Pediatric transplantation

Vaccination practices in pediatric transplantation: A survey among member centers of the European reference network TransplantChild

BACKGROUND

There is considerable variation in vaccination practices between pediatric transplant centers. This study aims to evaluate active immunization attitudes and practices among ERN-TransplantChild centers and identify potential areas of improvement that could be addressed by shared evidence-based protocols.

METHODS

A cross-sectional questionnaire of attitudes and practices toward immunization of pediatric SOT and HSCT candidates and recipients was sent to a representative member of multidisciplinary teams from 27 European centers belonging to the ERN-TransplantChild.

RESULTS

A total of 28/62 SOT programs and 6/12 HSCT programs across 21 European centers participated. A quarter of centers did not have an on-site protocol for the immunizations. At the time of transplantation, pediatric candidates were fully immunized (80%-100%) in 57% and 33% of the SOT and HSCT programs. Variations in the time between vaccine administration and admission to the waiting list were reported between the centers, with 2 weeks for inactivated vaccines and variable time (2-4 weeks) for live-attenuated vaccines (LAVs). Almost all sites recommended immunization in the post-transplant period, with a time window of 4-8 months for the inactivated vaccines and 16-24 months for MMR and Varicella vaccines. Only five sites administer LAVs after transplantation, with seroconversion evaluated in 80% of cases.

CONCLUSIONS

The immunization coverage of European pediatric transplant recipients is still inconsistent and far from adequate. This survey is a starting point for developing shared evidence-based immunization protocols for safe vaccination among pediatric transplant centers and generating new research studies.

Serum Proteomics Uncovers Biomarkers of Clinical Portal Hypertension in Children With Biliary Atresia

Children with biliary atresia (BA) often develop portal hypertension (PHT) and its complications, which are associated with high morbidity and mortality. The goal of this study was to identify serum biomarkers of PHT by using large-scale proteomics. We applied the slow off-rate modified aptamer scan (SOMAscan) to measure 1,305 proteins in serum samples of children with BA with and without clinical evidence of PHT in validation and discovery cohorts enrolled in the Biliary Atresia Study of Infants and Children. Serum proteomics data was analyzed using logistic regression to identify protein(s) with an area under the receiver operating characteristic curve (AUROC) ≥ 0.90. Immunostaining was used to characterize the cellular localization of the new biomarker proteins in liver tissues. We identified nine proteins in the discovery cohort (n = 40 subjects) and five proteins in the validation cohort (n = 80 subjects) that individually or in combination predicted clinical PHT with AUROCs ≥ 0.90. Merging the two cohorts, we found that semaphorin 6B (SEMA6B) alone and three other protein combinations (SEMA6B+secreted frizzle protein 3 [SFRP3], SEMA6B+COMM domain containing 7 [COMMD7], and vascular cell adhesion molecule 1 [VCAM1]+BMX nonreceptor tyrosine kinase [BMX]) had AUROCs ≥ 0.90 in both cohorts, with high positive- and negative-predictive values. Immunostaining of the new protein biomarkers showed increased expression in hepatic endothelial cells, cholangiocytes, and immune cells within portal triads in BA livers with clinical PHT compared to healthy livers. Conclusion: Large-scale proteomics identified SEMA6B, SFRP3, COMMD7, BMX, and VCAM1 as biomarkers highly associated with clinical PHT in BA. The expression of the biomarkers in hepatic epithelial, endothelial, and immune cells support their potential role in the pathophysiology of PHT.

Factors associated with long-term graft survival in pediatric kidney transplant recipients

Pediatric kidney transplant recipients generally have good outcomes post-transplantation. However, the younger age and longer life span after transplantation in the pediatric population make understanding the multifactorial nature of long-term graft survival critical. This investigation analyzes factors associated with 10-year survival to identify areas for improvement in patient care. Kaplan-Meier with log-rank test and univariable and multivariable logistic regression methods were used to retrospectively analyze 7785 kidney transplant recipients under the age of 18 years from January 1, 1998, until March 9, 2008, using United Network for Organ Sharing (UNOS) data. Our end-point was death-censored 10-year graft survival after excluding recipients whose grafts failed within one year of transplant. Recipients aged 5-18 years had lower 10-year graft survival, which worsened as age increased: 5-9 years (OR: 0.66; CI: 0.52-0.83), 10-14 years (OR: 0.43; CI: 0.33-0.55), and 15-18 years (OR: 0.34; CI: 0.26-0.44). Recipient African American ethnicity (OR: 0.67; CI: 0.58-0.78) and Hispanic donor ethnicity (OR: 0.82; CI: 0.72-0.94) had worse outcomes than other donor and recipient ethnicities, as did patients on dialysis at the time of transplant (OR: 0.82; CI: 0.73-0.91). Recipient private insurance status (OR: 1.35; CI: 1.22-1.50) was protective for 10-year graft survival. By establishing the role of age, race, and insurance status on long-term graft survival, we hope to guide clinicians in identifying patients at high risk for graft failure. This study highlights the need for increased allocation of resources and medical care to reduce the disparity in outcomes for certain patient populations.

The role of extracorporeal membrane oxygenation in pediatric abdominal transplant patients: A qualitative systematic review of literature

BACKGROUND

Advances in ECMO have made it a useful adjunct in critically ill pediatric patients; however, a dearth of evidence exists regarding risks and benefits in pediatric abdominal transplantation. The purpose of this study was to perform a qualitative systematic review of outcomes in pediatric patients undergoing ECMO support pre- or post-abdominal organ transplantation.

METHODS

This was a systematic review conducted from Jan 1, 1989, to April 24, 2020, via PubMed, Embase, Scopus, Web of Science, the Cochrane Library, and ClinicalTrials.gov of all pediatric solid abdominal organ transplant recipients (pre- and post-transplant) and donors who underwent V-A or V-V ECMO cannulation. Death was the primary outcome, with graft function and complications as secondary outcomes.

RESULTS

Fourteen articles were identified that fit criteria, with 88% being case reports. Three patients were donors placed on ECMO, with no mortality among the 8 recipients of organs from these donors. Nineteen recipients were placed on ECMO. All were liver transplants. Most patients experienced at least one complication (84%), with bleeding as the most common cause (44%). Mortality was 26%. Causes of death included multiorgan system failure (n = 3), heart failure (n = 1), Systemic inflammatory response syndrome (n = 1), abdominal compartment syndrome (n = 3), bleeding (n = 1), septic shock from aspergillus (n = 1), and hepatic artery thrombosis (n = 2).

CONCLUSIONS

The data are poor on ECMO usage in pediatric abdominal transplantation. While complications were high, mortality did not appear to be related to ECMO usage and was relatively low given the severity of patient illness.

Pediatric living donor liver transplantation with large-for-size left lateral segment grafts

Usage of "large-for-size" left lateral segment (LLS) liver grafts in children with high graft to recipient weight ratio (GRWR) is controversial due to concerns about increased recipient complications. During the study period, 77 pediatric living donor liver transplantations (LDLTs) with LLS grafts were performed. We compared recipients with GRWR ≥2.5% (GR-High = 50) vs GRWR <2.5% (GR-Low = 27). Median age was higher in the GR-Low group (40 vs 8 months, P> .0001). Graft (GR-High: 98%, 98%, 98% vs GR-Low: 96%, 93%, 93%) and patient (GR-High: 98%, 98%, 98% vs GR-Low: 100%, 96%, 96%) survival at 1, 3, and 5 years was similar between groups (P = NS). Overall complications were also similar (34% vs 30%; P = .8). Hepatic artery and portal vein thrombosis following transplantation was not different (P = NS). Delayed abdominal fascia closure was more common in GR-High patients (17 vs 1; P = .002). Subgroup analysis comparing recipients with GRWR ≥4% (GR-XL = 20) to GRWR <2.5% (GRWR-Low = 27) revealed that delayed abdominal fascia closure was more common in the GR-XL group, but postoperative complications and graft and patient survival were similar. We conclude that pediatric LDLT with large-for-size LLS grafts is associated with excellent clinical outcomes. There is an increased need for delayed abdominal closure with no compromise of long-term outcomes. The use of high GRWR expands the donor pool and improves timely access to the benefits of transplantation without extra risks.

Ferumoxytol Is Not Retained in Kidney Allografts in Patients Undergoing Acute Rejection

PURPOSE

To evaluate whether ultrasmall superparamagnetic iron oxide nanoparticle (USPIO)-enhanced magnetic resonance imaging (MRI) can detect allograft rejection in pediatric kidney transplant patients.

PROCEDURES

The USPIO ferumoxytol has a long blood half-life and is phagocytosed by macrophages. In an IRB-approved single-center prospective clinical trial, 26 pediatric patients and adolescents (age 10-26 years) with acute allograft rejection (n = 5), non-rejecting allografts (n = 13), and normal native kidneys (n = 8) underwent multi-echo T2* fast spoiled gradient-echo (FSPGR) MRI after intravenous injection (p.i.) of 5 mg Fe/kg ferumoxytol. T2* relaxation times at 4 h p.i. (perfusion phase) and more than 20 h p.i. (macrophage phase) were compared with biopsy results. The presence of rejection was assessed using the Banff criteria, and the prevalence of macrophages on CD163 immunostains was determined based on a semi-quantitative scoring system. MRI and histology data were compared among patient groups using t tests, analysis of variance, and regression analyses with a significance threshold of p < 0.05.

RESULTS

At 4 h p.i., mean T2* values were 6.6 ± 1.5 ms for native kidneys and 3.9 ms for one allograft undergoing acute immune rejection. Surprisingly, at 20-24 h p.i., one rejecting allograft showed significantly prolonged T2* relaxation times (37.0 ms) compared to native kidneys (6.3 ± 1.7 ms) and non-rejecting allografts (7.6 ± 0.1 ms). Likewise, three additional rejecting allografts showed significantly prolonged T2* relaxation times compared to non-rejecting allografts at later post-contrast time points, 25-97 h p.i. (p = 0.008). Histological analysis revealed edema and compressed microvessels in biopsies of rejecting allografts. Allografts with and without rejection showed insignificant differences in macrophage content on histopathology (p = 0.44).

CONCLUSION

After ferumoxytol administration, renal allografts undergoing acute rejection show prolonged T2* values compared to non-rejecting allografts. Since histology revealed no significant differences in macrophage content, the increasing T2* value is likely due to the combined effect of reduced perfusion and increased edema in rejecting allografts.

Adherence in pediatric kidney transplant recipients: solutions for the system

Non-adherence remains a significant problem among pediatric (and adult) renal transplant recipients. Non-adherence among solid organ transplant recipients results in US$15-100 million annual costs. Estimates of non-adherence range from 30 to 70% among pediatric patients. Research demonstrates that a 10% decrement in adherence is associated with 8% higher hazard of graft failure and mortality. Focus has begun to shift from patient factors that impact adherence to the contributing healthcare and systems factors. The purpose of this review is to describe problems within the systems implicated in non-adherence and potential solutions that may be related to positive adherence outcomes. Systems issues include insurance and legal regulations, provider and care team barriers to optimal care, and difficulties with transitioning to adult care. Potential solutions include recognition of how systems can work together to improve patient outcomes through improvements in insurance programs, a multi-disciplinary care team approach, evidence-based medical management, pharmacy-based applications and interventions to simplify medication regimens, improved transition protocols, and telehealth/technology-based multi-component interventions. However, there remains a significant lack of reliability in the application of these potential solutions to systems issues that impact patient adherence. Future efforts should accordingly focus on these efforts, likely by leveraging quality improvement and related principles, and on the investigation of the efficacy of these interventions to improve adherence and graft outcomes.

Heart transplantation from donation after circulatory determined death

Fifty years since the first successful human heart transplant from a non-heart beating donor, this concept of heart transplantation from donation after circulatory determined death (DCD) promises to be one of the most exciting developments in heart transplantation. Heart transplantation has established itself as the best therapeutic option for patients with end-stage heart failure, with the opportunity to provide these patients with a near-normal quality of life. However, this treatment is severely limited by the availability of suitable donor hearts. In recent times, heart transplantation has been limited to using donor hearts from donors following brain stem death. The use of donor hearts from DCD had been thought to be associated with high risk and poor outcomes until recent developments in organ perfusion and retrieval techniques have shown that this valuable resource may provide an answer to the global shortage of suitable donor hearts. With established DCD heart transplant programmes reporting encouraging results, this technique has been shown to be comparable to the current gold standard of donation after brain death (DBD) heart transplantation.

Special Considerations in Pediatric Kidney Transplantation

Universally accepted as the treatment of choice for children needing renal replacement therapy, kidney transplantation affords children the opportunity for an improved quality of life over dialysis therapy. Immunologic and surgical advances over the last 15 years have improved the pediatric patient and kidney graft survival. Unique to pediatrics, congenital genitourinary anomalies are the most common primary diseases leading to kidney failure, many with urological issues. Early urological evaluation for post-transplant bladder dysfunction and emphasis on immunization adherence are the mainstays of pediatric pretransplant and post-transplant evaluations. A child's height can be challenging, sometimes requiring an intra-abdominally placed graft, particularly if the patient is <20 kg. Maintenance immunosuppression regimens are similar to adult kidney graft recipients, although distinctive pharmacokinetics may change dosing intervals in children from twice a day to thrice a day. Viral infections and secondary malignancies are problematic for children relative to adults. Current trends to reduce/remove corticosteroid therapy from post-transplant protocols have produced improved linear growth with less steroid toxicity; although these studies are still ongoing, graft function and survival are considered acceptable. Finally, all children with a kidney transplant need a smooth transition to adult clinics. Future research in pertinent psychosocial aspects and continued technological advances will only serve to optimize the transition process. Although some aspects of kidney transplantation are similar in children and adults, for instance immunosuppression and immunosuppressive regimens, and rejection mechanisms and their diagnosis using the Banff criteria, there are important differences this review will focus on and which continue to drive innovation.

Outcomes of pediatric living donor kidney transplantation: A single-center experience

Renal transplantation is the treatment of choice for children with ESRD offering advantages of improved survival, growth potential, cognitive development, and quality of life. The aim of our study was to compare the outcomes of LDKT vs DDKT performed in children at a single center. Retrospective chart review of pediatric patients who underwent kidney transplantation from 2005 to 2014 was performed. Ninety-one renal transplants were accomplished, and 31 cases (38.27%) were LDKT, and in 96.7% of the cases, the graft was obtained through laparoscopy. Thirty-four receptors weighted <25 kg. LDKT group had statistically significant lower cold ischemia times than DDKT one. Complication rate was 9.67% for LDKT and 18.33% for DDKT. eGFR was better in LDKT. Patient survival rate was 100% for LDKT and 98.3% for DDKT, and graft survival rate was 96.7% for LDKT and 88.33%-80% for DDKT at a year and 5 years. Our program of pediatric kidney transplantation has achieved optimal patient and graft survival rates with low rate of complications. Living donor pediatric kidney transplants have higher patient and better graft survival rates than deceased donor kidney transplants.

Cutaneous Malignancies in Pediatric Solid Organ Transplant Recipients

Pediatric organ transplant recipients (POTRs) are at risk of developing malignancies due to a combination of immunosuppression, impaired DNA damage repair, and infection with oncogenic viruses. The most commonly developed malignancies in this population are skin cancers, which include nonmelanoma skin cancer, melanoma, Kaposi's sarcoma, and anogenital carcinoma. The literature shows that skin cancers account for 13% to 55% of all cancers that occur after transplantation. Given the increasing number and life expectancy of POTRs, prevention and management of skin cancer in these patients is essential, but there is a substantial knowledge gap in our understanding of the differences in skin cancer development, prevention, and management between POTRs and adult organ transplant recipients (AOTRs), for whom more data are available. Substantial differences have been observed in the patterns of malignancy development between POTRs and AOTRs, and data specific to pediatric populations are needed. The objective of this review is to provide updated information on posttransplantation skin cancer development in POTRs, including epidemiologic research on transplant patients and disease development, medication management, surveillance, and education efforts.

The evolving potential for pediatric ex vivo lung perfusion

Despite the rise in the number of adult lung transplantations performed, rates of pediatric lung transplantation remain low. Lung transplantation is an accepted therapy for pediatric end-stage lung disease; however, it is limited by a shortage of donor organs. EVLP has emerged as a platform for assessment and preservation of donor lung function. EVLP has been adopted in adult lung transplantation and has successfully led to increased adult lung transplantations and donor lung utilization. We discuss the future implications of EVLP utilization, specifically, its potential evolving role in overcoming donor shortages in smaller children and adolescents to improve the quality and outcomes of lung transplantation in pediatric patients.

Repeat Kidney Transplantation After Failed First Transplant in Childhood: Past Performance Informs Future Performance

BACKGROUND AND OBJECTIVES

Kidney transplant graft survival is almost uniformly superior for initial transplants compared to repeat transplants. We investigate the association between first second kidney transplant graft survival in patients who underwent initial transplant during their pediatric years whether age at second transplant is associated with outcome.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

This is a retrospective analysis of Organ Procurement and Transplantation Network data from October 1987 to May 2009 examining second kidney graft survival in 2281 patients who received their first transplant at younger than 18 years using Kaplan-Meier statistics. Factors associated with second graft survival were identified using a multivariable Cox proportional hazards model.

RESULTS

Patients with first kidney graft survival of less than 5 years had better second graft survival compared to patients with first graft survival of 30 days to 5 years (P < 0.01). Patients with first kidney graft survival less than 30 days had similar second kidney graft outcomes(P = 0.50) as those with longer than 5 years first kidney graft survival, demonstrating that very early first graft loss is not associated with poor second transplant outcome. Patients 15 to 20 years of age at second transplant have lower second graft survival compared to other age groups; P less than 0.01, regardless of other recipient/donor characteristics and recurrent disease.

CONCLUSIONS

Poor second transplant outcomes are identified among patients with previous pediatric kidney transplant with first graft survival longer than 30 days, but shorter than 5 years, and those receiving second transplants at a high-risk age category (15-20 years). These groups may benefit from increased attention both before and after transplantation.

High-risk age window for mortality in children with cystic fibrosis after lung transplantation

LTx in children with CF remains controversial. The UNOS database was queried from 1987 to 2013 for CF patients <18 yr of age at time of transplant. PCHR model was used to quantify hazard of mortality. 489 recipients were included in the survival analysis. The hazard function of post-transplant mortality was plotted over attained age to identify age window of highest risk, which was 16-20 yr. Unadjusted PCHR model revealed ages immediately after the high-risk window were characterized by lower hazard of mortality (HR = 0.472; 95% CI = 0.302, 0.738; p = 0.001). After adjusting for potential confounders, the decline in mortality hazard immediately after the high-risk window remained statistically significant (HR = 0.394; 95% CI: 0.211, 0.737; p = 0.004). Hazard of mortality in children with CF after LTx was highest between 16 and 20 yr of attained age and declined thereafter.

Loss of pediatric kidney grafts during the "high-risk age window": insights from pediatric liver and simultaneous liver-kidney recipients

Pediatric kidney transplant recipients experience a high-risk age window of increased graft loss during late adolescence and early adulthood that has been attributed primarily to sociobehavioral mechanisms such as nonadherence. An examination of how this age window affects recipients of other organs may inform the extent to which sociobehavioral mechanisms are to blame or whether kidney-specific biologic mechanisms may also exist. Graft loss risk across current recipient age was compared between pediatric kidney (n = 17,446), liver (n = 12,161) and simultaneous liver-kidney (n = 224) transplants using piecewise-constant hazard rate models. Kidney graft loss during late adolescence and early adulthood (ages 17-24 years) was significantly greater than during ages <17 (aHR = 1.79, 95%CI = 1.69-1.90, p < 0.001) and ages >24 (aHR = 1.11, 95%CI = 1.03-1.20, p = 0.005). In contrast, liver graft loss during ages 17-24 was no different than during ages <17 (aHR = 1.03, 95%CI = 0.92-1.16, p = 0.6) or ages >24 (aHR = 1.18, 95%CI = 0.98-1.42, p = 0.1). In simultaneous liver-kidney recipients, a trend towards increased kidney compared to liver graft loss was observed during ages 17-24 years. Late adolescence and early adulthood are less detrimental to pediatric liver grafts compared to kidney grafts, suggesting that sociobehavioral mechanisms alone may be insufficient to create the high-risk age window and that additional biologic mechanisms may also be required.

Selection of living donor liver grafts for patients weighing 6kg or less

In the field of pediatric living donor liver transplantation (LDLT), physicians sometimes must reduce the volume of left lateral segment (LLS) grafts to prevent large-for-size syndrome. There are 2 established methods for decreasing the size of an LLS graft: the use of a segment 2 (S2) monosegment graft and the use of a reduced LLS graft. However, no procedure for selecting the proper graft type has been established. In this study, we conducted a retrospective investigation of LDLT and examined the strategy of graft selection for patients weighing ≤6 kg. LDLT was conducted 225 times between May 2001 and December 2012, and 15 of the procedures were performed in patients weighing ≤6 kg. We selected S2 monosegment grafts and reduced LLS grafts if the preoperative computed tomography (CT)-volumetry value of the LLS graft was >5% and 4% to 5% of the graft/recipient weight ratio, respectively. We used LLS grafts in 7 recipients, S2 monosegment grafts in 4 recipients, reduced S2 monosegment grafts in 3 recipients, and a reduced LLS graft in 1 recipient. The reduction rate of S2 monosegment grafts for use as LLS grafts was 48.3%. The overall recipient and graft survival rates were both 93.3%, and 1 patient died of a brain hemorrhage. Major surgical complications included hepatic artery thrombosis in 2 recipients, bilioenteric anastomotic strictures in 2 recipients, and portal vein thrombosis in 1 recipient. In conclusion, our graft selection strategy based on preoperative CT-volumetry is highly useful in patients weighing ≤6 kg. S2 monosegment grafts are effective and safe in very small infants particularly neonates.

Medication adherence in the transition of adolescent kidney transplant recipients to the adult care

Non-adherence is common in adolescent and young adult kidney transplant recipients, leading to adverse graft outcomes. The aim of this study was to determine whether adherence to immunosuppressant medications changes during transition from a pediatric to an adult program within the same transplant center. Adherence was assessed for a period of two yr before and two yr after the transfer. Subtherapeutic trough levels of serum tacrolimus and level variability were used as measures of adherence. Twenty-five patients were transitioned between 1996 and 2011 at the median age of 22.3 [IQR 21.6-23.0] yr. Young adults 21-25 yr of age (n = 26) and non-transitioned adolescents 17-21 yr of age (currently followed in the program, n = 24 and those that lost their grafts prior to the transfer, 22) formed the comparison groups. In the transitioned group, adherence prior to the transfer was not significantly different from the adherence after the transfer (p = 0.53). The rate of non-adherence in the group of non-transitioned adolescents who lost their grafts (68%) was significantly higher than in the transitioned group (32%, p = 0.01). In the group of young adults, adherence was not significantly different from the transitioned group (p = 0.27). Thus, transition was not associated with differences in medication adherence in this single-center study. Large-scale studies are needed to evaluate the national data on medication adherence after transfer.

National trends over 25 years in pediatric kidney transplant outcomes

OBJECTIVE

To investigate changes in pediatric kidney transplant outcomes over time and potential variations in these changes between the early and late posttransplant periods and across subgroups based on recipient, donor, and transplant characteristics.

METHODS

Using multiple logistic regression and multivariable Cox models, graft and patient outcomes were analyzed in 17,446 pediatric kidney-only transplants performed in the United States between 1987 and 2012.

RESULTS

Ten-year patient and graft survival rates were 90.5% and 60.2%, respectively, after transplantation in 2001, compared with 77.6% and 46.8% after transplantation in 1987. Primary nonfunction and delayed graft function occurred in 3.3% and 5.3%, respectively, of transplants performed in 2011, compared with 15.4% and 19.7% of those performed in 1987. Adjusted for recipient, donor, and transplant characteristics, these improvements corresponded to a 5% decreased hazard of graft loss, 5% decreased hazard of death, 10% decreased odds of primary nonfunction, and 5% decreased odds of delayed graft function with each more recent year of transplantation. Graft survival improvements were lower in adolescent and female recipients, those receiving pretransplant dialysis, and those with focal segmental glomerulosclerosis. Patient survival improvements were higher in those with elevated peak panel reactive antibody. Both patient and graft survival improvements were most pronounced in the first posttransplant year.

CONCLUSIONS

Outcomes after pediatric kidney transplantation have improved dramatically over time for all recipient subgroups, especially for highly sensitized recipients. Most improvement in graft and patient survival has come in the first year after transplantation, highlighting the need for continued progress in long-term outcomes.

Deceased-donor split-liver transplantation in adult recipients: is the learning curve over?

BACKGROUND

Infants have the highest wait-list mortality of all liver transplantation candidates. Deceased-donor split-liver transplantation, a technique that provides both an adult and pediatric graft, might be the best way to decrease this disproportionate mortality. Yet concern for an increased risk to adult split recipients has discouraged its widespread adoption. We aimed to determine the current risk of graft failure in adult recipients after split-liver transplantation.

STUDY DESIGN

United Network for Organ Sharing data from 62,190 first-time adult recipients of deceased-donor liver transplants (1995-2010) were analyzed (889 split grafts). Bivariate risk factors (p < 0.2) were included in Cox proportional hazards models of the effect of transplant type on graft failure.

RESULTS

Split-liver recipients had an overall hazard ratio of graft failure of 1.26 (p < 0.001) compared with whole-liver recipients. The split-liver hazard ratio was 1.45 (p < 0.001) in the pre-Model for End-Stage Liver Disease era (1995-2002) and 1.10 (p = 0.28) in the Model for End-Stage Liver Disease era (2002-2010). Interaction analyses suggested an increased risk of split-graft failure in status 1 recipients and those given an exception for hepatocellular carcinoma. Excluding higher-risk recipients, split and whole grafts had similar outcomes (hazard ratio = 0.94; p = 0.59).

CONCLUSIONS

The risk of graft failure is now similar between split and whole-liver recipients in the vast majority of cases, which demonstrates that the expansion of split-liver allocation might be possible without increasing the overall risk of long-term graft failure in adult recipients. Additional prospective analysis should examine if selection bias might account for the possible increase in risk for recipients with hepatocellular carcinoma or designated status 1.

Deceased donor liver transplantation in infants and small children: are partial grafts riskier than whole organs?

Infants have the highest wait-list mortality of all liver transplant candidates. Although previous studies have demonstrated that young children may be at increased risk when they receive partial grafts from adult and adolescent deceased donors (DDs), with few size-matched organs available, these grafts have increasingly been used to expand the pediatric donor pool. We aimed to determine the current adjusted risks of graft failure and mortality in young pediatric recipients of partial DD livers and to determine whether these risks have changed over time. We analyzed 2683 first-time recipients of DD livers alone under the age of 24 months in the United Network for Organ Sharing database (1995-2010), which included 1118 partial DD livers and 1565 whole DD organs. Transplant factors associated with graft loss in bivariate analyses (P < 0.1) were included in multivariate proportional hazards models of graft and patient survival. Interaction analysis was used to examine risks over time (1995-2000, 2001-2005, and 2006-2010). Although there were significant differences in crude graft survival by the graft type in 1995-2000 (P < 0.001), graft survival rates with partial and whole grafts were comparable in 2001-2005 (P = 0.43) and 2006-2010 (P = 0.36). Furthermore, although the adjusted hazards for partial graft failure and mortality were 1.40 [95% confidence interval (CI) = 1.05-1.89] and 1.41 (95% CI = 0.95-2.09), respectively, in 1995-2000, the adjusted risks of graft failure and mortality were comparable for partial and whole organs in 2006-2010 [hazard ratio (HR) for graft failure = 0.81, 95% CI = 0.56-1.18; HR for mortality = 1.02, 95% CI = 0.66-1.71]. In conclusion, partial DD liver transplantation has become less risky over time and now has outcomes comparable to those of whole liver transplantation for infants and young children. This study supports the use of partial DD liver grafts in young children in an attempt to significantly increase the pediatric organ pool.

Current issues in pediatric liver transplantation

Pediatric patients with ESLD requiring liver transplantation often have a multitude of comorbidities ranging from pulmonary hypertension to renal and cardiovascular insufficiency that impairs our ability to safely care for these critically ill children. As organ allocation techniques advance, many of these patients may be healthier on arrival to the operating room. However, postoperative surgical complications and immunosuppressive regimens still daunt us. As we continue to care for these challenging patients, hopefully, advances in ESLD management and technology will dramatically improve outcomes in the future.

Age at graft loss after pediatric kidney transplantation: exploring the high-risk age window

BACKGROUND AND OBJECTIVE

The risk of graft loss after pediatric kidney transplantation increases during late adolescence and early adulthood, but the extent to which this phenomenon affects all recipients is unknown. This study explored interactions between recipient factors and this high-risk age window, searching for a recipient phenotype that may be less susceptible during this detrimental age interval.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

With use of Scientific Registry of Transplant Recipients data from 1987 to 2010, risk of graft loss across recipient age was quantified using a multivariable piecewise-constant hazard rate model with time-varying coefficients for recipient risk factors.

RESULTS

Among 16,266 recipients, graft loss during ages ≥17 and <24 years was greater than that for both 3-17 years (adjusted hazard ratio [aHR], 1.61; P<0.001) and ≥24 years (aHR, 1.28; P<0.001). This finding was consistent across age at transplantation, sex, race, cause of renal disease, insurance type, pretransplant dialysis history, previous transplant, peak panel-reactive antibody (PRA), and type of induction immunosuppression. The high-risk window was seen in both living-donor and deceased-donor transplant recipients, at all levels of HLA mismatch, regardless of centers' pediatric transplant volume, and consistently over time. The relationship between graft loss risk and donor type, PRA, transplant history, insurance type, and cause of renal disease was diminished upon entry into the high-risk window.

CONCLUSIONS

No recipient subgroups are exempt from the dramatic increase in graft loss during late adolescence and early adulthood, a high-risk window that modifies the relationship between typical recipient risk factors and graft loss.

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.

Trends in wait-list mortality in children listed for heart transplantation in the United States: era effect across racial/ethnic groups

We sought to evaluate trends in overall and race-specific pediatric heart transplant (HT) wait-list mortality in the United States (US) during the last 20 years. We identified all children <18 years old listed for primary HT in the US during 1989-2009 (N = 8096, 62% White, 19% Black, 13% Hispanic and 6% Other) using the Organ Procurement and Transplant Network database. Wait-list mortality was assessed in four successive eras (1989-1994, 1995-1999, 2000-2004 and 2005-2009). Overall wait-list mortality declined in successive eras (26%, 23%, 18% and 13%, respectively). The decline across eras remained significant in adjusted analysis (hazard ratio [HR] 0.70 in successive eras, 95% confidence interval [CI], 0.67-0.74) and was 67% lower for children listed during 2005-2009 versus those listed during 1989-1994 (HR 0.33; CI, 0.28-0.39). In models stratified by race, wait-list mortality decreased in all racial groups in successive eras. In models stratified by era, minority children were not at higher risk of wait-list mortality in the most recent era. We conclude that the risk of wait-list mortality among US children listed for HT has decreased by two-thirds during the last 20 years. Racial gaps in wait-list mortality present variably in the past are not present in the current era.

Graft failure and adaptation period to adult healthcare centers in pediatric renal transplant patients

BACKGROUND

Transfer from pediatric to adult care may require a period of adaptation to the new healthcare environment. We sought to determine whether this adaptation period was associated with an increased risk of graft failure.

METHODS

Children (age, 0-18 years) recorded in the Canadian Organ Replacement Register who received a first kidney transplant in a pediatric health center between 1992 and 2007, and who had more than or equal to 3 months of graft function, were followed up until death, loss to follow-up, or December 31, 2007. Cox proportional hazards models were used to estimate the excess risk associated with a period of adaptation to adult-oriented care, defined as the interval 0.5 years before to 2.5 years after the first recorded adult care visit. Models were adjusted for age, gender, donor source, and ethnicity.

RESULTS

Of the 413 patients evaluated, 149 were transferred to adult care during study period. In total, 78 (18.9%) patients experienced graft failure-23 during the adaptation period. Compared with the period before adaptation, the adjusted hazard ratio for graft loss within the adaptation period was 2.24 (95% confidence interval [CI]: 1.19-4.20). The adjusted graft failure rate was 2.26 (1.04-4.93) times higher after 18 years of age than between 0 and 13 years. Aboriginal ethnicity and deceased donor source were also associated with a significantly higher risk of graft failure.

CONCLUSIONS

The period of adaptation to adult-oriented care is associated with a high risk of graft failure in pediatric renal transplant patients.

Second cadaveric kidney transplantations in the pediatric population

OBJECTIVE

To evaluate the functional outcomes and complications among a series of second in comparison to first kidney transplantations in pediatric patients.

MATERIALS AND METHODS

We reviewed 163 consecutive kidney transplants in pediatric recipients performed from 1978 to present: 120 cases (69.3%) were first transplants (group A) and 43 (24.8%), second transplant (group B). We analyzed the incidences of delayed graft function (DGF), medical and surgical complications, as well as medium- and long-term graft survivals.

RESULTS

We observed DGF among 51 group A patients (43%) versus 32.5% of group B. Ten patients suffered vascular complications in group A (8.3%) versus one in group B (2.3%) (P < .05). The 15-year graft survivals were 54.2% for group A and 45% for group B. The 15-year patient survivals were 84.9% in group A versus 93.6% in group B.

CONCLUSIONS

Second kidney transplantations for children are a satisfactory option that achieves good functional results as well as acceptable graft and patient survivals.

Pharmacogenetics in immunosuppressants: impact on dose requirement of calcineurin inhibitors in renal and liver pediatric transplant recipients

PURPOSE OF REVIEW

Calcineurin inhibitors (CNI) are the mainstay immunosuppressive therapy in pediatric solid organ transplantation. These drugs have narrow therapeutic window, and continuous therapeutic drug monitoring is required to keep blood levels within the therapeutic range. Personalization of immunosuppressive therapy according to the genetic profile may provide a way to optimize drug dosing from the first day of transplantation. In this review, we will highlight the recent pharmacogenetic studies of CNIs in pediatric renal and liver transplantation.

RECENT FINDINGS

CNIs are metabolized by CYP3A4 and CYP3A5. In the intestine, the absorption of these drugs is limited by the P-glycoprotein efflux transporter. Most of the pediatric studies showed an association between CYP3A5 genetic variation and CNI dosing. Carriers of the wild-type allele (CYP3A5*1) required higher doses of CNIs as compared with individuals homozygous to the variant CYP3A5*3 allele. CYP3A4 and ABCB1 (encoding P-glycoprotein) genetic variations did not show an association with CNI dosing.

SUMMARY

The pharmacogenetics of CNIs has been widely investigated in adults, little is known about this field in the pediatric groups. Prospective studies are needed to elucidate the effect of genetic variations on CNI drug dosing and to investigate their impact on short and long-term clinical outcome.

Characteristics of long-term immunosuppressive therapy in Chinese pediatric renal transplant patients: a single-center experience

We performed this study to investigate the trend and characteristics of various immunosuppressive regimens as well as their efficacy and safety for long-term survival of Chinese pediatric renal allograft recipients.

METHODS

Thirty-four patients who underwent kidney transplantation between January 1985 and July 2002 had >/=5 years follow up. We retrospectively reviewed the baseline characteristics, patient and kidney survival rates, renal function, immunosuppressive regimens, drug levels, and adverse effects of immunosuppressive medications.

RESULTS

The 1-, 3-, and 5-year recipient versus graft survival rates were 100% and 97.1%; 91.2% and 88.2%; 85.3% and 82.4%, respectively. The proportions of patients treated with cyclosporine- or tacrolimus-based immunosuppressive regimen at these times were 48.5%/51.5%; 60.0%/40.0%; and 53.6/46.4%. There were no significant differences in the dosages and drug levels after 1 year (P > .05). The proportions of azathioprine versus mycophenolate mofetil adjunctive therapy were 21.3/78.8%; 23.3%/70%; and 32.1%/60.7%, respectively. Forty percent of the surviving recipients developed complications, including hypertension, hyperlipidemia, gingival hyperplasia, hirsutism, liver dysfunction, herpes zoster, diabetes mellitus or cataracts.

CONCLUSIONS

Cyclosporine or tacrolimus, plus mycophenolate mofetil or azathioprine, and prednisone triple therapies showed promising long-term results with similar efficacy and safety in pediatric renal recipients. Periodic drug level monitoring is required to facilitate individualization of immunosuppressive regimens. Drug doses and levels differed markedly from non-Chinese patients because of the ethnic discrepancy.

[Concept to improve adherence in adolescents following renal transplantation: vision or reality?]

Transition to adult care is a generic issue for subspecialties dealing with chronic illness and has received little attention to date. The transition from pediatric to adult care for renal transplant recipients is recognized as a high-risk period for poor graft outcome associated with more than 20% graft loss. Non-adherence to immunosuppressive medications is one of the most important factors contributing to graft loss during this period. Transition is, therefore, a concern of both pediatric and adult providers, and medical improvements in this area will require more effective collaboration at this interface. This report explores medical and psychological risk factors and barriers during the transition process. In addition, a specially developed coaching concept for young adults is presented intended to assist adolescents with early childhood end-stage renal disease in the transition from pediatric to adult care.

Kidney transplantation and donation in children

It has been shown that kidney transplantation results in superior life expectancy and quality of life compared with dialysis treatment for patients with end-stage renal disease. However, kidney transplantation in children differs in many aspects from adult kidney transplantation. This review focuses on specific issues of surgical care associated with kidney transplantation in children, including timing of transplantation, technical considerations, patient and graft survival, growth retardation and post-transplant malignancy. At the same time, there is a large discrepancy between the number of available donor kidneys and the number of patients on the waiting list for kidney transplantation. There is a general reluctance to use paediatric donor kidneys, because of relatively frequent complications such as graft thrombosis and early graft failure. We review the specific aspects of kidney transplantation from paediatric donors such as the incidence of graft thrombosis, hyperfiltration injury and 'en bloc' transplantation of two kidneys from one donor with an excellent long-term outcome, which is comparable with adult donor kidney transplantation. We also discuss the potential use of paediatric non-heart-beating donor kidneys, from donors whose heart stopped beating with the preservation techniques used.

Preventable death: children on the transplant waiting list

Children, especially those under 5 years of age, have the highest death rate on the transplant waiting list compared to any other age range. This article discusses the concept, supported by OPTN data, that there is an age range of small pediatric donors, which are almost exclusively transplanted into small pediatric transplant candidates. Allocation policies that allow broader sharing of small pediatric donors into small pediatric candidates are likely to decrease death rates of children on the waiting list. As well, although the number of pediatric deceased donors continues to decline, improving consent rates for eligible pediatric donors, and judicious use of pediatric donors after cardiac death, can enhance the pediatric deceased donor supply.

Pediatric heart transplantation after declaration of cardiocirculatory death

In three infants awaiting orthotopic cardiac transplantation, transplantation was successfully performed with the use of organs from donors who had died from cardiocirculatory causes. The three recipients had blood group O and were in the highest-risk waiting-list category. The mean age of donors was 3.7 days, and the mean time to death after withdrawal from life support was 18.3 minutes. The 6-month survival rate was 100% for the 3 transplant recipients and 84% for 17 control infants who received transplants procured through standard organ donation. The mean number of rejection episodes among the three infants during the first 6 months after surgery was 0.3 per patient, as compared with 0.4 per patient among the controls. Echocardiographic measures of ventricular size and function at 6 months were similar among the three infants and the controls (left ventricular shortening fraction, 43.6% and 44.9%, respectively; P=0.73). No late deaths (within 3.5 years) have occurred in the three infants, and they have had functional and immunologic outcomes similar to those of controls. Mortality while awaiting a transplant is an order of magnitude higher in infants than in adults, and donors who died from cardiocirculatory causes offer an opportunity to decrease this waiting-list mortality.

Extracorporeal life support for severe respiratory failure in children with immune compromised conditions

OBJECTIVES

To examine a large cohort of children treated with extracorporeal life support (ECLS) for severe respiratory failure to investigate the hypothesis that patients with an immune compromise condition (ICC) would have reduced survival to hospital discharge compared with patients without this classification.

DESIGN

Retrospective cohort study.

SETTING

Extracorporeal Life Support Organization (ELSO) data registry.

PATIENTS

All nonneonatal pediatric patients receiving ECLS for respiratory failure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

As of February 4, 2004, the ELSO registry contained 2,879 pediatric patients between 1 month and 19 yrs of age who were treated with ECLS for respiratory failure. Overall, 183 patients had at least one International Classification of Diseases (Ninth Revision) or Current Procedural Terminology code associated with an ICC; ICC status was associated with lower hospital survival (31 vs. 57 %; p < .001). Six ICC subgroups were also examined: immune deficiency, leukemia-lymphoma, cancer, opportunistic infection, solid organ transplant, and bone marrow transplant. Each ICC subgroup was also associated with reduced hospital survival, varying from a high of 34.6% (solid organ transplants) to a low of 0% (bone marrow transplant). In a multivariate logistic regression model that controlled for factors reported to be associated with survival and other respiratory interventions (high-frequency ventilation, inhaled nitric oxide, and surfactant), the presence of an ICC remained associated with reduced hospital survival (odds ratio 0.20-0.45; p < .001). In this multivariate model, an unexpected strong association between inhaled nitric oxide therapy and lower ECLS survival was observed (odds ratio 0.49-0.80; p < .001).

CONCLUSIONS

In this cohort of pediatric patients receiving ECLS for respiratory failure, survival to hospital discharge was reduced for each ICC subgroup examined and was approximately one in three for the overall group. Further study of the association of lower survival rates for patients who received inhaled nitric oxide prior to ECLS is needed.

Improving adherence to medications in pediatric liver transplant recipients

We describe results from a clinical program, which aimed at improving adherence to medications in children who had a liver transplant. We followed the medical outcomes of 23 children and adolescents who participated in a clinical adherence-improvement protocol during the years 2001-2002. The protocol included identification of non-adherent patients by examining tacrolimus blood levels and intervention by increasing the frequency of clinic visits for non-adherent patients. In the two-yr preintervention (1999-2000), there was no improvement in any of the outcomes. After the intervention, the number of patients with high alanine aminotransferase levels (100 and above) decreased significantly, from eight before the intervention to four afterwards. Other outcomes, including the number of rejection episodes (three before, none after) and the degree of adherence to tacrolimus, also improved, but the improvement did not reach statistical significance. Although non-adherent patients were called to clinic more often under the protocol, the intervention did not lead to increased outpatient costs. This adherence--improvement intervention appears to be promising in improving outcomes in pediatric liver transplant recipients. Larger, controlled studies are needed to establish the efficacy of this or other approaches.

Pediatric organ donation: what factors most influence parents' donation decisions?

OBJECTIVE

To identify factors that influence parents' decisions when asked to donate a deceased child's organs.

DESIGN

Cross-sectional design with data collection via structured telephone interviews.

SETTING

One organ procurement organization in the Southeastern United States.

PARTICIPANTS

Seventy-four parents (49 donors, 25 nondonors) of donor-eligible deceased children who were previously approached by coordinators from one organ procurement organization in the southeastern United States.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multivariate analyses showed that organ donation was more likely when the parent was a registered organ donor (odds ratio [OR] = 1.4, confidence interval [CI] = 1.1, 2.7), the parent had favorable organ donation beliefs (OR = 5.5, CI = 2.7, 12.3), the parent was exposed to organ donation information before the child's death (OR = 2.6, CI = 1.7, 10.3), a member of the child's healthcare team first mentioned organ donation (OR = 1.4, CI = 1.2, 3.7), the requestor was perceived as sensitive to the family's needs (OR = 0.4, CI = 0.2, 0.7), the family had sufficient time to discuss donation (OR = 5.2, CI = 1.4, 11.6), and family members were in agreement about donation (OR = 2.8, CI = 1.3, 5.2).

CONCLUSIONS

This study identifies several modifiable variables that influence the donation decision-making process for parents. Strategies to facilitate targeted organ donation education and higher consent rates are discussed.

A national conference to determine research priorities in pediatric solid organ transplantation

The need for evidence-based practice guidelines requires high quality, carefully controlled clinical research trials. This multidisciplinary conference attempted to: identify urgent clinical and research issues, identify obstacles to performing clinical trials, develop concepts for organ-specific and all-organ research and generate a report that would serve as a blueprint for future research initiatives. A few themes became evident. First, young children present a unique immunologic environment which may lead to tolerance, therefore, including young children in immunosuppression withdrawal and tolerance trials may increase the potential benefits of these studies. Second, adolescence poses significant barriers to successful transplantation. Non-adherence may be insufficient to explain poorer outcomes. More studies focused on identification and prevention of non-adherence, and the potential effects of puberty are required. Third, the relatively naive immune system of the child presents a unique opportunity to study primary infections and alloimmune responses. Finally, relatively small numbers of transplants performed in pediatric centers mandate multicenter collaboration. Investment in registries, tissue and DNA repositories will enhance productivity. The past decade has proven that outcomes after pediatric transplantation can be comparable to adults. The pediatric community now has the opportunity to design and complete studies that enhance outcomes for all transplant recipients.

The long-term outcomes of pediatric kidney transplantation: a single-centre experience in China

To explore the long-term outcomes of paediatric kidney transplantation and the effects of renal allograft on growth, education, employment, marriage and procreation. Twenty-seven children with ESRD received the renal allograft from 1985 to 2001. The patient and kidney survival rate, renal function, growth and employment, etc., were reviewed retrospectively. The average follow-up period was 10.3 +/- 4.4 yr. The one-, three-, five- and 10-yr graft survival rates were 96.3%, 88.9%, 81.5% and 66.7%, respectively, and the corresponding patient survival rates were 100%, 92.6%, 85.2% and 68.8%. The body weight gain was 4-10 kg in one-yr post-operative and the height increased 0-2 cm for girls and 2-5 cm for boys. A total of 44.4% of the recipients accomplished their education above junior high school. The employment rate was 46.2% in males, and 57.2% in females. Twelve patients were married. Non-adherence occurred in 30% of the recipients. Forty percent of the surviving recipients developed complications. Seven patients died. More attention should be paid to non-adherence of medications and more supports from the society are required to improve the life quality of paediatric recipients, especially in employment and education.

Acquired Nonneoplastic Neonatal and Pediatric Diseases

The lung biopsy is an established procedure to procure a pathologic diagnosis in a child with a suspected pneumonic process of undetermined etiology. Improvements in pediatric anesthesia and surgery have reduced the operative complications to a minimum. A biopsy can usually be taken through a small intercostal incision when localization is not especially important in a patient with diffuse changes (see Chapter 1). The alternative method for tissue sampling is the endoscopic transbronchial biopsy. There is less risk to the patient, but the specimen is smaller and crush artifacts from the instrument are more common.

Identification of medication non-adherence factors in adolescent transplant patients: the patient's viewpoint

Studies report a clear association between medication non-adherence and an unfavorable transplant outcome. The adolescent population, in particular, has difficulty adhering to post-transplant medication regimens. The purpose of this study is to identify, categorize and understand the opinions of adolescent transplant patients regarding why they may not take their medications as prescribed. From January to August 2005, nine adolescent kidney transplant patients at an urban medical center were surveyed and asked to rank-order 33 statements regarding their opinions on why adolescents may not take their medications as prescribed. Q-methodology, a powerful tool in subjective study, was used to identify and categorize the viewpoints of adolescents on this subject. Three factors emerged and were labeled to reflect their distinct viewpoints: (1) Medication Issues (e.g. taste, size, frequency, schedule), (2) Troubled Adolescent (e.g. poor home life, depression, overwhelming situation), and (3) Deliberate Non-Adherer (e.g. attention-seeker, infallible attitude). By understanding these different viewpoints and the factors that contribute to them, it may be easier to identify which management approach to non-adherence works best in specific subgroups of patients.