradictory principles explaining why no consensus exists today.

Transplanting the elderly: Balancing aging with histocompatibility

Across the world, the proportions of senior citizens (i.e. those ≥65years) increase rapidly and are predicted to constitute over 25% of the general population by 2050. In 2012 already 48% of the population with end stage renal disease (ESRD) was aged 65years or older. Transplantation is considered the preferred treatment option for ESRD offering survival advantage over long-term dialysis in the majority of patients. Indeed, acceptable outcomes have been documented for selected patients over the age of 70years or even cases over 80years. The reality of organ scarcity and prolonged waiting times for a deceased donor kidney transplantation, however, indicate that at best 50% of the selected elderly may have realistic expectations to receive a timely transplant offer. By choice or medical selection, access to transplantation also decreases with increasing age. In order to expedite the chance for elderly to receive a kidney transplant dedicated allocation systems have been developed. These allocation systems, like the Eurotransplant Senior Program (ESP), support preferential local allocation of kidneys from older donors to older patients in order to match recipient and graft life while disregarding histocompatibility for HLA antigens. The consequence has been more acute rejection episodes and an increase in immunosuppressive load. In the elderly, the most common cause of graft loss is death with functioning graft and death from infectious diseases is one of the dominant causes. The Eurotransplant Senior DR-compatible Program (ESDP) was designed to further improve the perspective of successful transplantation in the elderly in terms of life and quality of life by re-introducing matching criteria for HLA-DR in the old-for-old algorithm.

Age matching improves graft survival after living donor kidney transplantation

BACKGROUND

Donor and recipient age in kidney transplantation are known to affect graft and patient survival. To address the question of whether the age difference between donor and recipient impacts on graft survival and death-censored graft survival after transplantation, we examined the impact of age matching (less than 10-year age difference) on the survivals after living donor kidney transplantation.

METHODS

Two hundred one cases of the primary living donor kidney transplantation were performed and were divided into two groups, age-matched (n = 123) versus age-discrepant (n = 78). Variables included in this study were age, gender, body weight, height, kidney disease, type and duration of dialysis before transplantation, degree of human leukocyte antigen mismatch, ischemic time, graft weight, episode of rejection, type of immunosuppression, recipient serum creatinine after transplantation, and causes of patient death and graft loss.

RESULTS

We observed the disparities of graft survival (P = .008) and death-censored graft survival (P = .003) between the groups. One-, 3-, and 5-year death-censored graft survival was 100%, 100%, and 97% in the age-matched group, respectively; and 97%, 90%, and 88% in the age-discrepant group, respectively. By Cox regression multivariate analysis, the variable of age-matching was an independent predictor for both graft survival (ß = 1.325, P = .017) and death-censored graft survival (ß = 2.217, P = .021).

CONCLUSION

During living donor and recipient matching, age difference between donor and recipient should be minimized.

A single-center cohort study to define the role of pretransplant biopsy score in the long-term outcome of kidney transplantation

BACKGROUND

The role of pretransplant biopsy in defining the quality of kidney grafts is still debated. The aim of this study was to investigate the influence of pretransplant biopsy score on long-term graft outcome.

METHODS

In a retrospective cohort study, we analyzed 372 recipients of single kidney transplantation (SKT) from deceased donors between 1997 and 2007, with an available pretransplant biopsy. We evaluated 5- and 10-year graft survival, incidence of delayed graft function, and estimated glomerular filtration rate at 1 and 5 years.

RESULTS

Graft survival at 5 and 10 years was significantly better for recipients with a score of 0 compared to transplants with a score of 1 to 5, whereas we did not observe any significant difference among transplants with a score of 1 through 4. Survival of kidneys with a score of 5 was significantly worse compared to grafts with a score of 1 to 4. In a multivariate Cox model, only pretransplant histological score was significantly associated with graft survival. Transplants with a score of 0 and 5 had the best and the worst graft function, respectively, both at 1 and 5 years, whereas we did not observe any difference among patients with a score of 1 through 4. In a multivariate logistic regression, pretransplant histological score was independently associated with the prevalence of an estimated glomerular filtration rate less than 30 mL/min at 5 years. Finally, delayed graft function rate was significantly higher in recipients with a score of 5 compared to patients with a score of 1 to 4 and score of 0.

CONCLUSIONS

Our data suggest that 1) pretransplant histological score may predict long-term graft outcome and 2) allocation of kidneys with a score of 4 to SKT provides an acceptable long-term graft function and survival.

Strategies to increase the donor pool and access to kidney transplantation: an international perspective

In this position article, DESCARTES (Developing Education Science and Care for Renal Transplantation in European States) board members describe the current strategies aimed at expanding living and deceased donor kidney pools. The article focuses on the recent progress in desensitization and kidney paired exchange programmes and on the expanded criteria for the use of donor kidneys and organs from donors after circulatory death. It also highlights differences in policies and practices across different regions with special regard to European Union countries. Living donor kidney paired exchange, the deceased donor Acceptable Mismatch Programme and kidneys from donors after circulatory death are probably the most promising innovations for expanding kidney transplantation in Europe over the coming decade. To maximize success, an effort is needed to standardize transplant strategies, policies and legislation across European countries.

Kidney transplantation outcomes from expanded criteria donors, standard criteria donors or living donors older than 60 years

OBJECTIVES

To evaluate outcomes in kidney allograft recipients from donors with expanded criteria (ECD) versus standard criteria (SCD) or living donors (LD) >60 years.

METHODS

We studied all patients who received a kidney between 2005 and 2011, focusing in recipients of kidneys from deceased ECD, SCD and LD >60 years. ECD was any deceased donor >60 years or >50 years with two of the following: hypertension (HTN), stroke as the cause of death, or serum creatinine >1.5 mg/dL. We recorded characteristics of the transplant procedure, patient, graft survival and renal function 1 year after transplantation and at the end of follow-up.

RESULTS

Six-hundred and five patients were transplanted between 2005 and 2011 in our department. There were 142 (25.1%) transplantations from ECD, 192 (33.98%) from SCD and 96 (16.99%) from LDs older than 60 years. In a mean follow-up time of 36.4 months, graft survival rates were similar for all groups. Calculated GFR was found statistically different between the ECD and SCD groups, but still satisfactory at first year, and at end of follow-up time. Comparison of the patients, who received transplants from ECD, even older than 70 years, and those from LD >60 years revealed equivalent renal function in short and long term.

CONCLUSIONS

Utilization of marginal kidneys effectively doubled our deceased transplant volume in the period 2005-2011. Patients' and graft survival were shown similar at the end of follow-up for all groups. Renal outcomes were shown equivalent between the ECD and LD >60 years groups, and although significantly lower between the ECD and the SCD group, were still very satisfactory.

Outcomes and survival analysis of old-to-old simultaneous pancreas and kidney transplantation

Outcomes of old-donor simultaneous pancreas-kidney transplantation (SPKT) have not been thoroughly studied. Scientific Registry of Transplant Recipients data reported for SPKT candidates receiving dialysis wait-listed between 1993 and 2008 (n = 7937) were analyzed for outcomes among those who remained listed (n = 3301) and of SPKT recipients (n = 4636) using multivariable time-dependent regression models. Recipients were stratified by donor/recipient age (cutoff 40 years) into: young-to-young (n = 2099), young-to-old (n = 1873), old-to-young (n = 293), and old-to-old (n = 371). The overall mortality was 12%, 14%, 20%, and 24%, respectively, for those transplanted, and 50% for those remaining on the waiting list. On multivariable analysis, old-donor SPKT was associated with significantly higher overall risks of patient death, death-censored pancreas, and kidney graft failure in both young (73%, 53%, and 63% increased risk, respectively) and old (91%, 124%, and 85% increased risk, respectively) recipients. The adjusted relative mortality risk was similar for recipients of old-donor SPKT compared with wait-listed patients including those who subsequently received young-donor transplants (aHR 0.95; 95% CI 0.78, 1.12) except for candidates in OPOs with waiting times ≥604 days (aHR 0.65, 95% CI 0.45-0.94). Old-donor SPKT results in significantly worse graft survival and patient mortality without any waiting-time benefit as compared to young-donor SPKT, except for candidates with expected long waiting times.

Effects of Aging on Kidney Graft Function, Oxidative Stress and Gene Expression after Kidney Transplantation

Conflicting results have been reported regarding the effects of donor age, recipient age and donor-recipient age difference on short- and long-term outcomes after kidney transplantation. The aim of this study was to evaluate the effects of recipient age on graft function, oxidative stress, and gene expression after renal transplantation. Fifty male Fischer 344 rats [25 young (Y, 4 months), 25 senior (S, 16 months)] were randomized to 6 groups: 2 sham groups (Y and S, n = 5 in each group) and 4 renal transplant groups[young-to-young (Y-Y), young-to-senior (Y-S), senior-to-young (S-Y), senior-to-senior (S-S), (n = 10 in each group)]. The left kidneys were transplanted from donor to recipient. After 12 weeks, systematic blood pressure, graft weight, graft function, histology and oxidative stress were measured. Microarray analysis and quantitative real-time PCR confirmation were performed to study gene expression in the grafts. There were no differences in renal graft function between young and senior kidney cross-transplantation. Transplanted kidneys showed no significant differences in glomerulosclerosis index compared to non-transplanted kidneys but had significantly different tubulointerstitium scores compared to age-matched controls. Senior rats had lower SOD activity and higher MDA content than young rats. SOD activity was significantly lower and MDA content significantly higher in the Y-S group than in the Y-Y group. There were 548 transcript differences between senior and young kidneys with 36 upregulated and 512 downregulated transcripts. There were 492 transcript differences between Y-S and Y-Y groups with 127 upregulated and 365 downregulated transcripts. There were 1244 transcript differences between the S-Y and S-S groups with 680 upregulated and 574 downregulated transcripts. Oxidative stress and gene expression profile was significantly different in the Y-S compared to the S-Y group. The identified differences were mainly in the MAPK and insulin signal pathways, making these potential targets for therapeutic intervention.

Immunosenescence and organ transplantation

Increasing numbers of elderly transplant recipients and a growing demand for organs from older donors impose pressing challenges on transplantation medicine. Continuous and complex modifications of the immune system in parallel to aging have a major impact on transplant outcome and organ quality. Both, altered alloimmune responses and increased immunogenicity of organs present risk factors for inferior patient and graft survival. Moreover, a growing body of knowledge on age-dependent modifications of allorecognition and alloimmune responses may require age-adapted immunosuppression and organ allocation. Here, we summarize relevant aspects of immunosenescence and their possible clinical impact on organ transplantation.

Long-term results of biopsy-guided selection and allocation of kidneys from older donors in older recipients

In our old-for-old program, we discard or allocate older extended criteria donor kidneys to single (SKT) or dual kidney transplantation (DKT) depending on histological Remuzzi's score in recipients older than 60 years. Here, we analyze the long-term results of this program and try to identify independent predictors of patient and graft survival. Between December 1996 and January 2008, we performed 115 SKT and 88 DKT. Discard rate was 15%. Acute rejection incidence was higher in SKT than in DKT (22.6% vs. 11.4%, p = 0.04). Renal function was better in DKT than in SKT up to 5 years after transplantation. Surgical complications were frequent in DKT. Ten-year cumulative graft survival was significantly lower in the SKT group (31% vs. 53%, p = 0.03). In SKT, histological score 4 provided similar graft survival than 3 or less, whereas in DKT score 4, 5 or 6 displayed similar outcome. Finally, independent predictors of graft survival were history of major adverse cardiac event and 1-year serum creatinine, rather than SKT or DKT. In conclusion, this biopsy-guided old-for-old strategy resulted in acceptable long-term graft survival. Our results suggest that DKT should be considered for scores of 5 or 6 only.

Kidney donation after cardiac death

There is continuing disparity between demand for and supply of kidneys for transplantation. This review describes the current state of kidney donation after cardiac death (DCD) and provides recommendations for a way forward. The conversion rate for potential DCD donors varies from 40%-80%. Compared to controlled DCD, uncontrolled DCD is more labour intensive, has a lower conversion rate and a higher discard rate. The super-rapid laparotomy technique involving direct aortic cannulation is preferred over in situ perfusion in controlled DCD donation and is associated with lower kidney discard rates, shorter warm ischaemia times and higher graft survival rates. DCD kidneys showed a 5.73-fold increase in the incidence of delayed graft function (DGF) and a higher primary non function rate compared to donation after brain death kidneys, but the long term graft function is equivalent between the two. The cold ischaemia time is a controllable factor that significantly influences the outcome of allografts, for example, limiting it to < 12 h markedly reduces DGF. DCD kidneys from donors < 50 function like standard criteria kidneys and should be viewed as such. As the majority of DCD kidneys are from controlled donation, incorporation of uncontrolled donation will expand the donor pool. Efforts to maximise the supply of kidneys from DCD include: implementing organ recovery from emergency department setting; improving family consent rate; utilising technological developments to optimise organs either prior to recovery from donors or during storage; improving organ allocation to ensure best utility; and improving viability testing to reduce primary non function.

Lack of impact of donor age on patient survival for renal transplant recipients ≥60years

There has been an increase in the number of older patients on the transplant waiting list and acceptance of older donor kidneys. Although kidneys from older donors have been associated with poorer graft outcomes, whether there is a differential impact of donor age on outcomes in older recipients remains unclear. The aim of this study was to evaluate the effect of donor age on graft and patient survival in renal transplant (RT) recipients ≥60years. Using the Australia and New Zealand Dialysis and Transplant Registry, outcomes of 1,037 RT recipients ≥60years between 1995 and 2009 were analyzed. Donor age groups were categorized into 0-20, >20-40, >40-60, and >60years. Compared with recipients receiving donor kidneys >60years, those receiving donor kidneys >20-40years had lower risk of acute rejection (odds ratio 0.46, 95% CI 0.27, 0.79; P<0.01) and death-censored graft failure (HR 0.37, 95% CI 0.19, 0.72; P<0.01). There was no association between donor age groups and death. With a corresponding growth in the availability of older donor kidneys and the observed lack of association between donor age and patient survival in RT recipients ≥60years, preferential allocation of older donor kidneys to RT recipients ≥60years may not disadvantage the life expectancy of these patients.

A review of utility-based allocation strategies to maximize graft years of deceased donor kidneys

With the continuing shortage of deceased donor kidneys coupled with a growing number of older potential recipients, there has been a greater acceptance of using older donor kidneys, including increased utility of expanded criteria donor (ECD) kidneys. In this review, we will look at the impact of using ECD kidneys on graft and patient survival, and to identify modifiable factors that may improve transplant outcomes in recipients receiving ECD kidneys. In addition, we will discuss whether the implementation of utility-based allocation strategies to maximize graft outcomes is an appropriate way forward to provide a better balance between utility and equity in the distribution of deceased donor kidneys.

Impact of age matching of donors to recipients on renal transplant outcomes following donation after cardiac death

Organ donation after cardiac death (DCD) provides a valuable supply of grafts for renal transplantation. Age matching of donors to recipients is often used. We sought to determine the impact of age matching on the outcomes among our cohort of DCD renal transplant recipients. Using our institutional database, we gathered information on all DCD renal transplants performed between April 2002 and December 2009. We divided the cohort into two groups based upon the donor:recipient age ratio: age-matched (between 25th and 75th percentiles, n = 99) and non-age-matched (<25th percentile and >75th centile, n = 100). We failed to demonstrate any significant difference between the two groups in terms of early complications or long-term outcome or function. Age matching did not appear to affect graft outcomes, particularly for young donors, but may have a role in older donors.

Donor-recipient age matching improves years of graft function in deceased-donor kidney transplantation

BACKGROUND

Donor and recipient age in kidney transplantation are known to affect graft and patient survival. In deceased-donor (DD) transplantation, donor and recipient age matching are being increasingly accepted as part of the kidney allocation programme. The aims of this study are to evaluate the effect of donor and recipient age on transplant outcomes and to determine the effect of changing existing allocation criteria to allocation based on age matching of donors and recipients on total graft years of function.

METHODS

Using the Australia and New Zealand Dialysis and Transplant Registry, all DD kidney transplant recipients in Australia and New Zealand between 1991 and 2006 were analysed (n = 4616). Outcomes analysed were overall graft failure, death with functioning graft and serum creatinine. We calculated the mean time to graft loss ('years of graft function') for donor and recipient age cut-offs as 60 and 55 years, respectively, over up to 16 years follow-up. We then examined the gain in graft years if all older kidneys were allocated to older recipients.

RESULTS

Older donors were associated with higher risk of overall graft failure [adjusted hazard ratio (HR) = 1.79, 95% confidence interval (95% CI) = 1.45, 2.21 and HR = 1.29, 95% CI = 1.09, 1.53, respectively] at 1-8 years post-transplant and higher serum creatinine at 1 and 5 years post-transplant (mean differences 32.74 micromol/L, 95% CI 27.60, 37.89 and 38.17 micromol/L, 95% CI 27.58, 48.77, respectively). Overall, young and old recipients with young donor kidneys have an additional two to three mean graft years compared to those receiving older donor kidneys.

CONCLUSION

Donor and recipient age matching is an effective method of organ allocation to improve total graft years.