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Aim: To determine how changes in tacrolimus (TAC) immunosuppression clinical practice, in the first 15 days post liver transplantation (LT) and across a decade, impact a clinical covariate - pharmacokinetic (PK) model, developed in data from 1998, thus testing its utility in dose individualization across time. Patient cohorts from 1998 (Reference: R-1998) and 2007 (EVALUATION: E-2007) were compared., Methods: Analysis of monitoring observations (Cmin and Cmin/dose) and the biochemical variables aspartate aminotransferase (AST), hematocrit (HCT), albumin (ALB) and serum creatinine (SCr) was done for 0 - 3 and 4 - 15 days post transplantation (PT). The population PK model developed for R-1998 [1] was re-evaluated for the two cohorts., Results: Significant differences in R-1998 vs. E-2007 existed in Cmin and Cmin/dose and in covariates AST (as hepatic function marker) and SCr (as toxicity marker). E-2007 had lower levels of Cmin and Cmin/dose (1/CL), lower AST with faster recovery and lower variability in Cmin/dose for similar dose. AST was a covariate on CL/F in the 0 - 3 day PT period. In 4 - 15 days PT for E-2007, low levels of HCT and ALB as CL/F predictors confirmed a subgroup with higher CL/F (23.8 l/h vs. 19.3 l/h). The R-1998 model's original structure was confirmed., Conclusions: Ten years of use of TAC shows gain in therapeutic targeting efficiency, due to improvement in LT methods, knowledge of the drug and consideration of PK steady state. The remaining uncertainty with TAC monitoring in LT can be resolved with application of PK principles combined with patients' diosyncrasies in the model developed for TAC dose individualization in R-1998. The applicability of the model as nucleus in Bayes individualization remains intact across a decade.

Purpose: To define and validate a pharmacokinetic (PK) model for tacrolimus (TAC) that includes patient pathophysiology and has clinical applicability in the first 2 weeks post-liver transplantation (PLT)., Methods: Routine monitoring records [dose, trough levels (C(min)), demographics, biochemistry] from 75 patients treated with TAC (Prograf®) PLT were used to develop a population PK model (employing NONMEM®) testing for predictors of oral clearance (CL/F) according to bedside evidence and primarily with aspartate aminotransferase (AST), albumin (ALB), and hematocrit (HCT). Patients were catergorized into subgroups with above and below "normal" thresholds for AST (500 U/L), ALB (2.5 g/dL), and HCT (28 %), respectively. The model was validated with ten patients from the same period and 15 more recent patients. An empirical Bayes method was developed and applied to the prediction of individual profiles serving as a dose adjustment tool., Results: The number of days PLT (Days PLT) was a key variable during the first 2 weeks, with a dichotomy in the mono-compartmental parameters for 0-3 Days PLT and 4-15 Days PLT. During 0-3 Days PLT, AST levels, indicative of allograft functionality (and TAC metabolism), were crucial predictors of elimination. Three groups were identified with the following clearances: CL/F₀₋₃ = 8.93 L/h for AST ≥ 500 U/L and CL/F₀₋₃ = 11.0 L/h for AST <500 U/L. During 4-15 Day PLT, low values of ALB (<2.5 g/dL) and HCT (<28 %) combined were determinant of a patient subgroup with a tendency to underexposure and complexity in empirical dose adjustment. The CL/F₄₋₁₅ = 25.1 L/h for this subgroup compared to CL/F₄₋₁₅ = 17.1 L/h for the others in that period. The elimination half-life for individual patients varied over tenfold so that a large number of subjects were not at steady state, making the use of a PK model necessary to achieve rapidly and safely the target concentration for TAC in LT. Validation of the model demonstrated that both bias and precision were within acceptable limits., Conclusion: For TAC therapy, covariate models using mixed effects methods are most useful when combined with patient-specific biochemical assays as well as clinical evidence. In such cases, the observed C(min) and Bayes methods can provide the most likely individual PK parameters, hence the optimal next dose to reach individualized target levels for each patient.

Purpose: To explore the main factors that make it difficult to empirically monitor tacrolimus (TAC) in the early period post-liver transplantation (LTx), with a specific focus on those aspects related to patient idiosyncrasy and clinical status as well as to the pharmacokinetic (PK) assumptions on which drug individualization in clinical practice is based., Methods: Retrospective monitoring data from 75 de novo liver transplant patients treated with twice daily with TAC and followed for up to 15 days were analyzed. An extensive battery of laboratory measurements were available. Dose adjustment was performed empirically using trough levels (C(min)). The population was separated into two major background groups according to low or high values of aspartate aminotransferase (AST) (Group 1 and 2, respectively) based on AST measurements made during the first 4 days post-LTx. Each of these two major groups was then further subdivided into two subgroups based on elevated (Groups 1A, 2A) or reduced (Groups 1B, 2B) combined albumin (cut-off 2.5 g/dl) and hematocrit (cut-off 28%)., Results: The C(min)/Dose ratio [inversely proportional to systemic clearance (CL)] had a variability [coefficient of variation (CV) >80%) that was incongruently higher for the ratio than for C(min) and Dose separately. This was attributed to most patients not being at steady state or physiologically stable in the early post-LTx period. Group 1 patients were more predictable than Group 2 patients, who were responsible for the variability in the ratio. C(min) was lower in the reduced ALB and HCT patient groups when AST conditions were similar (1A vs. 1B and 2A vs. 2B), likely due to increased TAC metabolic clearance (reduced C(min)/Dose). This situation existed for two periods: 0-15 days post-LTx and 4-15 days post-LTx observations. Group 2A patients were the main source of the paradoxical variability in C(min)/Dose (higher ratio of 2.7; CV = 100%), suggesting a lower clearance and difficulty in the recovery of stability. In contrast, Group 2B patients had the lower ratio (1.4; 47%) but required the highest number of dose adjustments as the variability was hard to identify clinically. Group 1A patients were the most predictable empirically. When observations from 15 new patients who entered the clinic in 2007 and 2008 were used for the analysis, the same sub-groups existed in the same proportions in both years., Conclusion: The difficulty in empirical dose adjustment of TAC is associated to the inevitable non-fulfillment of PK assumptions early post-LTx and also to the inherent complexity of the clinical condition, leading to increased uncertainty for the clinician regarding dose selection. Identifying these sub-categories provides a rational means of classifying patients akin to a phenotype. The complexity of the kinetics in LTx and TAC treatment does not invalidate C(min) as a biomarker, but a Bayes algorithm including a full PK structure and these covariates would be optimal.

Aim: To analyze the benefits of Split (for adult and for child) in liver transplantation., Patient/methods: 1) Analysis of the waiting list mortality estimated on 228 inclusions for transplant since January 2004 to December 2008.2) Impact of the variant techniques (living-related donor and split) on the waiting list mortality in our patients. 3) Analysis of the outcome of 33 split livers which allowed to perform 66 transplants (1994-2008)., Results: Estimated as number of patients by 1,000 candidates by year of exposure, the waiting list mortality was 110 in children older than 5 year old, 180 in children from 2 to 5 year-old, 90 in children between 1 and 2 year-old and 510 in younger than 1 year (p<0.05 for the last group). 36/66 split grafts were implanted by our group. Five grafts were lost, 3 due to retransplantation and 2 due to death. Overall patient/graft survival alter 10 years of follow-up was 94.5% and 85.1%, respectively. The rest of the grafts (n=30), were used in other hospitals, and 4 were lost in the early postoperative period. Since the beginning of the study, 85.4% of children between 1 and 2 years, received a living-donor or a split graft, as only 59.9% in the younger than 1 year-old group., Conclusion: Our results absolutely justify the ethics of split liver transplantation for an adult and a child. Despite other factors, the benefits of the variant techniques in the 1-2 year-old group are obvious. Up to 60% optimization with these techniques in children younger than 1 year would not be yet enough in order to decrease the mortality waiting list down to that of the rest of the groups.

Aim: Liver pediatric transplantation finds in the lack of donors its main limitation. An alternative in those cases is split liver grafts from bigger donors., Patients and Method: We performed a retrospective study of 56 hepatic split transplants performed between 1994 and 2007. Twenty-nine children were transplanted with a median age and weight of 1.8 years old (0.3-9) and 9.7 kg (6.2-23). In 16 cases (53.3%) liver transplant was performed in emergency situation. In one patient we performed a combined transplant (liver-kidney) and in another patient it was a second transplant due to primary graft failure after receiving an hepatointestinal allograft. Type of grafts used were: lateral left segment (n=26), extended lateral left segment (n=1) and extended right liver (n=3). Median donor age and weight were 20 years old (8-44) and 60 kg (24-80). We studied patient and graft survival (Kaplan Meier), perioperative factors, complications and net rate of early complications in adults recipients., Results: Patient survival was 96.7% after 6 months, 1 year, 5 years and 10 years. Id for grafs 86.7%. Two grafts were lost due to arterial thrombosis, one due to primary non function and another due to recipient death secondary to a sepsis. Five children had major biliary complications and 2 of them developed multiple intrahepatic stenoses, one of them being on waiting list for retransplant. Early graft lost (retransplant or death before leaving the hospital) occurred in 4 out of the 25 grafts transplanted in other centers (25 adults, 1 kid); all of them occurred in the initial period (1994-2001)., Conclusions: Even though it is clearly documented that benefit of transplant (measured in years of life won) is very good after split transplantation, nowadays criteria for organ allocation in Spain do not allow a more extensive diffusion of this technique and it is confined to urgent transplant. Even in those cases, results after split transplantation are excellent. Without this possibility our pretransplant mortality would be much higher.

Aim: Even though Spain has the highest donation rate in the world, our needs cannot be satisfied, specially in younger children. Living-related donor transplant is an alternative in those cases., Patients and Method: We performed a retrospective study of 57 living-related donor transplants performed in our hospital between June 1993 and December 2007. Median age and weight were 1.2 years old (0.5-14.8) and 8.5 kg (5-62). Indications for transplant were as follow: biliary atresia in 42 cases (73.7%), hepatic tumor in 8 (14%) and others in 7 patients. Type of graft was: monosegment (n=1), left lateral segment (n=45), extended left lateral segment (n=5), left liver (n=4), right liver (n=2). We studied the following factors: graft and patient survival (Kaplan Meier), perioperative conditions, complications, causes of graft lost, donor complications and technique difficulties., Results: Patient survival at 3 months, 1 year, 5 years and 10 years was 98.2%, 98.2%, 95% and 95% respectively. Three grafts werelost due to arterial thrombosis, two due to rejection, one due to portal thrombosis and three due to other causes. Complications were as follow: biliary fistula in the cut surface (6), biliary anastomosis complications (6), cut surface abcess (1), portal stenosis (2), suprahepatic stenosis (1) and intestinal perforation (2). Most common complication in donors was biliary leak (4). Among the technique difficulties, 8 patients needed major reconstruction of suprahepatic vein; 4 needed complex portal reconstruction, 6 patients had double biliary tract and 4 patients needed multiple arterial anastomosis. Wall closure was delayed (Goretex) in 35% of cases (20)., Conclusions: Despite technical complications, results after living-related donor transplantation are excellent. It is particularly favourable for children with low weight, since Spanish policy for organ allocation does not make easy to find an adecuate donor in short periods of time. Without living-related donor transplantations, mortality pretransplant would be much higher.

Introduction: Several variant techniques have been developed as alternatives to whole liver transplantation to improve size matching, timing, or simply to increase the pool of donors. The aim of this study was to assess the requirements of these techniques and their outcomes in a pediatric transplant program., Patients and Method: A retrospective analysis of children on the waiting list in the last 4 years was carried out. Data of patients who died while on the waiting list (WL) were recorded. Transplanted patients were divided according to the type of graft: whole liver, split, living donor and reduced liver. The analyzed outcome variables were: age, weight, UNOS status, cause of liver failure, complications and graft and patient survival. Comparisons between types of graft were performed by using Kaplan-Meier, log-rank, chi (2) and Kruskal-Wallis tests., Results: During the period studied, 116 children were listed for liver transplantation. Of these 116 children, nine (7.7 %) died after a mean period of 40.5 (5-175) days waiting for a suitable graft. Their median age at inclusion was 214 (35-1607) days, and median weight was 7.2 (12.3-3.6) kg. The cause of liver failure in this group was: 1 hemochromatosis, 1 hepatoblastoma, 2 biliary atresia, 2 acute liver failure, 2 primary non-function (PNF) and 1 chronic rejection. Liver transplantation was performed in 103 children: 25 (24 %) whole livers, 17 (16.5 %) split, 29 (28 %) living donor, 32 (31 %) reduced and 4 remain on the waiting list. Recipient age and weight were significantly lower in those receiving split and living donor than in those who given whole livers. Patient and graft survival were similar in all groups although there was a trend to lower graft survival in patients receiving whole livers. More than 50 % of patients with UNOS status I received a split graft and 5/6 children with hepatoblastoma underwent living donor transplantation. There were no differences in the rate of acute vascular complications, but long-term biliary complications were more frequent in split and living donor grafts., Conclusions: As long as the goal of zero mortality for children on the waiting list is not achieved, variant techniques will be necessary in pediatric liver transplantation programs. Split and living donor were employed mostly to treat younger children and particularly those with a higher UNOS status. Children with tumors were treated mainly with living donor grafts. Variant techniques, which are absolutely necessary in a pediatric program, need to be improved in order to avoid long-term biliary complications.

Objective: To analyse our results on liver transplantation (LTX) in primitive malignant unresectable liver tumours in children and discussing its controversial indications in order to our experience., Methods/patients: We report 12 patients with ages ranging from 6 months to 14 years old. They had hepatoblastoma (11) and fibrolamellar hepatocelullar carcinoma (1) without cirrhosis. LTX was considered as primary treatment in 10 patients (PRETEXT IV or any grade if extension to retrohepatic cava vein, 3 hepatic veins or porta vein were assessed) and as rescue therapy after recurrence (1) or persistence of unresectable macroscopic rests (2). One of the patients who underwent a LTX as primary therapy had lung metastases previously resolved with chemotherapy. We used entire liver (5), left lateral segment from cadaveric donor (3), live related donor (3, 2 segments II-III and 1 right liver) and left lateral segment from split (1). All children received chemotherapy prior and post-transplantation following SIOPEL protocol. OUTCOMES ANALYSED: Procedure tolerance, survival, recurrence rate, disease-free period and risk factors for adverse evolution., Results: All patients overcame the LTX and no early loss of the graft was assessed. 2 patients died because of tumoral relapse, 1 after primary LTX and 1 after rescue LTX (survival rate of both groups 90% vs 50%). Graft and patients 1-year, 3-year, 5-year and 14-year survival were 91%, 91%, 82% and 82% respectively. The boy who presented lung metastases developed new ones one year after LTX that were removed and he actually is free of disease. The disease-free period has a probability for 1, 3 and 5 years of 91%, 75% and 75%. Tumoral tissue persistence is the only risk factor for an adverse evolution in our series., Conclusions: LTX is possible therapeutic approach for unresectable malignant liver tumours. It provides better results as a primary treatment than as a rescue one, being these outcomes comparable to those from resectable tumours. A right staging and referring patients to an expertise centre contribute to optimize results. LTX for patients presenting with lung metastases could be a controversial option. Live-related donor transplantation is an excellent alternative to avoid disease progression during cadaveric waiting list.

Background: Orthotopic liver transplantation (OLT) in children younger than one year is associated to higher waiting list mortality and alternative graft sources are required. We present our experience with this particular group of age., Methods: Infants younger than one year who received an OLT between 1986 and 2005 were reviewed focused on graft and children survival depending on period and type of graft. Periods were 1:1986-1995; 2:1996-2000 and 3:2001-2005. We also evaluate cold ischemia time (CIT), graft lost causes and differences between CIT and anhepatic time (AT) depending on graft type., Results: Eighty-three children received 103 OLT. Liver transplant indications were 59 (72%) biliary atresia, 8 (10%) metabolic causes, 6 (8%) liver failure, 3 (4%) cirrhosis and 7 (6%) miscelaneous. Patient and graft survival after 5 years was increased depending on period: 45% and 65% on period 1, 70% and 80% on period 2, 94% y 97% on period 3 (p < 0.0198). Thirty-seven grafts were reduced lobes (42%); 8 (21%), 17 (45%) and 12 (35%) during periods 1, 2 and 3 respectively and their 5 years survival rate was 68%. Twenty-four were whole grafts (31%); 11 (45%), 10 (45%) and 3 (14%) during periods 1, 2 and 3 and their 5 years survival rate was 63%. Fourteen grafts were living-related donor (16%); 1 (7%), 2 (14%) and 11 (79%) during periods 1, 2 and 3 and their 5 years survival rate was 93%. Eight (11%) were split; 0, 1 (12%) and 7 (90%) during periods 1, 2 and 3 and their 5 years survival rate was 100%. Average CIT depending on graft was: living donor 5,5 hours (IQR: 4-7), split 6,1 hours (IQR: 5-8), whole 9.2 hours (IQR: 6-11) and reduced 8.5 hours (IQR: 6-11) (p < 0.05). Average AT depending on graft was: living donor 1 hour (IQR: 0.5-1.5), split 1 hour (IQR: 0.5-1.4), whole 1,1 hours (IQR: 0.5-1.5) (p > 0.1). Twenty-four grafts were lost (28%): 10 (41%) were surgical related causes and 6/10 (60%) of them were whole grafts., Conclusions: Survival rates in children younger than one year are similar to another groups of age. There was a significant increase on graft survival according to transplantation group experience. A higher rate of graft lost is associated to whole grafts. Most frequent reasons of graft lose were related to sepsis and immunosuppresion. A significant shortening of CIT is observed in related living donor and split grafts.

Unlabelled: We examined whether the results in living-related hepatic transplantation (LRLT) are better than those from a cadaveric donor (CDLT)., Material and Methods: The last 27 consecutive LRLT, performed from 1998 to 2005, were compared with 27 CDLT matched for age, weight, date, and diagnosis. Grafts in LRLT group were left lateral segment (n = 22), left lobe (n = 3), and right lobe (n = 2). In the CDLT group, the grafts were split in situ (n = 10), hepatic reduction (n = 9) and whole liver (n = 8). We analyzed the actuarial survivals (grafts and children), retransplantation, primary nonfunction, initial graft malfunction (liver enzymes >2000 U/L), surgical complications, rejection, and resource consumption., Results: Patient survivals at 6 months, 1 year, and 5 years were 100%, 96%, and 96% in LRLT and 100%, 100%, and 100% in CDLT (P = NS). Graft survivals were 93%, 89%, and 89% versus 96%, 96%, and 96%, respectively (P = NS). Complications were biliary complications (LRLT, 25% vs CDLT, 3%; P = .021); portal vein thrombosis (LRLT, 7% vs CDLT, 3%; NS), and hepatic artery thrombosis (LRLT, 0% vs CDLT, 3%; NS). The overall incidence of acute rejection was slightly higher (NS) in LRLT (LRLT, 18% vs CDLT, 11%; NS). Liver enzyme levels were higher in the CDLT group, but initial malfunction rate was not statistically different. Regarding resource consumption: blood product needs were higher in LRLT (P < .05) and hospital stay and ICU stay were longer, although not significantly, among LRLT., Conclusions: The results in LRLT among children are similar to those obtained in CDLT. We found a trend towards less initial graft malfunction in LRLT. Blood product needs were higher in LRLT. Hospital and ICU stay were longer, but not significantly different in LRLT. The benefits of LRLT are saving a scarce resource: a cadaveric donor liver graft.

Aim: To analyze independent risk factors associated with poor graft and patient survival in a series of 292 pediatric liver transplants (PLT) performed in 234 children during a 15 years period. MATERIAL AND METHODS. 1. Univariate graft and patient survival analysis in 45 variables related to pretransplant patient status, surgical technique and donor conditions. 2. Variables found with univariate analysis to be associated with outcome were entered into a stepwise backward proportional hazard model (Cox), to determine independent prediction of outcome., Results: 11 variables influence the graft survival: recipient age, z-score recipient height, UNOS status, recipient and donor weight, transplant for immune hepatitis, platelet transfusion during the transplant, blood index > 4 during the surgery, type of arterial reconstruction, retransplantation and era of the transplant (first er: 1986-1990; 2nd. era: 1991-1995; 3rd. era: 1996-2000). Four of those variables are independent in the multivariate analysis: UNOS 1 status (Odds Ratio, OR = 2.82, 95% confidence interval = 1.36-5.85), recipient < 3 years (OR = 3.76, 95% CI = 2.13-6.63), transplants for autoimmune hepatitis and era (OR of first and second versus third era respectively 3.93 and 2.81). The independent variables influencing the patient survival were: children receiving more than one graft children less than 3 years old and transplant era., Conclusions: Liver transplant in small children is associated with an increased risk of graft loss and patient dead. The experience of the hospital in pediatric liver transplantation improves the results, particularly in small children.

Aim: The aim of this study was to analyze the results of living donor in a pediatric liver transplantation program., Patients: Twenty-six living donor liver transplantations were performed in children from 0.5 to 14.8 years of age. The main indication was biliary atresia (72%) followed by tumors (2 hepatoblastomas and 1 hepatocarcinoma). Left lateral segments were used in 23 (1 transformed into a monosegment), 1 left lobe was used in 1, and right lobes were used in 2. Arterial reconstruction employed saphenous venous grafts in the first 3 cases and end-to-end anastomoses with a microsurgical technique in the following 22 cases., Results: There has been no major morbidity in the donors, with a median hospitalization of 6 days. Four grafts have been lost; 2 in the first 3 cases. In only 1 case, the graft loss was related to the procedure saphenous venous graft thrombosis). Early biliary complications were frequent (23%). Six month, 1 year, and 5 year graft and patient survival rates were 91%, 85%, and 85% and 100%, 96%, and 96%, respectively., Conclusions: Living donor liver transplantation is an excellent option for transplantation in children.