Cholangioscopy in Children and Adolescents: Utilization, Outcomes, and Safety.

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is increasingly utilized for management of biliary disorders in children and adolescents. Practice patterns surrounding cholangioscopy in pediatric patients, however, are largely uncharacterized. METHODS: We retrospectively analyzed all ERCPs in which cholangioscopy was performed on patients 18 and under at our tertiary care children's hospital from 2015 to 2020 using our institution's paper and electronic medical record system. Patient demographics, procedure indications, interventions, and associated adverse events were analyzed. RESULTS: Over the study period, 307 ERCPs were performed on 282 patients at our children's hospital. Cholangioscopy was performed in 36 procedures (11.7%) using the SpyGlass cholangioscope (Boston Scientific). Antibiotics to cover biliary organisms were administered to all patients precholangioscopy. Mean patient age was 13.6 years (range 7-18 years). The 2 most common indications for cholangioscopy included electrohydraulic lithotripsy for biliary stone disease and evaluation of biliary stricture (with incidental finding of biliary web in 2 patients and retained suture material in 2 patients). Adverse events were less prevalent in patients who underwent cholangioscopy relative to those who underwent ERCP. 0/36 (0%) developed post-ERCP pancreatitis, one patient had self-limited melena (possible self-limited postsphincterotomy bleeding). Patient care was enhanced by cholangioscopy in 30/36 (83.3%) of these patients. CONCLUSIONS: These data attest to the safety and clinical utility of cholangioscopy in children and adolescents. Cholangioscopy was performed in just over 11% of pediatric patients who underwent ERCP at our academic medical center-rates similar to those reported in adult patients. The radiation-sparing nature of cholangioscopy, coupled with these data supporting its safety, make it particularly appealing for use in children. Further multi-institution evaluation of the utility, safety, and range of indications for cholangioscopy in other practice settings would be of great interest and help guide endoscopic care.

Nationwide Evolution of Pediatric Endoscopic Retrograde Cholangiopancreatography Indications, Utilization, and Readmissions over Time.

OBJECTIVES: To analyze outcome and utilization trends over time of pediatric endoscopic retrograde cholangiopancreatography (ERCP) in an all-capture US population-level study. STUDY DESIGN: Using the National Inpatient Sample (2005-2014) and National Readmission Database (2010-2014), we identified pediatric (age <20 years) hospitalizations during which ERCP was performed and assessed ERCP-associated readmissions. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify hospitalization diagnoses, comorbidities, and patient/hospital characteristics. Multivariate logistic regression analyses were performed to determine significant predictors (P < .05) of 30-day readmission. RESULTS: A total of 11 060 hospitalized pediatric patients underwent ERCP between 2005 and 2014. Most were female (n = 8859; 81%), aged 14-20 years (n = 9342; 84%), and white (n = 4230; 45%). Most (85%) of ERCPs were therapeutic, and leading indications were biliary (n = 5350; 48%) and pancreatitis (n = 3218; 29%). Thirteen pecent of patients were readmitted post-ERCP. Odds for 30-day readmission were highest for patients with a history of liver transplantation, age 0-4 years, male sex, and obesity (P < .001 for each). Patients in both urban teaching and urban hospitals had much lower odds than those in rural hospitals for prolonged length of stay associated with ERCP. CONCLUSIONS: These data represent a comprehensive study of nationwide trends in age-specific volumes and outcomes following ERCP in the pediatric population and provide important insights into trends in pediatric pancreaticobiliary disease management, as well as practice setting, patient characteristics, and patient comorbidities associated with pediatric post-ERCP outcomes, including readmission and length of stay.

Fluoroscopy Time During Endoscopic Retrograde Cholangiopancreatography Performed for Children and Adolescents is Significantly Higher With Low-volume Endoscopists.

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is a fluoroscopy and endoscopy-based procedure important for diagnosis and management of pediatric pancreaticobiliary disorders. Patient, procedure, endoscopist, and facility characteristics have been shown to influence ERCP complexity and procedure outcomes as well as fluoroscopy utilization in adults; however, the extent to which this is true in pediatric patients remains under-studied and there are minimal data regarding fluoroscopy utilization in pediatric ERCP. METHODS: We retrospectively analyzed ERCPs performed on patients <18 years of age at our tertiary care children's hospital from 2002 to 2017 using our institution's paper and electronic medical record system along with a prospectively maintained radiation exposure database. Procedure complexity was graded using the Stanford Fluoroscopy Complexity Score and the American Society of Gastrointestinal Endoscopy Complexity scale. High-volume endoscopists (HVE) were defined as having a cumulative annual ERCP volume >100 and low-volume endoscopists (LVE) as <100 (pediatric + adult) ERCPs/year. RESULTS: Three hundred eighty-five ERCPs performed on 321 patients were included in this analysis. The mean patient age was 13.4 years (+/- 4.2 years), 77% were index ERCPs (native ampullas), and 81% were performed with therapeutic intent (87% for biliary indication and 13% for pancreatic indication). Fluoroscopy times (FTs) varied between procedures and providers. Median FT was 4.85 (+/- 2.68) minutes. Endoscopist annual ERCP volume was the strongest predictor of FT (P < 0.001). In addition to endoscopist volume, procedure-specific predictors of increased FT included pancreatic indication for the procedure, biliary or pancreatic duct stricture, patient age <4 years or >16 years at the time of ERCP (P < 0.01 for each), and native ampulla. ERCP complexity rating based on the Stanford Fluoroscopy Complexity Score correlated with FT. CONCLUSIONS: Radiation exposure is higher than desirable for pediatric ERCP and varies with endoscopist as well as patient and procedure-specific factors. HVE perform ERCP with lower FT relative to LVE even though HVE procedure complexity was higher. The Stanford Fluoroscopy Score predicted FT for pediatric ERCP, but the ASGE ERCP complexity scale did not. Adaptation and refinement of pediatric-specific ERCP complexity scales including factors, such as patient size and age and indications/interventions more consistent with those encountered in pediatrics could be beneficial.

Successful liver transplantation in mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a fatal disorder characterized by progressive gastrointestinal dysmotility, peripheral neuropathy, leukoencephalopathy, skeletal myopathy, ophthalmoparesis, and ptosis. MNGIE stems from deficient thymidine phosphorylase activity (TP) leading to toxic elevations of plasma thymidine. Hematopoietic stem cell transplant (HSCT) restores TP activity and halts disease progression but has high transplant-related morbidity and mortality. Liver transplant (LT) was reported to restore TP activity in two adult MNGIE patients. We report successful LT in four additional MNGIE patients, including a pediatric patient. Our patients were diagnosed between ages 14 months and 36 years with elevated thymidine levels and biallelic pathogenic variants in TYMP. Two patients presented with progressive gastrointestinal dysmotility, and three demonstrated progressive peripheral neuropathy with two suffering limitations in ambulation. Two patients, including the child, had liver dysfunction and cirrhosis. Following LT, thymidine levels nearly normalized in all four patients and remained low for the duration of follow-up. Disease symptoms stabilized in all patients, with some manifesting improvements, including intestinal function. No patient died, and LT appeared to have a more favorable safety profile than HSCT, especially when liver disease is present. Follow-up studies will need to document the long-term impact of this new approach on disease outcome. Take Home Message: Liver transplantation is effective in stabilizing symptoms and nearly normalizing thymidine levels in patients with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) and may have an improved safety profile over hematopoietic stem cell transplant.

Open-label prospective therapeutic clinical trials: oral vancomycin in children and adults with primary sclerosing cholangitis.

BACKGROUND: Oral vancomycin (OV) in primary sclerosing cholangitis (PSC) has been evaluated as a potential therapeutic agent. We report the long-term biochemical course and outcomes of patients with PSC treated with OV. METHODS: Patients were enrolled in 2 open-label clinical trials (ClinicalTrials.gov Identifier: NCT01802073 and NCT01322386) and offered OV at 50 mg/kg/day in 3 divided doses if weight <30kg, and 500 mg 3 times/day if weight ≥30kg. Patients with biliary strictures requiring stenting or awaiting liver transplant were excluded. Liver biochemistry, MRCP and histology were documented at baseline and while on OV. The primary outcome was a decrease in elevated gamma glutamyl transferase (GGT), alkaline phosphatase (ALP), and/or alanine aminotransferase (ALT) from baseline. RESULTS: 30 subjects were enrolled, and 29 additional subjects who learned of the clinical trial requested OV (total n = 59; median age was 13.5 years [range, 1.5-44 years]; 64.4% were male; and 94.9% had inflammatory bowel disease [IBD]). The median treatment duration was 2.7 years (range, 0.2-14 years). Ninety-six percent (57/59), 81.3% (48/59), and 94.9% (56/59) experienced reduction of GGT, ALP, and ALT, respectively. Furthermore, 39% (23/59), 22% (13/59), and 55.9% (33/59) experienced normalization of GGT, ALP, and ALT, respectively, within the first 6 months of OV treatment. One patient underwent liver transplantation 8 years after beginning OV treatment, and one developed biliary strictures requiring endoscopic intervention. OV was well-tolerated by patients, and no patient developed treatment-related adverse events. CONCLUSION: In PSC, OV was well-tolerated and was associated with improvement in liver chemistry. A randomized placebo-controlled clinical trial is warranted.

Long-term safety and efficacy of glycerol phenylbutyrate for the management of urea cycle disorder patients.

INTRODUCTION: Glycerol phenylbutyrate (GPB) is currently approved for use in the US and Europe for patients of all ages with urea cycle disorders (UCD) who cannot be managed with protein restriction and/or amino acid supplementation alone. Currently available data on GPB is limited to 12 months exposure. Here, we present long-term experience with GPB. METHODS: This was an open-label, long-term safety study of GPB conducted in the US (17 sites) and Canada (1 site) monitoring the use of GPB in UCD patients who had previously completed 12 months of treatment in the previous safety extension studies. Ninety patients completed the previous studies with 88 of these continuing into the long-term evaluation. The duration of therapy was open ended until GPB was commercially available. The primary endpoint was the rate of adverse events (AEs). Secondary endpoints were venous ammonia levels, number and causes of hyperammonemic crises (HACs) and neuropsychological testing. RESULTS: A total of 45 pediatric patients between the ages of 1 to 17 years (median 7 years) and 43 adult patients between the ages of 19 and 61 years (median 30 years) were enrolled. The treatment emergent adverse events (TEAE) reported in ≥10% of adult or pediatric patients were consistent with the TEAEs reported in the previous safety extension studies with no increase in the overall incidence of TEAEs and no new TEAEs that indicated a new safety signal. Mean ammonia levels remained stable and below the adult upper limit of normal (<35 µmol/L) through 24 months of treatment in both the pediatric and adult population. Over time, glutamine levels decreased in the overall population. The mean annualized rate of HACs (0.29) established in the previously reported 12-month follow-up study was maintained with continued GPB exposure. CONCLUSION: Following the completion of 12-month follow-up studies with GPB treatment, UCD patients were followed for an additional median of 1.85 (range 0 to 5.86) years in the present study with continued maintenance of ammonia control, similar rates of adverse events, and no new adverse events identified.

Pediatric Endoscopy Practice Patterns in the United States, Canada, and Mexico.

BACKGROUND AND AIMS: Endoscopic procedures are important for diagnosis and management of many gastrointestinal, liver, and biliary conditions in children. Therapeutic endoscopy procedures, including endoscopic retrograde cholangiopancreatography (ERCP), are performed less frequently in children relative to adults. A formal study to evaluate institutional volumes and practice patterns for advanced therapeutic pediatric endoscopy procedures has, however, not been previously undertaken. METHODS: A self-administered 16-question (5-minute) online survey assessing practice patterns for performance of pediatric endoscopy procedures was distributed to all registered North American Society for Pediatric Gastroenterology, Hepatology and Nutrition programs. Results were analyzed using descriptive statistics and thematic analysis of free-text comments. RESULTS: Respondents from 82.9% of North American Society for Pediatric Gastroenterology, Hepatology and Nutrition centers completed this survey. Responses revealed that esophagogastroduodenoscopy/colonoscopy are performed at the vast majority of centers (>90%), with most performing >50/year. Therapeutic endoscopy procedures are performed less frequently in the pediatric population, with 18.97% reporting that ERCP is not performed at their institution. Where ERCP is performed, 91.38% reported <25/year. Endoscopic ultrasound is not performed at more than half (53.33%) of institutions. Approximately 71.67% of respondents do not believe their institution's current arrangement for performing pediatric therapeutic endoscopy procedures is adequate. CONCLUSIONS: Although the range of endoscopic procedures performed in children parallels that performed in adults, there are notable differences in pediatric and adult gastroenterologists' endoscopy training and procedure volumes. Our results and respondent comments suggest that pediatric patients would benefit from a partnership between pediatric and adult gastroenterologists, with adult gastroenterologists performing more complex therapeutic endoscopic procedures.

Prenatal treatment of ornithine transcarbamylase deficiency.

PURPOSE OF STUDY: Patients with neonatal urea cycle defects (UCDs) typically experience severe hyperammonemia during the first days of life, which results in serious neurological injury or death. Long-term prognosis despite optimal pharmacological and dietary therapy is still poor. The combination of intravenous sodium phenylacetate and sodium benzoate (Ammonul®) can eliminate nitrogen waste independent of the urea cycle. We report attempts to improve outcomes for males with severe ornithine transcarbamylase deficiency (OTCD), a severe X-linked condition, via prenatal intravenous administration of Ammonul and arginine to heterozygous carrier females of OTCD during labor. METHODS USED: Two heterozygote OTCD mothers carrying male fetuses with a prenatal diagnosis of OTCD received intravenous Ammonul, arginine and dextrose-containing fluids shortly before birth. Maintenance Ammonul and arginine infusions and high-caloric enteral nutrition were started immediately after birth. Ammonul metabolites were measured in umbilical cord blood and the blood of the newborn immediately after delivery. Serial ammonia and biochemical analyses were performed following delivery. SUMMARY OF RESULTS: Therapeutic concentrations of Ammonul metabolites were detected in umbilical cord and neonatal blood samples. Plasma ammonia and glutamine levels in the postnatal period were within the normal range. Peak ammonia levels in the first 24-48h were 53mcmol/l and 62mcmol/l respectively. The boys did not experience neurological sequelae secondary to hyperammonemia and received liver transplantation at ages 3months and 5months. The patients show normal development at ages 7 and 3years. CONCLUSION: Prenatal treatment of mothers who harbor severe OTCD mutations and carry affected male fetuses with intravenous Ammonul and arginine, followed by immediate institution of maintenance infusions after delivery, results in therapeutic levels of benzoate and phenylacetate in the newborn at delivery and, in conjunction with high-caloric enteral nutrition, prevents acute hyperammonemia and neurological decompensation. Following initial medical management, early liver transplantation may improve developmental outcome.

Mass cytometry reveals a distinct immunoprofile of operational tolerance in pediatric liver transplantation.

Long-term IS in transplant patients has significant morbidity, poorer quality of life, and substantial economic costs. TOL, defined as graft acceptance without functional impairment in the absence of IS, has been achieved in some pediatric LT recipients. Using mass cytometry, peripheral blood immunotyping was performed to characterize differences between tolerant patients and patients who are stable on single-agent IS. Single-cell mass cytometry was performed using blood samples from a single-center pediatric LT population of operationally tolerant patients to comprehensively characterize the immune cell populations in the tolerant state compared with patients on chronic low-dose IS. Specific T-cell populations of interest were confirmed by flow cytometry. This high-dimensional phenotypic analysis revealed distinct immunoprofiles between transplant populations as well as a CD4+ TOT (CD4+ CD5+ CD25+ CD38-/lo CD45RA) that correlates with tolerance in pediatric LT recipients. In TOL patients, the TOT was significantly increased as compared to patients stable on low levels of IS. This TOT cell was confirmed by flow cytometry and is distinct from classic Treg cells. These results demonstrate the power of mass cytometry to discover significant immune cell signatures that have diagnostic potential.

Blood ammonia and glutamine as predictors of hyperammonemic crises in patients with urea cycle disorder.

PURPOSE: The aim of this study was to examine predictors of ammonia exposure and hyperammonemic crises in patients with urea cycle disorders. METHODS: The relationships between fasting ammonia, daily ammonia exposure, and hyperammonemic crises were analyzed in >100 patients with urea cycle disorders. RESULTS: Fasting ammonia correlated strongly with daily ammonia exposure (r = 0.764; P < 0.001). For patients with fasting ammonia concentrations <0.5 upper limit of normal (ULN), 0.5 to <1.0 ULN, and ≥1.0 ULN, the probability of a normal average daily ammonia value was 87, 60, and 39%, respectively, and 10.3, 14.1, and 37.0% of these patients, respectively, experienced ≥1 hyperammonemic crisis over 12 months. Time to first hyperammonemic crisis was shorter (P = 0.008) and relative risk (4.5×; P = 0.011) and rate (~5×, P = 0.006) of hyperammonemic crises were higher in patients with fasting ammonia ≥1.0 ULN vs. <0.5ULN; relative risk was even greater (20×; P = 0.009) in patients ≥6 years old. A 10- or 25-µmol/l increase in ammonia exposure increased the relative risk of a hyperammonemic crisis by 50 and >200% (P < 0.0001), respectively. The relationship between ammonia and hyperammonemic crisis risk seemed to be independent of treatment, age, urea cycle disorder subtype, dietary protein intake, or blood urea nitrogen. Fasting glutamine correlated weakly with daily ammonia exposure assessed as 24-hour area under the curve and was not a significant predictor of hyperammonemic crisis. CONCLUSION: Fasting ammonia correlates strongly and positively with daily ammonia exposure and with the risk and rate of hyperammonemic crises, suggesting that patients with urea cycle disorder may benefit from tight ammonia control.

Self-reported treatment-associated symptoms among patients with urea cycle disorders participating in glycerol phenylbutyrate clinical trials.

BACKGROUND: Health care outcomes have been increasingly assessed through health-related quality of life (HRQoL) measures. While the introduction of nitrogen-scavenging medications has improved survival in patients with urea cycle disorders (UCDs), they are often associated with side effects that may affect patient compliance and outcomes. METHODS: Symptoms commonly associated with nitrogen-scavenging medications were evaluated in 100 adult and pediatric participants using a non-validated UCD-specific questionnaire. Patients or their caregivers responded to a pre-defined list of symptoms known to be associated with the use of these medications. Responses were collected at baseline (while patients were receiving sodium phenylbutyrate [NaPBA]) and during treatment with glycerol phenylbutyrate (GPB). RESULTS: After 3 months of GPB dosing, there were significant reductions in the proportion of patients with treatment-associated symptoms (69% vs. 46%; p<0.0001), the number of symptoms per patient (2.5 vs. 1.1; p<0.0001), and frequency of the more commonly reported individual symptoms such as body odor, abdominal pain, nausea, burning sensation in mouth, vomiting, and heartburn (p<0.05). The reduction in symptoms was observed in both pediatric and adult patients. The presence or absence of symptoms or change in severity did not correlate with plasma ammonia levels or NaPBA dose. CONCLUSIONS: The reduction in symptoms following 3 months of open-label GPB dosing was similar in pediatric and adult patients and may be related to chemical structure and intrinsic characteristics of the product rather than its effect on ammonia control.

Ammonia control and neurocognitive outcome among urea cycle disorder patients treated with glycerol phenylbutyrate.

UNLABELLED: Glycerol phenylbutyrate is under development for treatment of urea cycle disorders (UCDs), rare inherited metabolic disorders manifested by hyperammonemia and neurological impairment. We report the results of a pivotal Phase 3, randomized, double-blind, crossover trial comparing ammonia control, assessed as 24-hour area under the curve (NH3 -AUC0-24hr ), and pharmacokinetics during treatment with glycerol phenylbutyrate versus sodium phenylbutyrate (NaPBA) in adult UCD patients and the combined results of four studies involving short- and long-term glycerol phenylbutyrate treatment of UCD patients ages 6 and above. Glycerol phenylbutyrate was noninferior to NaPBA with respect to ammonia control in the pivotal study, with mean (standard deviation, SD) NH3 -AUC0-24hr of 866 (661) versus 977 (865) µmol·h/L for glycerol phenylbutyrate and NaPBA, respectively. Among 65 adult and pediatric patients completing three similarly designed short-term comparisons of glycerol phenylbutyrate versus NaPBA, NH3 -AUC0-24hr was directionally lower on glycerol phenylbutyrate in each study, similar among all subgroups, and significantly lower (P < 0.05) in the pooled analysis, as was plasma glutamine. The 24-hour ammonia profiles were consistent with the slow-release behavior of glycerol phenylbutyrate and better overnight ammonia control. During 12 months of open-label glycerol phenylbutyrate treatment, average ammonia was normal in adult and pediatric patients and executive function among pediatric patients, including behavioral regulation, goal setting, planning, and self-monitoring, was significantly improved. CONCLUSION: Glycerol phenylbutyrate exhibits favorable pharmacokinetics and ammonia control relative to NaPBA in UCD patients, and long-term glycerol phenylbutyrate treatment in pediatric UCD patients was associated with improved executive function (ClinicalTrials.gov NCT00551200, NCT00947544, NCT00992459, NCT00947297). (HEPATOLOGY 2012).

Novel protocol including liver biopsy to identify and treat CD8+ T-cell predominant acute hepatitis and liver failure.

In the majority of children with ALF, the etiology is unknown and liver transplantation is often needed for survival. A patient case prompted us to consider that immune dysregulation may be the cause of indeterminate acute hepatitis and liver failure in children. Our study includes nine pediatric patients treated under a multidisciplinary clinical protocol to identify and treat immune-mediated acute liver injury. Patients with evidence of inflammation and no active infection on biopsy received treatment with intravenous immune globulin and methylprednisolone. Seven patients had at least one positive immune marker before or after treatment. All patients had a CD8+ T-cell predominant liver injury that completely or partially responded to immune therapy. Five of the nine patients recovered liver function and did not require liver transplantation. Three of these patients subsequently developed bone marrow failure and were treated with either immunosuppression or stem cell transplant. This series highlights the importance of this tissue-based approach to diagnosis and treatment that may improve transplant-free survival. Further research is necessary to better characterize the immune injury and to predict the subset of patients at risk for bone marrow failure who may benefit from earlier and stronger immunosuppressive therapy.

Immunophenotyping of peripheral eosinophils demonstrates activation in eosinophilic esophagitis.

BACKGROUND AND AIM: Eosinophilic esophagitis (EoE) is a chronic inflammatory disorder characterized by upper gastrointestinal symptoms and the presence of high numbers of eosinophils in the esophagus. Although eosinophils in the esophagus have been found to be activated in subjects with EoE, detailed studies of intracellular signaling pathways involved in the mechanism of activation of eosinophils in EoE have heretofore been limited. The aim of the study was to assess whether any surface molecules or transcription factors are activated in peripheral eosinophils in subjects with EoE. METHODS: Eosinophils and CD3+ lymphocytes were identified directly from 50 µL of whole blood of EoE and control subjects. Using Hi-FACS, levels of surface activation markers, including CD66b, and intracellular phosphoepitopes, including phosphorylated forms of signal transducer and activator of transcription (phospho-STAT) 1 and 6, were measured within each cell subset. RESULTS: Levels of surface CD66b as well as levels of intracellular phospho-STAT1 and phospho-STAT6 in peripheral blood eosinophils were significantly higher for untreated subjects with EoE vs healthy controls (P < 0.05). Levels of phospho-STAT1 and phospho-STAT6 in peripheral blood eosinophils were lower in subjects with EoE on therapy versus untreated subjects with EoE (P < 0.05). CONCLUSIONS: Levels of phospho-STAT1 and phospho-STAT6, transcription factors involved in inflammatory processes, were both significantly higher in peripheral eosinophils from untreated (ie, newly diagnosed) subjects with EoE versus subjects with EoE on therapy, healthy controls. Blood-based measurements of CD66b and phospho-STAT levels in peripheral eosinophils may be beneficial for identifying EoE.

Analysis of clinical variables associated with tolerance in pediatric liver transplant recipients.

Tolerance has been defined as stable graft function off IMS. We reviewed the data of 369 pediatric liver transplant patients to examine demographic differences that may have a PV of pediatric LT tolerance. Of the 369 patients, 280 patients were stable with detectable blood levels of IMS agents and with good graft function without biopsy proven REJ > 1 yr posttransplantation, 18 patients were noted to be TOL off IMS, 27 patients were taking MIS with drug levels below detectable range by standard laboratory parameters, and 44 patients developed one or more episodes of biopsy proven acute or chronic REJ > 1 yr post-transplantation. Variables, including percentage of biliary atresia, type of transplanted organ, history of EBV infection, patient and donor gender, and ABO blood type mismatch between recipient and donor did not have PV of tolerance. Average age in years was 1.37 ± 1.53 (0.3-4.9) for TOL, 1.14 ± 0.89 (0.4-3.1) for MIS and 3.35 ± 4.45 (0.3-16) for REJ. Age difference of TOL/MIS vs. REJ was significant (p =0.002) and TOL vs. REJ was significant (0.01). Age at the time of transplantation is an important predictor in the development of pediatric LT tolerance.