The combination of donor and recipient age is critical in determining host immunoresponsiveness and renal transplant outcome. Ann Surg. 2010;252:662-674. [PMID: 20881773 DOI: 10.1097/sla.0b013e3181f65c7d]

The combined risk of donor quality and recipient age: higher-quality kidneys may not always improve patient and graft survival

BACKGROUND

The Kidney Donor Profile Index (KDPI) is a more precise donor organ quality metric replacing age-based characterization of donor risk. Little prior attention has been paid on the outcomes of lower-quality kidneys transplanted into elderly recipients. Although we have previously shown that immunological risks associated with older organs are attenuated by advanced recipient age, it remains unknown whether risks associated with lower-quality KDPI organs are similarly reduced in older recipients.

METHODS

Donor organ quality as measured by the KDPI was divided into quintiles (very high, high, medium, low, and very low quality), and Cox proportional hazards was used to assess graft and recipient survival in first-time adult deceased donor transplant recipients by recipient age.

RESULTS

In uncensored graft survival analysis, recipients older than 69 years had demonstrated comparable outcomes if they received low-quality kidneys compared to medium-quality kidneys. Death-censored analysis demonstrated no increased relative risk when low-quality kidneys were transplanted into recipients aged 70 to 79 years (hazard ratio [HR], 1.11; P=0.19) or older than 79 years (HR, 1.08; P=0.59). In overall survival analysis, elderly recipients gained no relative benefit from medium-quality kidneys over low-quality kidneys (70-79 years: HR, 1.03, P=0.51; >79 years: HR, 1.08; P=0.32).

CONCLUSION

Our analysis demonstrates that transplanting medium-quality kidneys into elderly recipients does not provide significant advantage over low-quality kidneys.

Efficacy of everolimus with reduced-exposure cyclosporine in de novo kidney transplant patients at increased risk for efficacy events: analysis of a randomized trial

The efficacy of de novo everolimus with reduced-exposure calcineurin inhibitor (CNI) was examined in kidney transplant subpopulations from the A2309 study that were identified to be at increased risk for efficacy events. A2309 was a 24-month, multicenter, open-label trial in which 833 de novo kidney transplant recipients were randomized to everolimus targeting 3-8 or 6-12 ng/ml with reduced-exposure cyclosporine (CsA), or mycophenolic acid (MPA) with standard-exposure CsA, all with basiliximab induction. The composite efficacy endpoint was treated biopsy-proven acute rejection (BPAR), graft loss, death, or loss to follow-up. Cox proportional hazard modeling showed male gender, younger recipient age, black race, delayed graft function, human leukocyte antigen (HLA) mismatch ≥3 and increasing donor age to be significantly predictive for the composite efficacy endpoint at months 12 or 24 post-transplant. CsA exposure was 53-75 % lower, and 46-75 % lower, in patients receiving everolimus 3-8 ng/ml or receiving everolimus 6-12 ng/ml, respectively, versus MPA-treated patients. The incidence of the composite endpoint was similar in all three treatment groups within each subpopulation analyzed. The incidence of treated BPAR was similar with everolimus 3-8 ng/ml or MPA in all subpopulations, but less frequent with everolimus 6-12 ng/ml versus MPA in patients with HLA mismatch ≥3 (p = 0.049). This post hoc analysis of a large, randomized trial suggests that a de novo regimen of everolimus with reduced-exposure CsA maintains immunosuppressive efficacy even in kidney transplant patients at increased risk for efficacy events despite substantial reductions in CsA exposure.

Telomere length of recipients and living kidney donors and chronic graft dysfunction in kidney transplants

BACKGROUND

A biological marker that would allow clinicians to determine the length of time an allograft will remain functional after transplantation would greatly aid the ability to stratify donors by risk and to use biologically "young" allografts in young recipients, maximizing the use of this rare resource. Telomere length (TL) has been proposed to be such a marker to determine the biological age of a tissue.

METHODS

We genotyped DNA from 1805 recipients and 1038 living kidney donors for TL to determine the association of TL with acute rejection (AR), chronic graft dysfunction (CGD), and graft failure of kidney allografts. DNA was isolated from peripheral blood white blood cells and TL was measured in DNA using the multiplexed monochrome quantitative polymerase chain reaction assay.

RESULTS

As has been previously shown, we found a significant association between log-transformed TL and donor age (P=3.8×10) and recipient age (P=5.6×10). Univariate and multivariate analysis did not show any significant associations between log-transformed TL in donor or recipient DNA with AR, CGD, or graft failure, although we did observe an association between donor chronological age and CGD (P=0.018).

CONCLUSION

Although older allografts have been shown to be at greater risk for AR and CGD, this does not appear to be associated with shorter TL. Different markers will need to be identified to determine how biological age impacts transplant outcome, such as age-related fibrosis or tubular atrophy and tubular loss.

Prospective multicenter clinical trial of immunosuppressive drug withdrawal in stable adult liver transplant recipients

Lifelong immunosuppression increases morbidity and mortality in liver transplantation. Discontinuation of immunosuppressive drugs could lessen this burden, but the safety, applicability, and clinical outcomes of this strategy need to be carefully defined. We enrolled 102 stable liver recipients at least 3 years after transplantation in a single-arm multicenter immunosuppression withdrawal trial. Drugs were gradually discontinued over a 6 to 9-month period. The primary endpoint was the development of operational tolerance, defined as successful immunosuppressive drug cessation maintained for at least 12 months with stable graft function and no histopathologic evidence of rejection. Out of the 98 recipients evaluated, 57 rejected and 41 successfully discontinued all immunosuppressive drugs. In nontolerant recipients rejection episodes were mild and resolved over 5.6 months (two nontolerant patients still exhibited mild gradually improving cholestasis at the end of follow-up). In tolerant recipients no progressive clinically significant histological damage was apparent in follow-up protocol biopsies performed up to 3 years following drug withdrawal. Tolerance was independently associated with time since transplantation (odds ratio [OR] 1.353; P = 0.0001), recipient age (OR 1.073; P = 0.009), and male gender (OR 4.657; P = 0.016). A predictive model incorporating the first two clinical variables identified subgroups of recipients with very high (79%), intermediate (30%-38%), and very low (0%) likelihood of successful withdrawal.

CONCLUSION

When conducted at late timepoints after transplantation, immunosuppression withdrawal is successful in a high proportion of carefully selected liver recipients. A combination of clinical parameters could be useful to predict the success of this strategy. Additional prospective studies are now needed to confirm these results and to validate clinically applicable diagnostic biomarkers.

Immunosenescence and immune response in organ transplantation

The immune system undergoes a complex and continuous remodeling with aging. Immunosenescence results into both quantitative and qualitative changes of specific cellular subpopulations that have major impact on allorecognition and alloresponse, and consequently on graft rejection and tolerance. Here, we are going to review the immunological changes associated with the aging process relevant for transplantation. Interventions to selectively target changes associated with the senescence process seem promising therapeutic strategies to improve transplantation outcome.

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.

Recipient-related predictors of kidney transplantation outcomes in the elderly

BACKGROUND

It is not clear whether in old people with end-stage renal disease kidney transplantation is superior to dialysis therapy.

METHODS

We compared mortality rates between kidney transplant recipients (KTRs) and the general population across different age categories. We also examined patient and allograft survival in 15 667 elderly KTRs (65-<90 yr old, 36% female) within three age subgroups (65-<70, 70-<75, and ≥75 yr).

RESULTS

The rise in the relative risk of death in older age groups was substantially less in KTRs than in the general population, that is, 1.8 and 2.0 vs. 21.4 and 76.6 in those aged 65-<75 and ≥75 yr, respectively, compared with 15- to <65-yr-old people (reference group). In 65- to <70-yr-old KTRs, obesity (BMI>30 kg/m(2) ) was associated with 19% higher risk of graft failure (HR: 1.19 [1.07-1.33], p = 0.002). Diabetes was a predictor of worse patient survival in all age groups but poorer allograft outcome in the youngest age group (65-<70 yr old) only. None of the examined risk factors affected allograft outcome in the oldest group (≥75 yr old) although there was a 49% lower trend of graft failure in very old Hispanic recipients (HR: 0.51 [0.26-1.01], p = 0.05).

CONCLUSIONS

Kidney transplantation may attenuate the age-associated increase in mortality, and its superior survival gain is most prominent in the oldest recipients (≥75 yr old). The potential protective effect of kidney transplantation on longevity in the elderly deserves further investigation.

Update on the long-term complications of renal transplantation

INTRODUCTION

Powerful immunosuppressive regimens have reduced rejection risk, leading to an expanding cohort of long-term kidney transplant recipients who are likely to encounter practitioners in other specialties.

SOURCES OF DATA

Key review papers and primary literature identified through searches of PubMed, Google Scholar and Medline.

AREAS OF AGREEMENT

Death from cardiovascular disease and malignancy remain the chief causes of transplant loss. Risk factors and phenotypes for these differ from the general population.

AREAS OF CONTROVERSY

Many guidelines for renal transplant recipients are based on extrapolation from studies on non-transplant cohorts and may not be appropriate. Emerging studies demonstrate that established interventions in the general population are less efficacious in transplant recipients.

GROWING POINTS

The influence of immunosuppression on the development of complications.

AREAS TIMELY FOR DEVELOPING RESEARCH

Markers to guide individualized optimal immunosuppression and predict the development of complications would allow for targeted early intervention.

Recipient age and time spent hospitalized in the year before and after kidney transplantation

BACKGROUND

Kidney transplantation (KT) is a life-prolonging therapy in certain older end-stage renal disease patients, but concerns regarding peritransplantation morbidity remain. We estimate the relative increase in time spent hospitalized in the year post-KT for older versus younger end-stage renal disease patients.

METHODS

This was a retrospective analysis of 27,247 Medicare-primary KT recipients from 2000 to 2005 using United States Renal Data System and Organ Procurement and Transplantation Network data. Time spent hospitalized was enumerated in the year pre-KT and post-KT from Medicare Part A claims. Excess inpatient days were the difference in an individual's post-KT and pre-KT hospital and skilled nursing facility days, standardized by time spent alive in the year post-KT.

RESULTS

The median excess inpatient days were similar by age group (9 in recipients 65 years or older vs. 7 in recipients younger than 65 years); however, the distribution was skewed, such that many more older adults had large increases in inpatient time (8.6% totaled >120 excess inpatient days vs. 4.2% in younger recipients). Among older recipients, risk factors for poor outcomes included recipient age, donor age, longer dialysis vintage, diabetic nephropathy, and congestive heart failure. Reasons for posttransplantation hospitalization were similar by age with the exception of rehabilitation, which was common only in the 65+ age group. Mean inpatient costs were equivalent pretransplantation by age but significantly higher posttransplantation among older KT recipients.

CONCLUSIONS

Posttransplantation morbidity may not be so different in most of the older individuals selected for KT; however, a minority fares much worse.

Impact of recipient age on whole organ pancreas transplantation

AIM

The goal of this study was to assess the impact of recipient age on post-transplant outcome.

METHODS

All pancreas transplants performed at Indiana University between 2003 and 2011 were reviewed. Demographic data were compared using standard chi-square and ANOVA testing. Standard Cox regression survival analysis was performed using a direct entry method for covariates.

RESULTS

Patients (n = 405) were divided by decade: <30 yr (n = 37), 30-39 (n = 109), 40-49 (n = 156), 50-59 (n = 85), and ≥ 60 yr of age (n = 18). Group demographics did not differ except for median ischemia time, which was between 7.0 and 8.5 h (p = 0.02). Early graft loss and one yr graft and patient survival were similar between the groups. Long-term patient survival demonstrated a trend toward decreased five-yr survival with increasing recipient age (p = NS). Graft survival at five yr by Cox regression was the lowest for the <30 yr group (74%), while all other groups were similar around 80% (p = NS).

CONCLUSION

No statistically significant differences in pancreas transplant outcomes were demonstrated when recipients were stratified by recipient age. These results suggest that older recipients can successfully undergo pancreas transplantation and expect five-yr outcomes similar to those seen in younger recipients.

Kidney transplantation and the ageing immune system

The world population is rapidly growing and ageing at a pace that is projected to continue for at least three decades. This shift towards an older populace has invariably increased the number of individuals with diseases related to ageing, such as chronic kidney disease. The increase in chronic kidney disease is associated with a growing number of elderly patients receiving kidney transplants. Understanding how the immune system changes with increasing age will help to define the risks of rejection and infection in the elderly population and will focus attention on the need for individualized immunosuppression for patients in this age group. This Review addresses what is currently known about ageing and the immune system, highlighting age-related changes that affect the outcome of transplantation in elderly individuals. The need for new strategies to improve outcomes in this growing population of elderly renal transplant recipients is also emphasized.

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.

Donor age-specific injury and immune responses

Utilization rates of organs from elderly donors have shown the highest proportional increase during the last decade. Clinical reports support the concept of transplanting older organs. However, the engraftment of such organs has been linked to accelerated immune responses based on ageing changes per se and a proinflammatory environment subsequent to compromised injury and repair mechanism. We analyzed the clinical consequences of transplanting older donor organs and present mechanistic aspects correlating age, injury repair and effects on host immunoresponsiveness.

Age is an important predictor of kidney transplantation outcome

BACKGROUND

Donor and recipient age may have an impact on the renal transplant outcome. Kidney transplantation from older donors may result in a worse outcome, and the survival benefit of kidney transplantation compared with dialysis may be reduced. The aim of this study was to evaluate the impact of donor and recipient age on kidney transplant outcome.

MATERIALS AND METHODS

Two hundred and twenty-three recipients of kidney transplants performed at our institution between 2002 and 2007 were analysed. The role of donor and recipient age matching on survival rate were investigated performing the Kaplan-Meier survival time analysis by decades, considering the donor's age of 60 and 70 years. The Cox proportional hazard uni- and multivariate regressions were also performed. Finally, Kaplan-Meier survival time analysis was performed to assess survival rates of patients transplanted stratified by donor age compared with wait-listed renal transplant candidates.

RESULTS

Elderly recipients had a significant lower graft and patient survival as well as a significantly higher risk of graft loss and patient death. Recipients younger and older than 65 years of age were at higher risk of graft loss if they received grafts from donors>65 years [hazard ratio (HR)=2.59, 95% confidence interval (CI): 1.12-6 and HR=5.65, 95% CI: 2.31-13.79, respectively]. Elderly recipients displayed a worse survival compared with transplant candidates on the waiting list.

CONCLUSIONS

Age is an important predictor of kidney transplantation outcome. Kidney transplantation does not offer a significant survival benefit in the intermediate term, compared to the waiting list, to elderly recipients transplanted with grafts from older donors. However, it cannot be excluded that it is still possible that there is a long-term benefit of transplantation over dialysis in this group of patients.

Consequences of transplant quality on chronic allograft nephropathy

Using kidneys from expanded-criteria donors to alleviate organ shortage has raised concern on reduced transplant outcomes. In this paper, we review how critical donor-related factors such as donor age, brain death, and consequences of ischemia-reperfusion injury (IRI) determine graft quality and impact chronic allograft nephropathy. We propose that combinatorial effects of organ-intrinsic features associated with increasing age and unspecific injuries related to brain death and IRI will impact innate and adaptive immune responses. Future research will need to explore avenues to optimize donor management, organ preservation, adapted immunosuppressive strategies, as well as modifications of the allocation of suboptimal allografts.