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† These authors contributed equally to this manuscript and share first authorship.
Alberto Artiles
Footnotes
† These authors contributed equally to this manuscript and share first authorship.
Affiliations
Urology Department, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Alcalá University, Madrid, Spain
† These authors contributed equally to this manuscript and share first authorship.
Ana Domínguez
Footnotes
† These authors contributed equally to this manuscript and share first authorship.
Affiliations
Urology Department, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Alcalá University, Madrid, Spain
Urology Department, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Alcalá University, Madrid, Spain
Aix-Marseille University, Marseille, FranceDepartment of Urology & Renal Transplantation, La Conception University Hospital, Assistance-Publique, Marseille, France
Unit of Urological Robotic Surgery and Renal Transplantation, Careggi Hospital, University of Florence, Florence, ItalyDepartment of Experimental and Clinical Medicine, University of Florence, Florence, Italy
Urology Department, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Alcalá University, Madrid, Spain
‡ These authors contributed equally to this manuscript and share senior authorship.
Affiliations
Urology Department, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Alcalá University, Madrid, Spain
† These authors contributed equally to this manuscript and share first authorship. ‡ These authors contributed equally to this manuscript and share senior authorship.
Owing to population ageing, a growing number of kidney transplants (KTs) in elderly population are being performed. KT is the best treatment for patients with end-stage renal disease (ESRD). However, in older patients, the decision between dialysis and KT can be difficult due to potential inferior outcomes. Few studies have been published addressing this issue, and literature outcomes are controversial.
Objective
To conduct a systematic review and meta-analysis to appraise the evidence about outcomes of KT in elderly patients (>70 yr).
Evidence acquisition
A systematic review and meta-analysis (PROSPERO registration: CRD42022337038) was performed. Search was conducted on PubMed and LILACS databases. Comparative and noncomparative studies addressing outcomes (overall survival [OS], graft survival [GS], complications, delayed graft function [DGF], primary nonfunction, graft loss, estimated glomerular filtrate rate, or acute rejection) of KT in people older than 70 yr were included.
Evidence synthesis
Of the 10 357 yielded articles, 19 met the inclusion criteria (18 observational studies, one prospective multicentre study, and no randomised controlled trials), enrolling a total of 293 501 KT patients. Comparative studies reporting enough quantitative data for target outcomes were combined. There were significant inferior 5-yr OS (relative risk [RR], 1.66; 95% confidence interval [CI], 1.18–2.35) and 5-yr GS in the elderly group (RR, 1.37; 95% CI, 1.14–1.65) to those in the <70-yr group. Short-term GS at 1 and 3 yr was similar between groups, and similar findings occurred with DGF, graft loss, and acute rejection rates. Few data about postoperative complications were reported.
Conclusions
Elderly recipients have worse OS at all time points and long-term GS compared with younger recipients (<70 yr). Postoperative complications were under-reported and could not be assessed. The DGF, acute rejection, death with functioning graft, and graft loss were not inferior in elderly recipients. Geriatric assessment in this setting might be useful for selecting better elderly candidates for KT.
Patient summary
Compared with younger population, kidney transplant in elderly patients has inferior patient and graft survival outcomes in the long term.
]. The percentage of elderly patients on the waiting list for KT is growing in the past decades, as the number of KTs in this population is also increasing; population over 70 yr accounted for 12% of all recipients in France [
]. This group of patients will become clinically more relevant in the near future, as the number of people aged 75–84 yr in the European Union (EU) is projected to increase by 60.5% from 2018 to 2050 [
]. In Europe, the average age of recipients has increased by 10 yr over the past two decades, while in the USA, the proportion of patients aged 65–74 yr included in the waiting list increased from 2% in the 1990s to >10% in 2012 [
The definition of elderly people remains controversial, with different cut-off points existing in medical literature. Old people are defined by the United Nations in the World Population Ageing 2013 Report [
] as those aged >60 yr and very old as those aged >85 yr, while the World Health Organization (WHO) states that older people in developed countries are those aged >65 yr.
Undoubtedly, ageing implies complex medical conditions such as multiple comorbidities, frailty, and cognitive impairment, which can pose real barriers to KT and threaten its outcomes and patient status. Additionally, older population usually have immunity disorders, and all these issues may expose elderly patients to a higher risk of complications such as infections and post-transplant malignancies [
]. There is considerable debate in transplant community about the potential benefit of KT in elderly patients. Some studies in literature have reported their outcomes in recipients aged >70 yr with variable outcomes. In contrast to liver transplantation field, in which systematic reviews (SRs) have been performed to assess outcomes in elderly patients [
], to date there is no SR addressing the outcomes of KT in this population.
The aim of this study was to perform an SR and meta-analysis to appraise all available evidence about outcomes of KT in elderly patients (>70 yr). This age limit was decided by the European Association of Urology Young Academic Urologists (EAU-YAU) Kidney Transplantation Working Group, as it represents, to our knowledge, the elderly age in developed countries’ literature. The primary objectives were to assess graft survival (GS)—noncensored for death, patient overall survival (OS), and complications (according to the Clavien-Dindo classification) of patients aged >70 yr receiving a KT and to compare these with those in younger population.
The secondary objectives were as follows: (1) delayed graft function (DGF), defined as the need for dialysis during 1st week after KT; (2) primary nonfunction (PNF), defined as a permanent loss of allograft function starting immediately after transplantation; (3) graft loss rate, defined as the return to dialysis, retransplantation, or death; (4) estimated glomerular filtrate rate (eGFR); and (5) acute graft rejection confirmed histologically.
2. Evidence acquisition
2.1 Data sources and searches
This SR has been conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. The protocol for the review was uploaded in the PROSPERO database (CRD42022337038). Databases searched were PubMed/Medline and LILACS. Full strategy search, PICOTS (Population, Intervention, Comparator, Outcome, Type of study, Timing, and Setting) table, and inclusion criteria are shown in the Supplementary material.
No language or year restrictions were applied, and the database was complemented by screening the reference list of the included studies.
2.2 Inclusion criteria and study eligibility
Studies eligible for inclusion were those reporting outcomes (at least one primary or secondary endpoint) of patients older than 70 yr who underwent KT (in single-arm studies) and those younger than 70 yr (in comparative ones). All study designs were eligible for inclusion, except reviews, editorials, letter to the editor, case reports, and studies published only as a conference abstract. Studies included were comparative studies and single-arm case series (incorporating a single intervention of KT in patients over 70 yr of age). All studies must have a minimum follow-up of 1 yr.
All identified abstracts were placed in a bibliography management software program (Mendeley) and sorted according to inclusion and exclusion folders by drag and drop. Titles and abstracts of all identified studies were reviewed independently by three authors (A.A., A.D., and J.D.S.), and discrepancies were resolved by a fourth reviewer (V.H.). The detailed inclusion criteria are summarised in the Supplementary material.
2.3 Data extraction
Data from eligible reports were extracted independently (A.A., A.D., and J.D.S.), and discrepancies were resolved by a fourth reviewer (V.H.). A data-extraction sheet was created a priori including author name, year of publication, study type, country, recruitment period, follow-up (months), total number of KTs performed in the period, number of patients aged ≤70 and >70 yr, age, body mass index, hypertension, diabetes, coronary disease, duration of dialysis prior to KT, dialysis modality, donor type, donor age, number of transplantations (first transplant or retransplant), Charlson Comorbidity Index (CCI), Karnofsky, Eastern Cooperative Oncology Group (ECOG), Clinical Frailty Scale, Frail Scale, cold ischaemia time (CIT), warm ischaemia time (WIT), operation time (minutes), GS, OS, DGF, PNF, creatinine level and eGFR, and complications according to the Clavien grading system.
In this SR, GS (noncensored for death) refers to the time from the date of transplantation to the date of irreversible graft failure signified by return to long-term dialysis (or retransplantation) or the date of the last follow-up during the period when the transplant was still functioning or the date of death.
2.4 Risk of bias assessment
Risk of bias assessment was performed independently (A.A. and A.D.) using the ROBINS-I tool for nonrandomised studies [
]. Study characteristics were extracted by one author, and a second author checked data extractions for accuracy. Any disagreements were resolved by discussion with a third author (V.H.). Since nonrandomised studies were included, this tool was extended with a list of important potential confounders established a priori by the YAU Kidney Transplantation Working Group. The confounders included were time on dialysis, donor type and age, and number of prior transplants. For each study, it was assessed whether each confounder was considered and whether, if necessary, the confounder was controlled for in the analysis.
2.5 Data synthesis
This review tabulates quantitative information and systematic descriptions of all studies included. Frequencies and percentages were used to report categorical variables; mean and standard deviation were used to report continuous variables. Measures of association were assessed using data reported in each study. Meta-analyses were conducted using studies with directly comparable groups, as determined by the existence of two categories (≤70 and >70 yr). Therefore, single-arm studies were excluded and only observational studies were included in meta-analysis, as there were no eligible randomised controlled studies with comparable groups. Relative risks (RRs) between two comparable groups were estimated using DerSimonian-Laird random-effect models. Heterogeneity was evaluated using the I2 statistic, and I2 thresholds of <25%, 25–49%, 50–75%, and >75% were considered to represent low, moderate, high, and very high heterogeneity, respectively. RRs and their 95% confidence intervals (CIs) were calculated and pooled with STATA v.15 (StataCorp, College Station, TX, USA). Statistical significance was defined as p < 0.05. Additionally, Egger linear regression and Begg’s test were used to examine publication bias. A p value of <0.05 was defined as a significant publication bias.
3. Evidence synthesis
3.1 Search results
The search retrieved 10 357 articles. After removing duplicates (n = 72), abstracts of 10 285 papers were screened. Of these, 10 186 were excluded and 99 met the abstract inclusion criteria. Finally, after full-text screening, a total of 19 studies were included (Fig. 1). In total, nine studies were included in the meta-analysis and pooled estimates were obtained for different outcomes: OS at 1 yr (four studies), 3 yr (three studies), 5 yr (five studies), and overall (six studies); GS at 1 yr (three studies), 3 yr (two studies), 5 yr (four studies), and overall (four studies); death with functioning graft (four pooled studies); DGF (six studies); graft loss (three studies); and acute rejection (AR; seven pooled studies).
Fig. 1PRISMA diagram. DGF = delayed graft function; GS = graft survival; KT = kidney transplant; OS = overall survival; PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-analyses; SR = systematic review.
3.2 Characteristics of studies, population, and interventions
The 19 studies included a total of 293 501 patients. Table 1 summarises baseline characteristics of both groups, with a total of 23 917 recipients aged >70 yr and 269 584 younger than 70 yr. Donor age was higher in the >70-yr group: 55.0 (45.4–77.0) versus 47.7 (39.0–71.6) yr. Furthermore, a higher number of expanded criteria donors (ECDs) in >70-yr recipients was identified (18.5% vs 2.7%). Regarding other potential confounders, time on dialysis was longer in the <70-yr group (37.0 vs 23.0 mo), while both groups had similar CIT (13.8 vs 13.3 h). The median follow-up for the >70-yr group was 50.9 mo (interquartile range [IQR] 38.8–72.7) and 64.2 mo (IQR 47.0–72.0) in the <70-yr group.
Table 1Baseline characteristics of population receiving a kidney transplant (KT) in the included studies stratified by age (>70 and <70 yr)
>70 yr
<70 yr
N = 293 501
23 917
269 584
Age (yr), median (range)
73.5 (70.3–81.6)
57.4 (46.4–67.2)
Donor age (yr), median (range)
55.0 (45.4–77.0)
47.7 (39.0–71.6)
Follow-up (yr), median (range)
50.9 (38.8–72.7)
64.2 (47.0–72.0)
BMI
26.5 (25.5–28.0)
27.4 (26.3–29.0)
Hypertension, % (n)
28.1% (3122/11 102)
3.6% (5285/147 786)
Diabetes, % (n)
20.0% (4556/22 734)
13.7% (36 145/264 555)
Coronary disease, % (n)
9.4% (1477/15 759)
3.4% (6254/183 035)
Time on dialysis prior to KT (mo), median (range)
23.0 (6.2–47.7)
37.0 (6.9–64.1)
Type of dialysis, % (n)
Haemodialysis
67.0 (817/1219)
82.2 (37/45)
Peritoneal
15.8 (193/1219)
17.8 (8/45)
Type of donor, % (n)
LD
27.3 (6340/23 239)
35.0 (93 249/266 419)
DBD
46.4 (5009/10797)
18.5 (21 163/114 490)
ECD
18.5 (3575/19 638)
2.7 (6824/256 417)
DCD
4.3 (582/13 546)
2.1 (2581/123 511)
Number of KT, % (n)
1st
98.7 (17402/17 638)
91.1 (114 311/125 431)
Retransplant
1.3 (236/17 638)
8.9 (11 120/125 431)
CIT (h), median (range)
13.8 (2.0–26.0)
13.3 (2.2–24.9)
WIT (min), median (range)*
51.2
48.0
BMI = body mass index; CIT = cold ischaemia time; DBD = donor after brain death; DCD = donor after cardiocirculatory death; ECD = expanded criteria donor; LD = living donor; WIT = warm ischaemia time.
] published the study including the largest number of patients (298 455). Eleven comparative studies (ten retrospective and one prospective) were included, while the remaining eight were case series (>70 yr).
A quantitative analysis (meta-analysis) was performed to pool and compare outcomes between both groups. Figure 2 represents the forest plot of the pooled RR for OS. The pooled meta-analysis showed a significant decrease in 5-yr OS in patients aged >70 yr (RR: 1.66; 95% CI: 1.18–2.35). A significant difference between both groups was also observed at 1 yr (RR: 1.98; 95% CI: 1.34–2.93) and 3 yr (RR: 2.17; 95% CI: 1.61–2.93) of follow-up.
Fig. 2Forest plots of the pooled RRs for OS at (A) the mean follow-up, and (B) 5 yr, (C) 3 yr, and (D) 1 yr of follow-up. There was worst OS at all time points in the >70-yr group (RR, 1.66; 95% CI, 1.18–2.35; p = 0.003). CI = confidence interval; OS = overall survival; RR = relative risk.
Five-year GS ranged from 51.0% to 93.1% in the elderly (>70 yr) versus 68.0 to 94.0% in the younger group (<70 yr). Table 3 contains the survival outcomes of the included studies, and Figure 3 shows the forest plot of the pooled RRs for GS. There was significantly better 5-yr GS in recipients aged <70 yr (RR, 1.37; 95% CI, 1.14–1.65), without significant differences in short term. The pooled RR of GS was 1.18 (95% CI, 0.79–1.75) at 1 yr and 1.33 (95% CI, 0.94–1.87) at 3 yr.
Table 3Survival outcomes in percentage of population receiving a kidney transplant (KT)
Fig. 3Forest plots of the pooled RRs for graft survival (GS) at (A) the mean follow-up, and (B) 5 yr, (C) 3 yr, and (D)1 yr of follow-up. There was worst GS since 5-yr time point in the >70-yr group (RR, 1.37; 95% CI, 1.14–1.65; p = 0.334). CI = confidence interval; GS = graft survival; RR = relative risk.
] did it according to the Clavien-Dindo classification system, without complications Clavien >III in both groups.
3.4 Secondary outcomes
Figure 4 shows the forest plot of the pooled RR for DGF, AR, death with functioning graft, and graft loss.
Fig. 4Forest plots of the pooled RRs for (A) DGF (B) acute rejection, (C) death with functioning graft, and (D) graft loss. There were no worse outcomes in the >70-yr group for any secondary endpoint. CI = confidence interval; DGF = delayed graft function; RR = relative risk.
DGF rates ranged from 19.4% to 53.6% in elderly recipients (>70 yr) and from 18.1% to 60.0% in younger ones (<70 yr; Table 4), without significant differences between both groups (RR, 1.08; 95% CI, 0.86–1.36).
Table 4Comparative functional outcomes and complications of KT recipients according to study groups (<70- and >70-yr old)
Three comparative studies reported the graft loss rate. It ranged from 9.3% to 38.5% in the older group versus 14.3% to 37.4% in the younger group, without reaching statistical significance (RR, 0.95; 95% CI, 0.61–1.48).
Regarding AR, it is the most frequently reported indicator among comparatives studies (seven studies included in meta-analysis). In recipients aged >70 yr, rejection rates range from 4.3% to 40.0%, while in the younger group the rates are 4.7–50%. The pooled analysis showed no increased likelihood of AR in >70-yr old patients (RR, 0.87; 95% CI, 0.80–0.93).
Only two studies reported PNF rates. Huang et al. [
]. Figure 5 includes the traffic-light plot for the risk of bias domains in ROBINS-I tool for the 11 comparative studies included in this SR. Most of the studies exhibited a moderate or high risk of bias according to this tool. Neither Egger’s nor Begg’s test demonstrated a significant publication bias across the articles included in the meta-analysis for any endpoint (p > 0.05; Supplementary material).
Fig. 5“Risk of bias” assessment for each included study. D1 = confounding; D2 = selection of participants; D3 = classification of interventions; D4 = deviations from intended interventions; D5 = missing data; D6 = measurement of outcomes; and D7 = selection of the reported result.
3.6.1 Findings in the context of existing literature
This SR and meta-analysis highlight a gap in knowledge and research regarding outcomes of KT in older population. Along with the growing pool of elderly KT recipients, several large studies assessing KT outcomes in these patients have been published over recent years. In this scenario, it is crucial to determine outcomes and to select which patients may benefit from KT and who are at a high risk of post-transplant complications. With that purpose, we conducted this SR including a large number of recipients, which contributes to widen the evidence about this renal replacement therapy in this vulnerable population.
Regarding primary objectives, elderly (>70 yr) recipients have worse OS at all time points (Fig. 2), while GS remains comparable with that for young recipients (<70 yr) in the short term (1 and 3 yr) but becomes worse in the long term (5 yr and end of follow-up; Fig. 3). Complication rates, a relevant primary objective of the present study, were under-reported and so could not be analysed properly.
Concerning secondary objectives, the elderly group did not have worse DGF, AR, death with functioning graft, or graft loss (Fig. 4).
3.6.2 Ageing and KT
It has been estimated that by 2030, 60% of patients with chronic kidney disease needing renal replacement therapy will be older than 65 yr [
Dialysis or kidney transplantation in older adults? A systematic review summarizing functional, psychological, and quality of life-related outcomes after start of kidney replacement therapy.
]. However, at advanced ages, a decision between dialysis and KT can be difficult mainly due to comorbidities and geriatric syndromes such as cognitive impairment or frailty [
Dialysis or kidney transplantation in older adults? A systematic review summarizing functional, psychological, and quality of life-related outcomes after start of kidney replacement therapy.
Elderly population is a heterogeneous group. Medical research commonly defines people as elderly when they are aged 65 yr or above. Nevertheless, defining elderly age by chronology alone has its limitations [
]. Variability among elderly definitions depends on the life expectancy variations experienced by the population during the past decades. Indeed, a geriatric patient is not specifically age defined but rather characterised by a high degree of frailty and multiple active diseases that become more common in the age group above 80 yr, according to the Geriatric Medicine Section of the European Union of Medical Specialists [
]. In this SR, the limit of 70 yr was established by the YAU Kidney Transplantation Working Group, trying to present updated research adapted to developed countries’ demography. In fact, and according to the Eurostat Report [
], in 2020, the life expectancy at birth in the EU was 80.4 yr. Furthermore, considering the mean age of KT recipients in our context as developed countries, in Spain, the proportion of >70-yr-old recipients transplanted has been increasing constantly during the past decade, reaching 19.2% in 2021 [
], who encountered that these recipients represented 18.4% of the transplanted population, a five-fold rise from 3.4% in 1990s.
To avoid a bias due to the differences between heterogeneous groups, an age-stratified analysis of outcomes, mainly survival, should ideally be performed. Nevertheless, preliminary search revealed a lack of papers analysing similar age subgroups. Recently, Vanhove et al. [
] assessed outcomes in first-time single KT recipients through multistate models and encountered that in the elderly (>75 yr), the absolute overestimation of death risk with functioning graft was four-fold higher than in the <55-yr group, concluding that these multistate models provide a comprehensive assessment of KT outcomes, particularly in older recipients, who are more prone to event rate overestimation and for whom outcomes after graft failure are worse than for younger population.
Dialysis or kidney transplantation in older adults? A systematic review summarizing functional, psychological, and quality of life-related outcomes after start of kidney replacement therapy.
] assessing QoL outcomes of renal replacement therapies, these improve in the majority of the older KT recipients and were superior to dialysis. Moreover, functional status was worse, and the incidence of serious fall injuries increased in many older dialysis patients.
Dialysis patients have 10–20 times higher cardiac mortality rates than the general population, and although this risk is lessened after transplant, patients carry the burden of their time spent living with ESRD and on dialysis, and cardiac mortality rates remain high. According to Wyld et al. [
], of 5089 deaths in 16 329 KT recipients, 18% were cardiac: older age, longer dialysis duration, and earlier era of transplantation were associated with this outcome.
3.6.4 The use of frailty and comorbidity scores
Based on the Consensus Guidelines of the Canadian Society of Transplantation, advanced age per se is not a contraindication for KT, so older patients with ESRD without medical or surgical contraindications should be considered candidates [
Defining the ethical considerations surrounding kidney transplantation for frail and cognitively impaired patients: a Delphi study of geriatric transplant experts.
Kidney transplantation outcome predictions (KTOP): a risk prediction tool for kidney transplants from brain-dead deceased donors based on a large European cohort.
]. In this context, a refined assessment of elderly patients who are candidates for KT might be performed. Potential elderly recipients must be assessed precisely to exclude serious cardiovascular disease, cancer, and other comorbidities. Some indicators have been proposed to improve candidate selection. According to a recent SR, frailty is associated with higher rates of DGF and length of stay [
]. In Table 1, we can observe higher percentages of hypertension (28.1% vs 3.6%), diabetes (20.0% vs 13.7%), and coronary disease (9.4% vs 3.4%) rates in elderly patients. The CCI can be used to describe comorbidities in patients who are going to receive an intervention such as KT, but it has not proved its usefulness predicting mortality in the population age >70 yr [
]. In this SR, an attempt was made to extract data regarding frailty and comorbidity scales (CCI, Karnofsky, ECOG, Clinical Frailty Scale, and Frail Scale), but no paper except that of Heldal et al. [
] reported any information. Given the expected demographic evolution in developed countries, it would be advisable to include geriatric assessments using tools such as those mentioned above to refine recipient selection and to be able to predict complications.
3.6.5 Heterogeneous outcomes
Over the past decades, many studies in developed countries have reported outcomes of KT in elderly patients, assessing patient’s risks and determining the age effect on GS. However, consensus has not been reached, although its safety has been reported in selected elderly patients [
]. Data are somewhat heterogeneous, mainly due to different age thresholds and nonstandardised data regarding KT outcomes, particularly from a surgical point of view. According to the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry Study, with 10 651 recipients, elderly people may have inferior OS and GS [
]. On the contrary, other researchers have published encouraging data, with lower rejection rates and better GS, although with inferior OS because of higher cardiovascular risk factors [
]. Improved OS and GS with current immunosuppressive protocols have broadened the application of KT to selected elderly patients, and a rising number of patients aged >65 yr are receiving transplants [
]. Moreover, recipient’s preoperative optimisation as well as effective and safe anaesthesia during KT and postoperative care contributes to successful outcomes [
In the present SR, 5-yr GS ranged from 51.0% to 93.1% in >70-yr and from 68.0% to 94.0% in <70-yr old recipients, with pooled RRs of 1.37 (95% CI, 1.14–1.65; I2 11.8%, p = 0.334) at 5 yr and 1.54 (95% CI, 1.13–2.11; I2 95.6%, p = 0.000) at the end of follow-up (Fig. 3). Concerning patient survival, there was significantly lower OS at all time points in the >70-yr group (at 5 yr of follow-up: RR, 1.66; 95% CI, 1.18–2.35; I2 75.4%, p = 0.003; Fig. 2). Although probably explained in part by age, this finding makes it necessary to be cautious when deciding to go for KT in elderly patients.
In the current meta-analysis, the pooled RR for graft loss rates was 0.95 (0.61–1.48, p = 0.000; Fig. 4). In this sense, it seems to be constant throughout literature that similar AR and graft loss rates are described between older and younger recipients; Molnar et al. [
] reported a graft loss rate of 9.4% in elderly recipients compared with 14.3% in younger recipients. Regarding other functional outcomes, results from the meta-analysis indicate that there was not a significant difference in DGF between both groups (RR, 1.08; 95% CI, 0.86–1.36; p = 0.0000). The largest study reporting DGF rates by Doucet et al. [
]. Extracted outcomes were quite similar between both groups: median eGFR at the last follow-up was 47.1 ml/min in the >70-yr control group versus 48.0 ml/min in the younger group, while the median creatinine level was 1.76 (range 1.5–2.0) versus 1.8 (range 1.7–1.9) mg/dl in the >70-yr versus <70-yr group.
3.6.6 Surgical risk and postoperative complications
Older recipients are usually at a greater risk of perioperative complications, including death, mainly due to infection and cardiovascular disease [
]. However, a lack of reported data about postoperative complications has been identified, particularly from a surgical point of view. Urinary leak (10.1%, 14/138) or surgical site infection rates (18.8%, 26/138) have been reported only in one study for older patients [
], and this condition can make surgery very challenging. Vascular complication rates have been described poorly in the studies included in this SR—only in two comparative studies [
]). Furthermore, since retransplant rates have increased drastically to almost 25% over the past decades, this issue represents a challenge, especially in elderly population that could potentially need a subsequent KT [
]. However, the retransplant rate in this group is lower.
Concerning WIT, which is directly related to surgical complexity, only one study addressed this parameter. WIT in the <70-yr group was 48.0 versus 52.6 min in the >70-yr group [
]. Another indicator of surgical complexity is the number of prior transplants. Retransplant rate, understood as the proportion of patients undergoing subsequent transplants after graft failure, was significantly lower in the >70-yr group (1.3% vs 8.9% in the <70-yr group; Table 1). This fact probably reflects a more meticulous selection of elderly recipients when considering a potential KT, which undoubtedly introduces a bias that should lead us to a cautious interpretation of the outcomes for this old-age group.
3.6.7 Donor selection
In many KT programmes, transplantation teams attempt to match by allocating ECD organs to older recipients. Compared with organs from standard criteria donors, ECD kidneys are associated with worse GS outcomes, but with increased life expectancy over dialysis in older recipients [
]. This effect of donor age poses a major confounder in the assessment of KT outcomes in elderly population when comparing with younger cohorts. Thus, as represented in Table 1, donor age was higher in the >70-yr group (55.0 vs 47.7 in the <70-yr group), with a higher proportion of ECDs (18.5% vs 2.7%), a higher proportion of donors after cardiocirculatory death (4.3% vs 2.1%), and a lower proportion of living donors (27.3% vs 35.0%).
3.6.8 Strengths and limitations
Several limitations of the present SR need to be mentioned. The first and main limitation was the difficulty for determining a homogeneous age threshold, as there are no standardised cut-offs in the literature, where these range from >60 yr in the 1990s’ studies to >80 yr in the most recent studies. Moreover, most of the papers about old population lack a geriatric assessment and/or frailty or comorbidity scores. In addition, the existence of studies analysing patients from US nationwide databases in different periods may lead to duplicated populations. Lastly, some confounders such as donor features or time on dialysis have not been controlled.
However, to our knowledge, this work has several strengths. Its relevance, according to demographic evolution in developed countries, makes it of great interest to transplant and urological communities, as it reports outcomes about the real population that we will have to face over the next years. Furthermore, it reports outcomes and meta-analyses of a very large number of transplanted patients, highlighting the potential need of geriatric or frailty assessment and stressing the importance of reporting surgical complications as an important part of KT outcomes, particularly in this old-age setting where it becomes even more relevant when selecting potential candidates.
4. Conclusions
Elderly KT recipients (>70 yr) have worse OS at all time points and long-term GS compared with younger recipients (<70 yr). Postoperative complications were under-reported and could not be assessed. The DGF, AR, death with functioning graft, and graft loss in elderly population were not inferior to those in younger population. Considering progressive and constant ageing of population in developed countries, the addition of geriatric assessment in this setting might be useful for selecting better elderly candidates for KT.
Author contributions: Vital Hevia had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Territo, Hevia, Campi, Boissier, Prudhomme, Pecoraro.
Acquisition of data: Artiles, Domínguez, Subiela, Hevia.
Analysis and interpretation of data: Artiles, Domínguez, Subiela, Hevia.
Drafting of the manuscript: Artiles, Domínguez, Subiela, Hevia.
Critical revision of the manuscript for important intellectual content: Artiles, Domínguez, Subiela, Hevia, Burgos, Breda, Territo, Campi, Boissier, Prudhomme, Pecoraro.
Administrative, technical, or material support: Artiles, Domínguez, Subiela.
Supervision: Hevia, Territo.
Other: None.
Financial disclosures: Vital Hevia certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: None.
Funding/Support and role of the sponsor: None.
Appendix A. Supplementary data
The following are the Supplementary data to this article:
Dialysis or kidney transplantation in older adults? A systematic review summarizing functional, psychological, and quality of life-related outcomes after start of kidney replacement therapy.
Defining the ethical considerations surrounding kidney transplantation for frail and cognitively impaired patients: a Delphi study of geriatric transplant experts.
Kidney transplantation outcome predictions (KTOP): a risk prediction tool for kidney transplants from brain-dead deceased donors based on a large European cohort.
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