Pediatric transplantation

Pediatric transplantation in the United States, 1996-2005

Solid organ transplantation is accepted as a standard lifesaving therapy for end-stage organ failure in children. This article reviews trends in pediatric transplantation from 1996 to 2005 using OPTN data analyzed by the Scientific Registry of Transplant Recipients. Over this period, children have contributed significantly to the donor pool, and although the number of pediatric donors has fallen from 1062 to 900, this still accounts for 12% of all deceased donors. In 2005, 2% of 89,884 candidates listed for transplantation were less than 18 years old; in 2005, 1955 children, or 7% of 28,105 recipients, received a transplant. Improvement in waiting list mortality is documented for most organs, but pretransplant mortality, especially among the youngest children, remains a concern. Posttransplant survival for both patients and allografts similarly has shown improvement throughout the period; in most cases, survival is as good as or better than that seen in adults. Examination of immunosuppressive practices shows an increasing tendency across organs toward tacrolimus-based regimens. In addition, use of induction immunotherapy in the form of anti-lymphocyte antibody preparations, especially the interleukin-2 receptor antagonists, has increased steadily. Despite documented advances in care and outcomes for children undergoing transplantation, several considerations remain that require attention as we attempt to optimize transplant management.

Immunosuppression in pediatric solid organ transplantation: opportunities, risks, and management

The pediatric transplant community stands at a time of unprecedented choice of immunosuppressive agents - and with a legacy of morbidity from those agents used in the previous two decades. This review considers the clinical utility and side-effect profiles of immunosuppressants used widely in current practice (e.g., glucocorticoids, azathioprine, ciclosporin, tacrolimus, mycophenolate, and sirolimus) and those agents which are in increasing use or in evaluation (e.g., IL-2 receptor antibodies, everolimus, FTY720, LEA29Y, and deoxyspergualin). Further consideration is given to the wider drug interactions likely during the use of new immunosuppressant regimens and to our growing awareness of the influences of genetic heterogeneity on drug efficacy and handling. Finally, we consider the new demands being placed on the use of drug monitoring to regulate dosage of this new repertoire of immunosuppressants.

Safety, tolerability, and efficacy of everolimus in de novo liver transplant recipients: 12- and 36-month results

Everolimus is a macrolide immunosuppressive agent with known consistent absorption. In this double-blind study, we examined the safety and tolerability of everolimus vs. placebo in de novo liver transplant recipients. One hundred and nineteen liver allograft recipients were randomized to 1 of 4 groups: everolimus 0.5 mg bid, everolimus 1.0 mg bid, everolimus 2 mg bid, or placebo. Patients received oral cyclosporine to achieve a target trough level of 150-400 ng/mL in combination with prednisone. Primary and secondary endpoints of safety, tolerability, and efficacy were determined at 12 months, and patients were followed through 36 months. There was a trend toward fewer treated acute rejections in the everolimus group than in the placebo group: everolimus 0.5 mg: 39.3%; everolimus 1.0 mg: 30.0%; everolimus 2 mg: 29.0%; placebo: 40.0% (P = not significant). Adverse events were higher in everolimus-treated patients especially at the 4-mg/day dose, but there was no difference in the incidence of thrombocytopenia or leukopenia between all groups and renal function as determined by serum creatinine, and creatinine clearance remained stable to 36 months in everolimus-treated patients. Mean cholesterol and triglycerides increased from baseline in all treatment groups, and maximum levels were seen at 6 months. In conclusion, this study demonstrates that everolimus in combination with oral cyclosporine had an acceptable safety and tolerability profile, paving the way for additional studies in this transplant indication.

Vascular reconstruction and complications in living donor liver transplantation in infants weighing less than 6 kilograms: the Kyoto experience

Smaller-size infants undergoing living-donor liver transplantation (LDLT) are at increased risks of vascular complications because of their smaller vascular structures in addition to vascular pedicles of insufficient length for reconstruction. Out of 585 child patients transplanted between June 1990 and March 2005, 64 (10%) weighing less than 6 kg underwent 65 LDLTs. Median age and weight were 6.9 months (range: 1-16 months) and 5 kg (range: 2.8-5.9 kg), respectively. Forty-five lateral segment, 12 monosegment, and 8 reduced monosegment grafts were adopted, and median graft-to-recipient weight ratio was 4.4% (range: 2.3-9.7). Outflow obstruction occurred in only 1 patient (1.5%). Portal vein complication occurred in 9 (14%) including 5 with portal vein thrombosis. Hepatic artery thrombosis (HAT) occurred in 5 (7.7%). Patient and graft survivals were 73% and 72% at 1 yr, and 69% and 68% at 5 yr after LDLT, respectively. Thirteen of 22 grafts (58%) lost during the follow-up period occurred within the first 3 months posttransplantation. Overall graft survival in patients with and without portal vein complication was 67% and 65%, respectively (P = 0.54). Overall graft survival in patients with and without HAT was 40% and 67%, respectively. HAT significantly affected graft survival (P = 0.04). In conclusion, our surgical technique for smaller-size recipients resulted in an acceptable rate of vascular complications. Overcoming early posttransplantation complications will further improve outcomes in infantile LDLT.

Immunosuppression in pediatric solid organ transplantation

This report reviews the immunosuppressive regimens that are used in pediatric transplantation. There are predominant themes developing in the field involving the minimization of the total exposure of immunosuppression through limiting the number of agents and newer pharmacokinetic modeling. Calcineurin inhibitors are the foundation of most immunosuppressive regimens. However, there are new pharmacologic monitoring techniques to reduce the potential for long-term side effects of this class of agents. Although tacrolimus remains one of the mainstays of current protocols, there are strides being made to reduce the patient's long-term exposure to it with transitioning to sirolimus. Corticosteroids are still used predominantly, but there is growing evidence of successful steroid-sparing protocols that are as effective and avoid the chronic morbidity of steroids. Antibody induction therapy remains a standard with clearer evidence of the efficacy of IL-2 receptor antagonists. There is preliminary clinical evidence that polyclonal antibody therapy is efficacious in pediatric transplantation. Future studies will determine the best way to assess the functional immune status of a pediatric transplant recipient to maintain the fine balance and avoid the complications of either excessive or inadequate immunosuppression.

Outcomes after liver transplantation: keep the end in mind

Since the advent of transplantation as a life-saving procedure for patients with end-stage liver disease, more than 15,000 children and adolescents have received liver transplants. With the improvements in long-term posttransplant survival offered by advances in medical and surgical therapy, the concept of transplantation outcome has expanded beyond simple patient and graft survival rates. The quality of the life years restored, the long-term complications of transplant immunosuppression, and the overall cost of care have been increasingly recognized as important components of liver transplantation outcome. This review focuses on the efforts of a single pediatric transplant center to examine the incidence of, and risk factors for, common posttransplantation complications, to characterize posttransplantation health-related quality of life, to describe the cost of posttransplant care, and to implement novel programs to improve health care delivery. Together, these projects set the future course for research and care improvement initiatives in this population and encourage us to "keep the end in mind" when considering pediatric liver transplantation.

Pediatric transplantation in the United States, 1995-2004

This article reviews trends in pediatric solid organ transplantation over the last decade, as reflected in OPTN/SRTR data. In 2004, children younger than 18 years made up nearly 3% of the 86,378 candidates for organ transplantation and nearly 7% of the 27,031 organ transplant recipients. Children accounted for nearly 14% of the 7152 deceased organ donors. The transplant community recognizes important differences between pediatric and adult organ transplant recipients, including different etiologies of organ failure, surgical procedures that are more complex or technically challenging, effects of development on the pharmacokinetic properties of common immunosuppressants, unique immunological aspects of transplant in the developing immune system and increased susceptibility to posttransplant complications, particularly infectious diseases. For these reasons, and because of the impact of end-stage organ failure on growth and development, the transplant community has generally provided pediatric candidates with special consideration in the allocation of deceased donor organs. Outcomes following kidney, liver and heart transplantation in children often rank among the best. This article emphasizes that the prospects for solid organ transplantation in children, especially those aged 1-10 years are excellent. It also identifies themes warranting further consideration, including organ availability, adolescent survival and challenges facing pediatric transplant clinical research.

Trends over a decade of pediatric liver transplantation in the United States

During the last 10 to 15 years, medical and surgical innovations have established pediatric liver transplantation as the optimal therapy for children suffering acute and chronic liver disease. We hypothesized that the profile of current pediatric liver transplant recipients would differ significantly from that of an earlier era. We collected and compared data regarding the characteristics of children undergoing liver transplantation alone in 2 eras separated by more than a decade from the Organ Procurement and Transplantation Network/United Network for Organ Sharing database. Transplant recipients from March 1, 2002 to December 31, 2004, compared to those from January 1, 1990, to December 31, 1992, tended to be more evenly distributed across age, race/ethnicity, and disease etiology. There was a major shift toward utilization of partial grafts from both deceased and living donors to achieve transplantation for the youngest children (<1 and 1-5 yr) in particular. However, in spite of these innovative transplant strategies and only a modest increase in demand for pediatric liver transplantation, wait list times for both pediatric candidates and recipients have still increased between eras. In conclusion, the sobering reality that mortality on the waiting list remains highest for the youngest pediatric liver candidates frames our challenge for the next decade.

NICU update: state of the science of NEC

Necrotizing enterocolitis (NEC) is a disease process that is frequently seen in the neonatal intensive care unit (NICU) and in preterm newborns. The pathophysiology of NEC is a detailed multifactorial theory that will not be thoroughly discussed in this article. The key risk factors leading to NEC are prematurity, formula feeding, intestinal ischemia, and bacterial colonization. Current research regarding feeding practices, surgical techniques, bowel transplantation, and use of probiotics is presented to update NICU nurses on the state of the science of care for the newborn with NEC. Caring for the sick neonate involves holistic family care. Listening to and supporting parents through the stressful stay in the NICU can empower them to be better prepared and educated to take their newborns home.

An in vitro Shwartzman reaction-like response is augmented age-dependently in human peripheral blood mononuclear cells

A lethal human septic shock model, mouse generalized Shwartzman reaction (GSR), was elicited by two consecutive lippolysaccharide (LPS) injections (24 h apart) in which interferon-gamma (IFN-gamma) induced by interleukin (IL)-12 played a critical role in the priming phase, and tumor necrosis factor (TNF) was an important effector molecule in the second phase. We recently reported IL-12/LPS-induced mouse GSR age-dependently enhanced. We herein demonstrate that human peripheral blood mononuclear cells (PBMC) from healthy adults/elderly, cultured with IL-12 for 24 h and with LPS for an additional 24 h, produced a much larger amount of TNF (which increased age-dependently) than did PBMC without IL-12 priming. Whereas macrophages mainly produced TNF following LPS stimulation, macrophages and lymphocytes were necessary for a sufficient TNF production. IL-12-induced IFN-gamma up-regulated Toll-like receptor 4 (TLR-4) on macrophages of adults. Although the PBMC from children produced a substantial amount of IFN-gamma after IL-12 priming, the GSR response, with augmented TNF production and an up-regulated TLR-4 expression of macrophages, was not elicited by LPS stimulation. CD56+natural killer cells, CD56+T cells, and CD57+T cells (NK-T cells), which age-dependently increased in PBMC, produced much larger amounts of IFN-gamma after IL-12 priming than that of conventional CD56-CD57-T cells and also induced cocultured macrophages to produce TNF by subsequent LPS stimulation. The elder septic patients were consistently more susceptible to lethal shock with enhanced serum TNF levels than the adult patients. The NK cells, NK-T cells, and macrophages, which change proportionally or functionally with aging, might be involved in the enhanced GSR response/septic shock observed in elderly patients.

Anesthesia Considerations for Pediatric Thoracic Solid Organ Transplant

This article discusses the indications, perioperative management, postoperative complications, and patient outcome of pediatric heart transplantation and pediatric lung transplantation. Special emphasis is placed on the anesthetic considerations relevant for children who are undergoing or have received a solid thoracic organ transplant.

Patient selection in an era of donor liver shortage: current US policy

In the past, organ allocation in the US was based on anecdotal experience, self-interest and the opinions of single centers, with little support in the way of scientific evidence, mathematical survival modeling or validation. As organ transplantation became more successful, and as disparity between the number of patients on the waiting list and available organs became larger, a more justifiable donor allocation scheme became necessary. The current allocation scheme for donor livers is based on the model for end-stage liver disease/pediatric end-stage liver disease, which was introduced in 2002 by the United Network for Organ Sharing. This new allocation system has improved accuracy for predicting pretransplant mortality. In addition, the number of liver transplantations has risen for almost all etiologic categories, most noticeably for patients with hepatocellular carcinoma. Fewer patients have been registered on the liver transplant waiting list and fewer have been removed from the list because they have died or become too sick for transplantation. So far, this new allocation system has been a success, but it does have its shortcomings, and even with improvements to the system, the use of the donor organ pool still needs to be optimized.

Biliary atresia: clinical profiles, risk factors, and outcomes of 755 patients listed for liver transplantation

OBJECTIVES

To test the hypothesis that risk analysis from the time of listing for liver transplantation (LT) focuses attention on areas where outcomes can be improved.

STUDY DESIGN

Competing outcomes and multivariate models were used to determine significant risk factors for pretransplantation and posttransplantation mortality and graft failure in patients with biliary atresia (BA) listed for LT and enrolled in the Studies of Pediatric Liver Transplantation (SPLIT) registry.

RESULTS

Of 755 patients, most were infants (age < 1 year). Significant waiting list mortality risk factors included infancy and pediatric end-stage liver disease (PELD) score > or = 20, whose components were also continuous risk factors. Survival posttransplantation (n=567) was 88% at 3 years. Most deaths were from infection (37%). Posttransplantation mortality risk factors included infant recipients, height/weight < -2 standard deviations (SD), use of cyclosporine versus tacrolimus and retransplantation. Graft failure risks included height/weight < -2 SD, cadaveric partial donors, donor age < or = 5 months, use of cyclosporine versus tacrolimus, and rejection.

CONCLUSIONS

Referral for LT should be anticipatory for infants with BA with failed portoenterostomies. Failing nutrition should prompt aggressive support. Post-LT risk factors are mainly nonsurgical, including nutrition, the relative risk of infection over rejection, and the choice of immunosuppression.

Workshop on late renal allograft dysfunction

Despite continued improvement in incidence of acute immune injury and short-term graft survival, late allograft dysfunction remains a significant problem in the renal transplant population. Recent reports suggest that rates of renal function decline are quite varied in the overall recipient population, and that individual rates for many recipients may not change substantially over time. Moreover, analyses also reveal distinct predictive factors for both early and late functional decline. Long-term outcome studies for renal transplantation, however, might be significantly limited by incomplete data sets for assessing clinical endpoints. In view of the heterogeneous factors that may cause progressive allograft injury, more routine biopsy sampling would allow a more complete characterization of induced injuries. Elucidating mechanisms of renal fibrosis in response to injury, in experimental systems and humans, is also an important goal in better understanding chronic allograft damage. Regulation of cell senescence genes and epithelial to mesenchymal transition, studied in other models of renal fibrosis, are likely relevant to studies of renal allograft dysfunction. Recent technical advances in analyzing biological samples may play a pivotal role in identifying and validating surrogate markers of allograft function for future interventional trials in transplantation.

Sirolimus for solid organ transplantation in children

Sirolimus represents a major advancement in the field of solid organ transplantation and is being used as a rescue agent for acute and chronic rejection as well as for primary immunosuppression with good graft outcome. Although initial studies with sirolimus were in adults, now significant data have accumulated on the role of sirolimus in pediatric solid organ transplantation. This article reviews the current status of sirolimus in pediatric transplantation.

Medication non-adherence in the adolescent renal transplant recipient: a clinician's viewpoint

Recent advancements in immunosuppression and surgical techniques have significantly improved the outcome of kidney transplantation in the pediatric population. Adolescents enjoy the best 1-year graft survival of any age group. However, the long-term transplant outcome in adolescents is disappointing. Non-adherence with immunosuppressive medications is one of the most important contributing factors for graft rejection and loss in teenagers. The impact of non-adherence is perceived to be far more powerful in adolescent transplant recipients than in the transplant population as a whole. To better understand adolescent non-adherence, the process of transplantation must be placed in the context of adolescent development. Adolescents try to establish their identity and autonomy separately from the parents; however at the same time, adolescents with chronic illness require help, support and guidance from adults, including parents and medical personnel. Adolescents have limited ability to anticipate abstractly the long-term consequences of their immediate actions. This inconsistency can create frustration in both adolescents and in the supporting systems around them. Despite the significant consequences of adolescent non-adherence, research in this area is scarce. There are still no established definitions, standardized diagnostic methods and effective interventions to treat and prevent this problem. We propose the recommendations to approach the problems of adolescent transplant non-adherence from the transplant clinician's viewpoint. With early identification and appropriate interventions, significant improvement in adolescent graft survival is possible.

Growing pains: non-adherence with the immunosuppressive regimen in adolescent transplant recipients

One-year graft and patient survival are better in adolescent transplant recipients (age 11-19 years) than in younger (age < 11 years) pediatric transplant recipients. However, several groups found that long-term outcomes (> i.e. 5 year post-transplant) in the adolescent age group are significantly worse than in younger transplant recipients. A behavioral factor that could explain an important part of the poorer clinical outcome in adolescent transplant recipients is non-compliance with medication taking. Adolescents, like all organ transplant recipients irrespective of their age, must adhere to a life-long immunosuppressive regimen in addition to other aspects of their therapeutic regimen. Therefore, adolescent transplant recipients, as all transplant patients, should be regarded as a chronically ill patient population in whom behavioral and psychosocial management is equally important as state-of-the-art medical management. This paper provides an overview of the current knowledge on prevalence, clinical consequences, and risk-factors for non-compliance with the immunosuppressive regimen in adolescent transplant recipients and offers some suggestions for adolescent-tailored interventions to improve medication adherence.

Pediatric transplantation, 1994-2003

This article uses OPTN/SRTR data to review trends in pediatric transplantation over the last decade. In 2003, children younger than 18 made up 3% of the 82,885 candidates for organ transplantation and 7% of the 25,469 organ transplant recipients. Children accounted for 14% of the 6,455 deceased organ donors. Pediatric organ transplant recipients differ from their adult counterparts in several important aspects, including the underlying etiology of organ failure, the complexity of the surgical procedures, the pharmacokinetic properties of common immunosuppressants, the immune response following transplantation, the number and degree of comorbid conditions, and the susceptibility to post-transplant complications, especially infectious diseases. Specialized pediatric organ transplant programs have been developed to address these special problems. The transplant community has responded to the particular needs of children and has provided them special consideration in the allocation of deceased donor organs. As a result of these programs and protocols, children are now frequently the most successful recipients of organ transplantation; their outcomes following kidney, liver, and heart transplantation rank among the best. This article demonstrates that substantial improvement is needed in several areas: adolescent outcomes, outcomes following intestine transplants, and waiting list mortality among pediatric heart and lung candidates.

Current status of kidney and pancreas transplantation in the United States, 1994-2003

This article reviews the OPTN/SRTR data collected on kidney and pancreas transplantation during 2003 in the context of trends over the past decade. Overall, the transplant community continued to struggle to meet the increasing demand for kidney and pancreas transplantation. The number of new wait-listed kidney registrants under the age of 50 has remained relatively stable since 1994, but the number of new registrants aged 50 to 64 has doubled. However, there was only a 2.3% increase in the total number of kidney transplants performed in 2003. Expanded criteria donor kidneys made up 20% of all recovered kidneys and 16% of all transplants performed, compared with 15% in the prior year. In May 2003, new rules were implemented to promote equity in kidney organ allocation. These changes seem to have improved access for historically disadvantaged groups, though they have reduced the quality of HLA matching. The effects on long-term outcomes have yet to be measured. Although the majority of SPK recipients are white (82%), the percentage of simultaneous kidney-pancreas recipients who are African-American has increased from 9% in 2000 to 16% in 2003. The percentage of Hispanic/Latino recipients increased from 5% to 9% over the same period.

Predictors of length of stay for pediatric liver transplant recipients

The resources that are directed towards the care of liver transplant recipients are substantial. Approximately 100 million dollars are spent on the hospitalization of the 400-500 children in the United States who undergo liver transplantation each year. Using length of stay as a surrogate marker for hospital resource use, we sought to identify factors that impact length of stay and assess the trends of hospitalization after liver transplantation for a representative population of pediatric liver transplant recipients. The study population was comprised of 956 patients who underwent primary liver transplantation between 1995 and 2003 and survived at least 90 days. Data were retrieved from the Studies of Pediatric Liver Transplantation data registry. The primary outcome was the length of initial hospitalization after liver transplantation. Independent variables were age, gender, race, pediatric end-stage liver disease score (PELD), year of transplantation, organ type, primary disease, length of operation, and insurance status. The mean and standard deviation of length of stay after liver transplantation was 24.0 +/- 24.5 days. Multivariate analyses showed that increased hospital stay was associated with infants less than 1 year of age, fulminant liver failure, receiving a technical variant organ from a cadaveric donor, government insurance, and transplant era (before 1999 vs. 1999 or later). Decreasing height z-scores and increasing length of operation were also associated with increased hospital stay. In conclusion, these parameters accounted for only 11% of the total variance, suggesting that post-transplant complications and course account for much of the variability of resource use in the immediate post-transplant period.