The relationship of donor source and age on short- and long-term allograft survival in pediatric renal transplantation

Risk Factor Analysis for Long-Term Graft Survival Following Pediatric Kidney Transplantation: The Importance of Pretransplantation Time on Dialysis and Donor/Recipient Age Difference

Recognizing risk factors that may negatively affect long-term graft survival following pediatric kidney transplantation is a key element in the decision-making process during organ allocation. We retrospectively reassessed all cases of pediatric kidney transplantation performed in our center in the last 20 years with the aim of determining baseline characteristics that could be identified as prognostic risk factors for long-term graft survival. Between 2001 and 2020, a total of 91 kidney transplantations in children under the age of 18 years were undertaken in our center. Early graft failure was observed in six of the 91 patients (7%). The median follow-up of the remaining 85 children was 100 months, and the overall kidney graft survival rates at 5, 10, 15 and 20 years were 85.2%, 71.4%, 46.0% and 30.6%, respectively. Small children with a body surface area of <1 m2 were significantly associated with better long-term graft survival outcomes, while adolescents aged more than twelve years showed poorer graft survival rates than younger children. Body surface area of the recipient of ≥1 m2, pretransplantation duration of the recipient on dialysis ≥18 months, hemodialysis prior to transplantation and donor/recipient age difference of ≥25 years were significantly associated with poorer long-term graft survival.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Synthesizing external aggregated information in the penalized Cox regression under population heterogeneity

Synthesizing external aggregated information has been proven useful in improving estimation efficiency when conducting statistical analysis using a limited amount of data. In this paper, we develop a unified framework for combining information from high-dimensional individual-level data and potentially low-dimensional external aggregate data under the Cox model. We summarize various forms of external aggregated information by population estimating equations and propose a penalized empirical likelihood approach to borrow information from these estimating equations. The proposed methods possess the flexibility to handle the case where individual-level data and external aggregate data are from heterogeneous populations. Specifically, a penalized empirical likelihood ratio test is developed to check for the potential heterogeneity, and a semiparametric density ratio model is postulated to account for the heterogeneity. Moreover, we study the impact of uncertainty in the auxiliary information on the efficiency gain and propose a modified variance estimator to adjust for the uncertainty. The proposed estimators enjoy the oracle property and are asymptotically more efficient than the penalized partial likelihood estimator that does not exploit the external aggregated information. Simulation studies show improvement in both estimation efficiency and variable selection over the competitors. The proposed approaches are applied to the analysis of a pediatric kidney transplant study for illustration.

Prognostic Factors on Graft Function in Pediatric Kidney Recipients

BACKGROUND

Graft survival in pediatric kidney transplant recipients has increased in the last decades. Determining prognostic factors for graft function over time allows the identification of patients at risk for graft loss and could lead to improvement of current guidelines.

METHODS

Data were collected among pediatric kidney transplant recipients in a single center during the first 5 years after transplantation. Mixed model analysis was used to indicate possible prognostic factors for the loss of graft function.

RESULTS

A total of 100 pediatric kidney transplant recipients were analyzed. Negative prognostics of graft function are higher donor age and higher recipient age, presence of obstructive uropathology, re-transplant, and occurrence of BK viremia. The negative influence on graft function of both donor age and presence of obstructive uropathology increased over time. In this study, the factors that did not influence graft function over time were the number of HLA mismatches, pre-transplant dialysis, intra-abdominal graft placement, ischemia time, occurrence of acute rejection, presence of lower urinary tract dysfunction, occurrence of urinary tract infections, and infections with cytomegalovirus and Epstein-Barr virus.

CONCLUSIONS

This study showed that a higher donor age and higher recipient age, presence of obstructive uropathology, a re-transplant, and the occurrence of BK viremia were negative prognostic factors of graft function over time, in the first 5 years after transplant. Graft function was comparable between steroid-sparing regimens (preferable in low-risk patients) and regimens including steroids (for special reasons).

The "oldest and coldest" shipped living donor kidneys transplanted through kidney paired donation

To date, thousands of living donor kidneys have been shipped through kidney paired donation (KPD). To expand on this growing segment of living donor transplantation, we evaluated the effect of advanced age donation ("oldest kidneys") and prolonged cold ischemia time ("coldest kidneys") on graft function and survival using the National Kidney Registry database from February 2008 to May 2018. Donors were stratified by age at time of donation (<65 or ≥65 years) and kidneys were stratified by cold ischemia time (<16 or ≥16 hours). We evaluated delayed graft function and death-censored graft failure (DCGF) for up to seven posttransplant years. Of the 2363 shipped living donor kidney transplants, 4.1% of donors were ≥65 years and 6.0% of transplanted kidneys had cold ischemia times ≥16 hours. Delayed graft function and DCGF occurred in 5.2% and 4.7% of cases. There were no significant associations between delayed graft function and donor age (P = .947) or cold ischemia (P = .532). Donor age and cold ischemia time were not predictive of delayed graft function (OR = 0.86,1.20; P = .8, .6) or DCGF (HR = 1.38,0.35, P = .5, .1). These findings may alleviate concerns surrounding the utilization of kidneys from older donors or those originating from distant transplant centers.

The role of CD47 in pathogenesis and treatment of renal ischemia reperfusion injury

Ischemia reperfusion (IR) injury is a process defined by the temporary loss of blood flow and tissue perfusion followed later by restoration of the same. Brief periods of IR can be tolerated with little permanent deficit, but sensitivity varies for different target cells and tissues. Ischemia reperfusion injuries have multiple causes including peripheral vascular disease and surgical interventions that disrupt soft tissue and organ perfusion as occurs in general and reconstructive surgery. Ischemia reperfusion injury is especially prominent in organ transplantation where substantial effort has been focused on protecting the transplanted organ from the consequences of IR. A number of factors mediate IR injury including the production of reactive oxygen species and inflammatory cell infiltration and activation. In the kidney, IR injury is a major cause of acute injury and secondary loss of renal function. Transplant-initiated renal IR is also a stimulus for innate and adaptive immune-mediated transplant dysfunction. The cell surface molecule CD47 negatively modulates cell and tissue responses to stress through limitation of specific homeostatic pathways and initiation of cell death pathways. Herein, a summary of the maladaptive activities of renal CD47 will be considered as well as the possible therapeutic benefit of interfering with CD47 to limit renal IR.

A donor risk index for graft loss in pediatric living donor kidney transplantation

Pediatric kidney transplant candidates often have multiple potential living donors (LDs); no evidence-based tool exists to compare potential LDs, or to decide between marginal LDs and deceased donor (DD) kidney transplantation (KT). We developed a pediatric living kidney donor profile index (P-LKDPI) on the same scale as the DD KDPI by using Cox regression to model the risk of all-cause graft loss as a function of living donor characteristics and DD KDPI. HLA-B mismatch (adjusted hazard ratio [aHR] per mismatch = 1.04 1.271.55 ), HLA-DR mismatch (aHR per mismatch = 1.02 1.231.49 ), ABO incompatibility (aHR = 1.20 3.268.81 ), donor systolic blood pressure (aHR per 10 mm Hg = 1.01 1.071.18 ), and donor estimated GFR (eGFR; aHR per 10 mL/min/1.73 m2 = 0.88 0.940.99 ) were associated with graft loss after LDKT. Median (interquartile range [IQR]) P-LKDPI was -25 (-56 to 12). 68% of donors had P-LKDPI <0 (less risk than any DD kidney) and 25% of donors had P-LKDPI >14 (more risk than median DD kidney among pediatric KT recipients during the study period). Strata of LDKT recipients of kidneys with higher P-LKDPI had a higher cumulative incidence of graft loss (39% at 10 years for P-LDKPI ≥20, 28% for 20> P-LKDPI ≥-20, 23% for -20 > P-LKDPI ≥-60, 19% for P-LKDPI <-60 [log rank P < .001]). The P-LKDPI can aid in organ selection for pediatric KT recipients by allowing comparison of potential LD and DD kidneys.

Good long-term renal graft survival and low incidence of cardiac pathology in adults after short dialysis period and renal transplantation in early childhood - a cohort study

Over the past 30 years, there has been an improvement in both patient and graft survival after pediatric renal transplantation (RTX). Despite this success, these patients still carry an elevated risk for untimely death, partly through premature aging of the vasculature. The aim of this study was thus to investigate the long-term outcome of individuals with RTX in childhood, as well as to explore the cardiovascular health of these adults more than a decade later. We studied 131 individuals who had undergone a RTX between the years 1979 and 2005. Furthermore, left ventricular hypertrophy (LVH), coronary artery calcifications (CAC), and related metabolic factors were investigated in a cross-sectional study including 52 individuals as part of the initial cohort. The mortality rate (n = 131) was 12.2%. The median estimated graft survival was 17.5 years (95% CI 13.6-21.3), being significantly better in children transplanted below the age of 5 years (18.6 vs. 14.3 years, P < 0.01) compared with older ones. CAC were found in 9.8% and LVH in 13% of the patients. Those with cardiac calcifications had longer dialysis vintage and higher values of parathyroid hormone (PTH) during dialysis. Left ventricular mass correlated positively with systolic blood pressure, PTH, and phosphate measured at the time of the study.

Parents' experiences of donation to their child before kidney transplantation: A qualitative study

AIM AND OBJECTIVES

To explore parents' experiences of donation to their child before kidney transplantation.

BACKGROUND

Transplantation is the treatment of choice for paediatric patients with end-stage renal disease. Living donor kidney transplantation has shown a higher long-term transplant survival compared to deceased donor transplantation and entails a more controllable process, with shorter waiting time. Besides complex care and treatment of their child, parents must reflect on the prospects of being a donor for their child. However, little is known about the parent donor and parent caregiver perspective.

DESIGN

A qualitative exploratory study taking a phenomenological-hermeneutic approach.

METHOD

The study was conducted in a Danish university hospital. Interviews were conducted with the parents of seven children, aged between 5-15 years, with end-stage renal disease in the period before kidney transplantation. Data were analysed with inspiration from Ricoeur's theory of interpretation on three levels: naïve reading, structural analysis and critical interpretation and discussion.

RESULTS

The decision about donation was experienced as a matter of course and commitment. There were preferences for a kidney from a living donor, including the hope of being accepted as a donor. Being refused as a donor revealed feelings of powerlessness. However, transformation was performed into having a new role providing care and comfort to the child during the transplant process. Asking family and friends about donation could feel like crossing a line.

CONCLUSION

The prospect of donating to one's child had an impact on the well-being of the entire family. Parents were in a vulnerable situation and in need of support, regarding both living and deceased donation. Waiting time included hopeful thoughts and reflections on a new caregiver role for the child during transplantation.

RELEVANCE TO CLINICAL PRACTICE

Health professionals' attention, engagement and dialogue are essential in order to gain extensive and varied knowledge about the individual parent's experiences and the well-being of the entire family to provide care and support before, during and after the donation and transplantation process.

The impact of donor/recipient age difference and HLA mismatch on graft outcome in pediatric kidney transplantation

BACKGROUND

Understanding the relationship between the factors that influence long-term kidney transplant survival remains a key priority for pediatric nephrologists. We assessed the relative impact of donor/recipient age difference and HLA matching on long-term graft outcomes.

METHODS

We conducted a retrospective cohort study of pediatric and adolescent recipients who received a primary kidney transplant in Australia and New Zealand between January 1, 1990, and December 31, 2015. The primary outcome was graft survival analyzed by Kaplan-Meier method.

RESULTS

During the 26-year period, 1134 primary (395 DD and 739 LD) kidney transplants were performed in recipients less than 20 years of age. The median follow-up time was 10.2 years. Overall, 405 patients (35.7%) lost their transplant with graft survival 93.8% at 1 year, 82.5% at 5 years, 65.8% at 10 years, and 49.9% at 15 years post-transplant. There was consistently higher graft loss of DD kidneys as compared to LD kidneys at each time point. Both increasing donor/recipient age difference (aHR 1.11 per 10 years; 95% CI, 1.02-1.20; P = 0.009) and increasing HLA mismatch (aHR 1.20 per mismatch; 95% CI, 1.10-1.30; P < 0.001) were associated with decreased graft survival.

CONCLUSIONS

Donor/recipient age difference and HLA matching are important factors influencing long-term graft outcomes in pediatric kidney transplantation. HLA mismatch remains a strong predictor of graft loss. For patients without the option of a LD, we suggest that the degree of HLA mismatch should not be discounted as part of the decision-making process of organ allocation.

Pediatric Renal Transplantation: Evaluation of Long-Term Outcomes and Comparison to Adult Population

BACKGROUND

In Europe, pediatric transplantation accounts for only about 4% of all kidney transplantations performed. The aim of our work is to evaluate the evolution of pediatric renal transplantation in our department over time, but also to compare this special population with the adult one.

METHODS

We evaluated all pediatric renal transplantations performed in our department between January 1981 and December 2016. We performed the analysis of clinical, analytical, and surgical factors to look for predictive factors of graft loss or decrease of survival. In addition, we performed a comparative study of pediatric and adult populations and an evaluation of the evolution of pediatric renal transplantation in our department over time.

RESULTS

We evaluated 101 renal transplantations performed in patients younger than 18 years. Pediatric transplantations corresponded to 3.4% of all renal transplantations performed in our department. The rate of living donors was 12%. Donors of grafts for the pediatric population were significantly younger than in the adult population. The increase in donor age was associated with lower renal graft survival rates. Acute rejections were more frequent in the pediatric population. Eleven pediatric recipients (10.9%) died in the follow-up period. Renal graft survival in the pediatric population was 94.8%, 77.4%, and 66.5% at 1, 5, and 10 years, respectively. There was no significant difference in graft survival in the pediatric and adult population. The pediatric overall survival rate at 1, 5 and 10 years was 97.9%, 96.8%, and 91.9%, respectively.

CONCLUSION

Pediatric renal transplantation presents results identical to those identified in adults.

Outcome of renal transplantation in small infants: a match-controlled analysis

BACKGROUND

Infants with a body weight of less than 10 kg are often not considered to be suitable candidates for renal transplantation (RTx). The objective of this study was to evaluate this arbitrary weight threshold for pediatric RTx.

METHODS

We conducted a multicenter, retrospective, match-controlled cohort study on infants weighing less than 10 kg at time of engrafting (low-weight group [LWG], n = 38) compared to a matched control group (n = 76) with a body weight of 10-15 kg, using data from the first 2 years post-transplant derived from the CERTAIN Registry.

RESULTS

Patient survival was 97 and 100% in the LWG and control groups, respectively (P = 0.33), and death-censored graft survival was 100 and 95% in the LWG and control groups, respectively (P = 0.30). Estimated glomerular filtration rate at 2 years post-transplant was excellent and comparable between the groups (LWG 77.6 ± 34.9 mL/min/1.73 m²; control 74.8 ± 29.1 mL/min/1.73 m²; P = 0.68). The overall incidences of surgery-related complications (LWG 11%, control 23%; P = 0.12) and medical outcome measures (LWG 23%, control 36%, P = 0.17) were not significantly different between the groups. The medical outcome measures included transplant-related viral diseases (LWG 10%, control 21%; P = 0.20), acute rejection episodes (LWG 14%, control 29%; P = 0.092), malignancies (LWG 3%, control 0%; P = 0.33) and arterial hypertension (LWG 73%, control 67%; P = 0.57).

CONCLUSIONS

These data suggest that RTx in low-weight children is a feasible option, at least in selected centers with appropriate surgical and medical expertise.

The association of donor and recipient age with graft survival in paediatric renal transplant recipients in a European Society for Paediatric Nephrology/European Renal Association-European Dialysis and Transplantation Association Registry study

Background

The impact of donor age in paediatric kidney transplantation is unclear. We therefore examined the association of donor-recipient age combinations with graft survival in children.

Methods

Data for 4686 first kidney transplantations performed in 13 countries in 1990-2013 were extracted from the ESPN/ERA-EDTA Registry. The effect of donor and recipient age combinations on 5-year graft-failure risk, stratified by donor source, was estimated using Kaplan-Meier survival curves and Cox regression, while adjusting for sex, primary renal diseases with a high risk of recurrence, pre-emptive transplantation, year of transplantation and country.

Results

The risk of graft failure in older living donors (50-75 years old) was similar to that of younger living donors {adjusted hazard ratio [aHR] 0.74 [95% confidence interval (CI) 0.38-1.47]}. Deceased donor (DD) age was non-linearly associated with graft survival, with the highest risk of graft failure found in the youngest donor age group [0-5 years; compared with donor ages 12-19 years; aHR 1.69 (95% CI 1.26-2.26)], especially among the youngest recipients (0-11 years). DD age had little effect on graft failure in recipients' ages 12-19 years.

Conclusions

Our results suggest that donations from older living donors provide excellent graft outcomes in all paediatric recipients. For young recipients, the allocation of DDs over the age of 5 years should be prioritized.

Clinical Outcomes in Pediatric Renal Transplant Recipients Who Received Steroid-Based Immunosuppressive Regimen

BACKGROUND

Although the clinical outcomes of pediatric renal transplantation (RT) in developed countries have improved significantly, the data on clinical outcomes in developing countries are wildly different.

METHODS

Children and adolescents who had undergone RT at Ramathibodi Hospital between March 2001 and August 2014 were included.

RESULTS

Patients were divided into 2 groups: living related donor (LRD) group (n = 13) and deceased donor (DD) group (n = 30). Prolonged cold ischemic time over 13 hours was significantly associated with delayed graft function (P = .029). The prevalence of infection was 90.7%, in which urinary tract infection (UTI) was the most common infection. Although almost none of the patients in the LRD group received induction therapy, the prevalence of rejection was not significantly different between the 2 groups (P = .817). The comparison of graft survivals between LRD and DD groups were 100% vs 100%, 92.3% vs 100%, and 85.7% vs 81.8% at 1, 3, and 5 years, respectively (P = .938). Recurrent UTI and cytomegalovirus (CMV) infection had a negative effect on graft function at 1-year follow-up (P < .05). Rejections, bladder dysfunction, and donors aged ≥50 years were associated with graft deterioration at 3 years after RT (P < .01). None of these patients died with functioning graft.

CONCLUSION

This study demonstrated good graft and patient survival in Thai pediatric RT recipients. Although recurrent UTI and CMV infection were related to graft dysfunction at 1-year follow-up, infections had no effect on graft and patient survival in long-term follow-up.

Pediatric kidney transplantation

Since first performed in 1954, kidney transplantation has evolved as the preferred long-term treatment of children with end stage renal disease (ESRD). The etiology of chronic kidney disease (CKD) and ESRD in children is broad and can be quite complicated, necessitating a multidisciplinary team to adequately care for these patients and their myriad needs. Precise surgical techniques and modern protocols for immunosuppression provide excellent long-term patient and graft survival. This article reviews the many etiologies of renal failure in the pediatric population focusing on those most commonly leading to the need for kidney transplantation. The processes of evaluation, kidney transplantation, short-term and long-term complications, as well as long-term outcomes are also reviewed.

Balancing competing needs in kidney transplantation: does an allocation system prioritizing children affect the renal transplant function?

Children often merit priority in access to deceased donor kidneys by organ-sharing organizations. We report the impact of the new Swiss Organ Allocation System (SOAS) introduced in 2007, offering all kidney allografts from deceased donors <60 years preferentially to children. The retrospective cohort study included all paediatric transplant patients (<20 years of age) before (n = 19) and after (n = 32) the new SOAS (from 2001 to 2014). Estimated glomerular filtration rate (eGFR), urine protein-to-creatinine ratio (UPC), need for antihypertensive medication, waiting times to kidney transplantation (KTX), number of pre-emptive transplantations and rejections, and the proportion of living donor transplants were considered as outcome parameters. Patients after the new SOAS had significantly better eGFRs 2 years after KTX (Mean Difference, MD = 25.7 ml/min/1.73 m² , P = 0.025), lower UPC ratios (Median Difference, MeD = -14.5 g/mol, P = 0.004), decreased waiting times to KTX (MeD = -97 days, P = 0.021) and a higher proportion of pre-emptive transplantations (Odds Ratio = 9.4, 95% CI = 1.1-80.3, P = 0.018), while the need for antihypertensive medication, number of rejections and living donor transplantations remained stable. The new SOAS is associated with improved short-term clinical outcomes and more rapid access to KTX. Despite lacking long-term research, the study results should encourage other policy makers to adopt the SOAS approach.

Long-term outcome of pediatric kidney transplantation: A single-center experience from Greece

Pediatric kidney Tx has critically altered the outcome in ESRD pediatric patients. The aims of this study were to determine long-term graft and patient survival in a homogeneous ethnic population. We reviewed the medical charts of pediatric kidney Tx performed between 1990 and 2012 in Greece. Seventy-five kidney Txs were performed from LRD and 62 from DD. The 10- and 20-yr graft survival was higher in LRD Tx compared with DD Tx. Both patient and graft survival at 10 and 20 yr after Tx were similar in LRD Tx from grandparents compared with parents (92.9% vs. 93.4% 20-yr patient survival, 71.4% vs. 78.7% and 57.1% vs. 72.1%, 10- and 20-yr graft survival, respectively). However, there was a decreasing tendency in LRD Tx rates in period 2001-2012 compared with period 1990-2000 (47.1% vs. 62.7%). Risk factors for poor five-yr graft survival were DD Tx, and induction treatment with ALG compared with basiliximab, but their effect attenuated at 10 yr after Tx. In conclusion, Tx from LRD may offer efficient survival outcomes irrespective of donor age, suggesting that even older LRD could be an excellent option for the 1st kidney Tx in children and adolescents.

Identification of subgroups by risk of graft failure after paediatric renal transplantation: application of survival tree models on the ESPN/ERA-EDTA Registry

BACKGROUND

Identification of patient groups by risk of renal graft loss might be helpful for accurate patient counselling and clinical decision-making. Survival tree models are an alternative statistical approach to identify subgroups, offering cut-off points for covariates and an easy-to-interpret representation.

METHODS

Within the European Society of Pediatric Nephrology/European Renal Association-European Dialysis and Transplant Association (ESPN/ERA-EDTA) Registry data we identified paediatric patient groups with specific profiles for 5-year renal graft survival. Two analyses were performed, including (i) parameters known at time of transplantation and (ii) additional clinical measurements obtained early after transplantation. The identified subgroups were added as covariates in two survival models. The prognostic performance of the models was tested and compared with conventional Cox regression analyses.

RESULTS

The first analysis included 5275 paediatric renal transplants. The best 5-year graft survival (90.4%) was found among patients who received a renal graft as a pre-emptive transplantation or after short-term dialysis (<45 days), whereas graft survival was poorest (51.7%) in adolescents transplanted after long-term dialysis (>2.2 years). The Cox model including both pre-transplant factors and tree subgroups had a significantly better predictive performance than conventional Cox regression (P < 0.001). In the analysis including clinical factors, graft survival ranged from 97.3% [younger patients with estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m(2) and dialysis <20 months] to 34.7% (adolescents with eGFR <60 mL/min/1.73 m(2) and dialysis >20 months). Also in this case combining tree findings and clinical factors improved the predictive performance as compared with conventional Cox model models (P < 0.0001).

CONCLUSIONS

In conclusion, we demonstrated the tree model to be an accurate and attractive tool to predict graft failure for patients with specific characteristics. This may aid the evaluation of individual graft prognosis and thereby the design of measures to improve graft survival in the poor prognosis groups.

Choosing the order of deceased donor and living donor kidney transplantation in pediatric recipients: a Markov decision process model

BACKGROUND

Most pediatric kidney transplant recipients eventually require retransplantation, and the most advantageous timing strategy regarding deceased and living donor transplantation in candidates with only 1 living donor remains unclear.

METHODS

A patient-oriented Markov decision process model was designed to compare, for a given patient with 1 living donor, living-donor-first followed if necessary by deceased donor retransplantation versus deceased-donor-first followed if necessary by living donor (if still able to donate) or deceased donor (if not) retransplantation. Based on Scientific Registry of Transplant Recipients data, the model was designed to account for waitlist, graft, and patient survival, sensitization, increased risk of graft failure seen during late adolescence, and differential deceased donor waiting times based on pediatric priority allocation policies. Based on national cohort data, the model was also designed to account for aging or disease development, leading to ineligibility of the living donor over time.

RESULTS

Given a set of candidate and living donor characteristics, the Markov model provides the expected patient survival over a time horizon of 20 years. For the most highly sensitized patients (panel reactive antibody > 80%), a deceased-donor-first strategy was advantageous, but for all other patients (panel reactive antibody < 80%), a living-donor-first strategy was recommended.

CONCLUSIONS

This Markov model illustrates how patients, families, and providers can be provided information and predictions regarding the most advantageous use of deceased donor versus living donor transplantation for pediatric recipients.

Racial and ethnic disparities in pediatric renal allograft survival in the United States

This study was undertaken to describe the association of patient race/ethnicity and renal allograft survival among the national cohort of pediatric renal allograft recipients. Additionally, we determined whether racial and ethnic differences in graft survival exist among individuals living in low or high poverty neighborhoods and those with private or public insurance. Among 6,216 incident, pediatric End Stage Renal Disease patients in the United States Renal Data System (kidney transplant from 2000 through September, 2011) 14.4% experienced graft failure, with a median follow-up time of 4.5 years. After controlling for multiple covariates, black race, but not Hispanic ethnicity, was significantly associated with a higher rate of graft failure for both deceased and living donor transplant recipients. Disparities were particularly stark by 5 years post-transplant, when black living donor transplant recipients experienced only 63.0% graft survival compared with 82.8% and 80.8% for Hispanics and whites, respectively. These disparities persisted among high and low poverty neighborhoods and among both privately- and publicly-insured patients. Notably profound declines in both deceased and living donor graft survival rates for black, compared to white and Hispanic, children preceded the 3-year mark when transplant Medicare eligibility ends. Further research is needed to identify the unique barriers to long-term graft success among black pediatric transplant recipients.

Mortality after pediatric kidney transplantation in England--a population-based cohort study

The aim of this study was to explore mortality after pediatric kidney transplantation in England over the last decade. We used data from HES to select all kidney transplant procedures performed in England between April 2001 and March 2012. Data linkage analysis was performed with the ONS to identify all deaths occurring among this study cohort. Data for 1189 pediatric recipients were compared to 17 914 adult recipients (number of deaths, 33 vs. 2052, respectively, p < 0.001), with median follow-up 4.4 yr (interquartile range 2.2-7.3 yr). There was no difference in mortality within the pediatric cohort; age 0-1 (n = 25, patient survival 100.0%), age 2-5 (n = 198, patient survival 96.0%), age 6-12 (n = 359, patient survival 97.5%), and age 13-18 (n = 607, patient survival 97.4%), respectively (p = 0.567). The most common causes of death were renal (n = 8, 24.2%), infection (n = 6, 18.2%), and malignancy (n = 5, 15.2%). All deaths from malignancy were secondary to PTLD. In a fully adjusted Cox regression model, only white ethnicity was significantly associated with risk of pediatric mortality post-kidney transplantation (hazard ratio 2.7, 95% confidence interval [1.0-7.3], p = 0.047). To conclude, this population-based cohort study confirms low mortality after pediatric kidney transplantation with short follow-up.

Surgical complications and graft survival in pediatric kidney transplant recipients treated with a steroid-free protocol: experiences from a Danish university hospital

BACKGROUND

The outcome of pediatric kidney transplantation depends on several factors, among these are the complications, which occur in relation to the surgical procedure. In this study, we present our experience with pediatric kidney transplantation in a steroid-free immunosuppression regimen, from a surgical point of view.

METHODS

Patient charts of pediatric kidney transplantations in the period 1998-2011 were reviewed. Surgical complications, acute rejection, and patient and graft survivals were recorded.

RESULTS

Sixty-one renal transplantations were performed in 58 patients. Thirty patients (49.1%) experienced a surgical complication, of which 11 (18%) required an explorative laparotomy. Overall the five-year Kaplan-Meier patient survival rate was 96.2% and the graft survival rate was 88.6%. Nine patients (14.7%) had an acute rejection episode within the first year after transplantation. No correlation was observed between surgical complications and acute rejection episodes or graft loss.

CONCLUSIONS

This study indicated a high incidence of surgical complications among pediatric kidney transplantations when using a steroid-free immunosuppression regimen. Despite this, we observed high overall patient and graft survival, supporting the trend toward steroids avoidance in pediatric kidney transplantation.

Order of donor type in pediatric kidney transplant recipients requiring retransplantation

BACKGROUND

Living-donor kidney transplantation (KT) is encouraged for children with end-stage renal disease due to superior long-term graft survival compared with deceased-donor KT. Despite this, there has been a steady decrease in the use of living-donor KT for pediatric recipients. Due to their young age at transplantation, most pediatric recipients eventually require retransplantation, and the optimal order of donor type is not clear.

METHODS

Using the Scientific Registry of Transplant Recipients, we analyzed first and second graft survival among 14,799 pediatric (<18 years old) recipients undergoing KT between 1987 and 2010.

RESULTS

Living-donor grafts had longer survival compared with deceased-donor grafts, similarly among both first (adjusted hazard ratio [aHR], 0.78; 95% confidence interval [CI], 0.73-0.84; P<0.001) and second (aHR, 0.74; 95% CI, 0.64-0.84; P<0.001) transplants. Living-donor second grafts had longer survival compared with deceased-donor second grafts, similarly after living-donor (aHR, 0.68; 95% CI, 0.56-0.83; P<0.001) and deceased-donor (aHR, 0.77; 95% CI, 0.63-0.95; P=0.02) first transplants. Cumulative graft life of two transplants was similar regardless of the order of deceased-donor and living-donor transplantation.

CONCLUSIONS

Deceased-donor KT in pediatric recipients followed by living-donor retransplantation does not negatively impact the living-donor graft survival advantage and provides similar cumulative graft life compared with living-donor KT followed by deceased-donor retransplantation. Clinical decision-making for pediatric patients with healthy, willing living donors should consider these findings in addition to the risk of sensitization, aging of the living donor, and deceased-donor waiting times.

Disparities in policies, practices and rates of pediatric kidney transplantation in Europe

We aimed to provide an overview of kidney allocation policies related to children and pediatric kidney transplantation (KTx) practices and rates in Europe, and to study factors associated with KTx rates. A survey was distributed among renal registry representatives in 38 European countries. Additional data were obtained from the ESPN/ERA-EDTA and ERA-EDTA registries. Thirty-two countries (84%) responded. The median incidence rate of pediatric KTx was 5.7 (range 0-13.5) per million children (pmc). A median proportion of 17% (interquartile range 2-29) of KTx was performed preemptively, while the median proportion of living donor KTx was 43% (interquartile range 10-52). The median percentage of children on renal replacement therapy (RRT) with a functioning graft was 62%. The level of pediatric prioritization was associated with a decreased waiting time for deceased donor KTx, an increased pediatric KTx rate, and a lower proportion of living donor KTx. The rates of pediatric KTx, distribution of donor source and time on waiting list vary considerably between European countries. The lack of harmonization in kidney allocation to children raises medical and ethical issues. Harmonization of pediatric allocation policies should be prioritized.

Living unrelated renal transplantation: a good match for the pediatric candidate?

BACKGROUND/PURPOSE

Living donor kidney transplantation is encouraged for children with end-stage renal disease given the superior survival of living donor grafts, but pediatric candidates are also given preference for kidneys from younger deceased donors.

METHODS

Death-censored graft survival of pediatric kidney-only transplants performed in the U.S. between 1987-2012 was compared across living related (LRRT) (n=7741), living unrelated (LURT) (n=618), and deceased donor renal transplants (DDRT) (n=8945) using Kaplan-Meier analysis, multivariable Cox proportional hazards models, and matched controls analysis.

RESULTS

As expected, HLA mismatch was greater among LURT compared to LRRT (p<0.001). Unadjusted graft survival was lower, particularly long-term, for LURT compared to LRRT (p=0.009). However, LURT graft survival was still superior to DDRT graft survival, even when compared only to deceased donors under age 35 (p=0.002). The difference in graft survival between LURT and LRRT was not seen when adjusting for HLA mismatch, year of transplantation, and donor and recipient characteristics using a Cox model (aHR=1.04, 95% CI: 0.87-1.24, p=0.7) or matched controls (HR=1.02, 95% CI: 0.82-1.27, p=0.9).

CONCLUSION

Survival of LURT grafts is superior to grafts from younger deceased donors and equivalent to LRRT grafts when adjusting for other factors, most notably differences in HLA mismatch.

Policy variation in donor and recipient status in 11 pediatric renal transplantation centers

BACKGROUND

Evidence-based guidelines for pediatric renal transplantation (Tx) are lacking. This may lead to unwanted treatment variations. We aimed to quantify the variation in treatment policies and its consequences in daily practice in 11 centers that provide renal Tx for children in three European countries.

METHODS

We surveyed Tx policies in all ten centers in the Netherlands and Belgium and one center in Germany. We compared Tx policies with the therapies actually provided and with recommendations from available published guidelines and existing literature. Information on treatment policies was obtained by a questionnaire; information on care actually provided was registered prospectively from 2007 to 2011. The clinical guidelines were identified by searches of MEDLINE and websites of pediatric nephrology organizations.

RESULTS

Between centers, we found discrepancies in policies on: the minimum accepted recipient weight (8-12 kg), the maximum living and deceased donor age (50-75 and 45-60 years, respectively). HLA-match policies varied between acceptation of all mismatches to at least 1A1B1DR match donor transplantations amounting to 49 % in the Netherlands versus 26 % in Belgium (p = 0.006).

CONCLUSIONS

Management policies for renal Tx in children vary considerably between centers and nations. This has a direct impact on the delivered care, and by extrapolation, on health outcome.

Inferior allograft outcomes in adolescent recipients of renal transplants from ideal deceased donors

OBJECTIVE

To measure the impact of the Share-35 policy on the allocation of ideal deceased donor kidneys and to examine the impact of age on outcomes after kidney transplantation using ideal donor kidneys.

BACKGROUND

In the United States, through Share-35, transplant candidates aged 18 years or younger receive priority for the highest-quality deceased donor kidneys. Adolescent (15-18 years) kidney transplant recipients (KTRs), however, may be more susceptible to allograft loss due to elevated rates of acute rejection and a possible increased risk of primary renal disease recurrence.

METHODS

We used registry data to perform a retrospective cohort study of 39,136 KTRs from January 1, 1994, to December 31, 2008. Ideal donors were defined as 2 to 34 years old with creatinine <1.5 mg/dL and absence of hypertension, diabetes, and hepatitis C.

RESULTS

After Share-35, the percentage of ideal donor kidneys allocated to pediatric recipients increased from 7% to 16%. In multivariable Cox regression, compared with adolescent KTRs, all age strata except recipients older than 70 years had a lower risk of allograft failure (P < 0.01 for each comparison); results were similar after excluding KTRs with diseases at high risk of recurrence. Adolescent recipients had higher mortality rates than KTRs younger than 14 years, similar mortality compared with that of KTRs older than 18 and younger than 40 years, and lower mortality than KTRs older than 40 years.

CONCLUSIONS

The allocation of "ideal donors" to adolescent recipients may not maximize graft utility. Reevaluation of pediatric allocation priority may offer opportunities to optimize ideal renal allograft survival.

Effect of donor and recipient variables on the long-term live-donor renal allograft survival in children

Objective

We aimed to analyse donor and recipient predictors of graft survival in children who received live-donor renal grafts.

Patients and methods

The study comprised 273 children who received live-donor renal transplants at our center between March 1976 and October 2010. The follow-up ranged from 6 months to 25 years. Donor variables included donor age, gender, donor/recipient body weight ratio (DR BWR), ABO blood groups, human leukocyte antigen, and DR mismatching. Donor-specific problems, e.g., ischemia time during surgery and number of renal arteries, were included. Recipient variables included recipient age, sex, original kidney disease, ischemia time, acute tubular necrosis (ATN) after transplantation, immunosuppression, number of acute rejection episodes, re-transplantation, and development of hypertension.

Results

Independent variables with a sustained effect on the 5- and 10-year graft survival on multivariate analysis were: ATN after transplant, number of acute rejections, hypertension, and DR BWR. At the last follow-up, 185 patients (67.8%) had a functioning graft, while 82 (30.0%) had graft failure. Only six patients (0.02%) were lost to follow-up.

Conclusion

Donor and recipient variables that affect short- and long-term graft survival in children with a live-donor renal allograft are DR BWR, number of acute rejections, ATN and hypertension after transplant. Considering these variables provides a better outcome.

Pediatric renal transplantation: an overview and update

PURPOSE OF REVIEW

Transplantation is the preferred method of treatment for end-stage renal disease in children. The rate of pediatric kidney transplantation has been steadily rising over the past decade. The use of increasingly potent immunosuppressive drugs has lessened the risk for acute rejection substantially and improved short-term outcomes; however, the long-term outcomes have remained inadequate.

RECENT FINDINGS

The follow-up of pediatric cohorts and the encouraging results from data registries prompt us to revisit our practices in transplantation so as to devise additional strategies to improve long-term outcomes.

SUMMARY

This review presents a comprehensive discussion of the major issues in pediatric renal transplantation, the newer immunosuppression approaches to limit toxicities of therapies in children and some critical issues that remain to be addressed, specific to the care of the transplanted child. The ultimate goal of designing optimum conditions for equating graft survival to patient survival still remains a major goal for pediatric organ transplantation.