Pediatric Candidates Research Articles

Impact of Acuity Circles on Outcomes for Pediatric Liver Transplant Candidates.

In December 2018, United Network for Organ Sharing approved an allocation scheme based on recipients' geographic distance from a deceased donor (acuity circles [ACs]). Previous analyses suggested that ACs would reduce waitlist mortality overall, but their impact on pediatric subgroups was not considered. We applied Scientific Registry of Transplant Recipients data from 2011 to 2016 toward the Liver Simulated Allocation Model to compare outcomes by age and illness severity for the United Network for Organ Sharing-approved AC and the existing donor service area-/region-based allocation schemes. Means from each allocation scheme were compared using matched-pairs t tests. During a 3-year period, AC allocation is projected to decrease waitlist deaths in infants (39 versus 55; P < 0.001), children (32 versus 50; P < 0.001), and teenagers (15 versus 25; P < 0.001). AC allocation would increase the number of transplants in infants (707 versus 560; P < 0.001), children (677 versus 547; P < 0.001), and teenagers (404 versus 248; P < 0.001). AC allocation led to decreased median pediatric end-stage liver disease/model for end-stage liver disease at transplant for infants (29 versus 30; P = 0.01), children (26 versus 29; P < 0.001), and teenagers (26 versus 31; P < 0.001). Additionally, AC allocation would lead to fewer transplants in status 1B in children (97 versus 103; P = 0.006) but not infants or teenagers. With AC allocation, 77% of pediatric donor organs would be allocated to pediatric candidates, compared to only 46% in donor service area-/region-based allocation (P < 0.001). AC allocation will likely address disparities for pediatric liver transplant candidates and recipients by increasing transplants and decreasing waitlist mortality. It is more consistent with federally mandated requirements for organ allocation.

Outcomes After Declining Increased Infectious Risk Kidney Offers for Pediatric Candidates in the United States.

Kidneys from infectious risk donors (IRD) confer substantial survival benefit in adults, yet the benefit of IRD kidneys to pediatric candidates remains unclear in the context of high waitlist prioritization. Using 2010-2016 Scientific Registry of Transplant Recipients data, we studied 2417 pediatric candidates (age <18 y) who were offered an IRD kidney that was eventually used for transplantation. We followed candidates from the date of first IRD kidney offer until the date of death or censorship and used Cox regression to estimate mortality risk associated with IRD kidney acceptance versus decline, adjusting for age, sex, race, diagnosis, and dialysis time. Over the study period, 2250 (93.1%) pediatric candidates declined and 286 (11.8%) accepted an IRD kidney offer; 119 (41.6%) of the 286 had previously declined a different IRD kidney. Cumulative survival among those who accepted versus declined the IRD kidney was 99.6% versus 99.4% and 96.3% versus 97.8% 1 and 6 years post decision, respectively (P = 0.1). Unlike the substantial survival benefit seen in adults (hazard ratio = 0.52), among pediatric candidates, we did not detect a survival benefit associated with accepting an IRD kidney (adjusted hazard ratio: 0.791.723.73, P = 0.2). However, those who declined IRD kidneys waited a median 9.6 months for a non-IRD kidney transplant (11.2 mo among those <6 y, 8.8 mo among those on dialysis). Kidney donor profile index (KDPI) of the eventually accepted non-IRD kidneys (median = 13, interquartile range = 6-23) was similar to KDPI of the declined IRD kidneys (median = 16, interquartile range = 9-28). Unlike in adults, IRD kidneys conferred no survival benefit to pediatric candidates, although they did reduce waiting times. The decision to accept IRD kidneys should balance the advantage of faster transplantation against the risk of infectious transmission.

Changes in Pediatric Spine Surgery Patterns Over the Last 10 Years Among ABOS Part II Candidates.

A retrospective review of prospectively collected data. Our purpose was to evaluate the volume of pediatric spine cases being done by surgeons applying for American Board of Orthopaedic Surgeons (ABOS) certification. Pediatric orthopedic surgery has become increasingly subspecialized over the past decade. Data were reviewed from the ABOS for surgeons undergoing part II of ABOS certification between 2004 and 2014. Applicants were divided into pediatric orthopedic surgeons and spine surgeons based on their self-declared subspecialty for the ABOS Part II examination. A total of 102,424 cases were reviewed to identify spine cases performed on patients <18 years old. Between 2004 and 2014, the total number of ABOS part II pediatric candidates increased significantly, from a low of 15 to a high of 44 (r = 0.68, P = 0.001). During this time frame, there has been no significant increase in the total number of pediatric spine cases reported (r = 0.09, P = 0.19). In 2004, 46.5% (33/71) of the pediatric spine cases were done by spine surgeons, which decreased to 17.3% (28/162) in 2014. Conversely in 2004, 53.5% (38/71) of pediatric spine cases were done by pediatric orthopedists, which increased to 82.7% (134/162) in 2014. The number of pediatric candidates performing pediatric spine cases decreased 35% from 2004 to 2014, but the percentage performing >20 spine cases during their candidate year has increased from 0% to 7% (r = 0.31, P = 0.04). The share of pediatric spine surgeries performed by pediatric candidates has increased from 54% in 2004 to 83%, with a corresponding fall in the share surgeries performed by spine candidates (47% to >17%). The percentage of pediatric candidates performing more than 20 spine cases/year increased from 0% to 7%, reflecting a trend of spine subspecialization within pediatric surgery. 3.

Improved Survival Following Living Donor Liver Transplantation for Pediatric Acute Liver Failure: Analysis of 20 Years of US National Registry Data.

This study estimated the utility of technical variant grafts (TVGs), such as split/reduced liver transplantation (SRLT) and living donor liver transplantation (LDLT), in pediatric acute liver failure (PALF). PALF is a devastating condition portending a poor prognosis without liver transplantation (LT). Pediatric candidates have fewer suitable deceased donor liver transplantation (DDLT) donor organs, and the efficacy of TVG in this setting remains incompletely investigated. PALF patients from 1995 to 2015 (age <18years) were identified using the Scientific Registry of Transplant Recipients (n=2419). Cox proportional hazards model and Kaplan-Meier curves were used to assess outcomes. Although wait-list mortality decreased (19.1% to 9.7%) and successful transplantations increased (53.7% to 62.2%), patients <1year of age had persistently higher wait-list mortality rates (>20%) compared with other age groups (P<0.001). TVGs accounted for only 25.7% of LT for PALF. In the adjusted model for wait-list mortality, among other factors, increased age (subhazard ratio [SHR], 0.97 per year; P=0.020) and access to TVG were associated with decreased risk (SHR, 0.37; P<0.0001). LDLT recipients had shorter median waiting times compared with DDLT (LDLT versus DDLT versus SRLT, 3 versus 4 versus 5days, respectively; P=0.017). In the adjusted model for post-LT survival, LDLT was superior to DDLT using whole grafts (SHR, 0.41; P=0.004). However, patient survival after SRLT was not statistically different from DDLT (SHR, 0.75; P=0.165). In conclusion, despite clear advantages to reduce wait-list mortality, TVGs have been underutilized in PALF. Early access to TVG, especially from LDLT, should be sought to further improve outcomes.

Predicting chance of liver transplantation for pediatric wait-list candidates.

Information about wait-list time has been reported as one of the single most frequently asked questions by individuals awaiting a transplant but data regarding wait-list time have not been processed in a useful way for pediatric candidates. To predict chance of receiving a DDLT, we identified 6471 pediatric (<18years), non status-1A, liver-only transplant candidates between 2006 and 2017 from the SRTR. Cox regression with shared frailty for DSA level effect was used to model the association of blood type, weight, allocation PELD and MELD, and DSA with chance of DDLT. Jackknife technique was used for validation. Median (interquartile range) wait-list time was 100 (34-309)days. Non-O Blood type, higher PELD/MELD score at listing, and DSA were associated with increased chance of DDLT, while age 1-5years and 10-18years was associated with lower chance of DDLT (P<0.001 for all variables). Our model accurately predicted chance of transplant (C-statistic=0.68) and was able to predict DDLT at specific follow-up times (eg, 3months). This model can serve as the basis for an online tool that would provide useful information for pediatric wait-list candidates.

Frequency of whole-organ in lieu of split-liver transplantation over the last decade: Children experienced increased wait time and death.

Organ shortage is a barrier to liver transplantation (LT). Split LT (SLT) increases organ utilization, saving 2 recipients. A simulation of Organ Procurement and Transplantation Network/United Network for Organ Sharing data (2007-2017) was performed to identify whole-organ LT grafts (WLT) that met the criteria for being splittable to 2 recipients. Waitlist consequences presented. Deceased donor (DD) livers transplanted as whole organs were evaluated for suitability to split. Of these DD organs, we identified the adolescent and adult recipients of WLT who were suitable for SLT. Pediatric candidates suitable to share the SLT were ascertained from DD match-run lists, and 1342 splittable DD organs were identified; 438 WLT recipients met the criteria for accepting a SLT. Review of the 438 DD match-run lists identified 420 children next on the list suitable for SLT. Three hundred thirty-three children (79%) underwent LT, but had longer wait-times compared to 591 actual pediatric SLT recipients (median 147days vs 44days, P < 0.001). Thirty-three of 420 children died on waitlist after a mean 206days (standard deviation 317). Sharing organs suitable for splitting increases the number of LT, saving more lives. With careful patient selection, SLT will not be a disadvantage to the adult recipients. With a children-first allocation scheme, SLT will naturally increase the number of allografts because adult organs are too large for small children.

Dose-Dependent Response to Desensitization in Pediatric Heart Transplant Candidates Assessed by Single Antigen Bead Technology

Purpose The efficacy of desensitization, the process of reducing anti-HLA antibodies in sensitized patients awaiting heart transplantation (HT), is unclear in pediatric HT candidates. Methods To evaluate the impact of DS in pediatric HT candidates, we performed a retrospective analysis of all patients listed for HT between 1/1/10 - 6/30/18 at our institution. Sensitized patients were defined as having a panel reactive antibody (PRA) ≥ 10% and ≥1 strong positive antibody with mean fluorescence intensity (MFI) ≥ 5500. Patients were identified as nonsensitized (NS, n = 55), sensitized but no therapy (S-NT, n = 18), and sensitized undergoing desensitization therapy (S-DS, n = 14). Response to desensitization was defined as ≥25% reduction in the MFI for ≥90% of strong positive antibodies for whom follow up PRA testing was performed prior to delisting, HT, or death (n = 13). Results DS consisted of IVIG and rituximab for all patients; 2 also received bortezomib. DS responders, defined by reduction in antibody burden (n = 8), received on average more doses of IVIG than nonresponders (9 vs 3, p = 0.04). All five S-DS patients that received HT during the study period had a negative flow crossmatch (FXM) and most (80%) would have had a positive FXM with historical serum. All S-DS had history of single ventricle congenital heart disease and homograft exposure. Prior VAD was associated with sensitization severity (mean positive antibodies 75 vs 26, p = 0.01) but not response to DS, and history of ECMO was associated with neither. S-DS compared S-NT were on average more sensitized (mean number of high MFI antibodies 45 vs 21, p = 0.04), waited longer for HT (569 vs 148 days, p = 0.005), and trended towards higher waitlist mortality (36% vs 11%, p = 0.09). NS patients were less likely to have homograft exposure (p Conclusion A favorable response to DS was observed in most patients in this cohort. Homograft and VAD, but not ECMO, were associated with severity of sensitization. IVIG appears to have some benefit, with a dose-dependent effect. Post-HT outcomes for S-DS, S-NT, and NS patients were similar in this study.

Broadening ABO Incompatibility Pediatric Heart Transplantation, Even in Children 2 Years and Older

Purpose Blood type ABO incompatibility (ABOi) is becoming increasingly utilized in heart transplantation. We sought to identify whether this increase was mostly in infants or older children as well. Methods Pediatric patients ( Results From 2000-2017, there were 415 ABOi transplants completed in children up to 13 years of age. ABOi transplantation volume over time is shown in Figure 1. Of ABOi transplants, 70% (n=291) were done in North America (NA) and 28% (n=115) in Europe. The proportion of ABOi transplants was 4.6% in NA and 4.5% in Europe (p=0.87). When examined by era, this proportion has increased from 3.5% (2000-2008) to 5.3% (2009-2017), p Conclusion Willingness to accept ABOi allografts has continued to increase in the recent era, especially among pediatric candidates >2 years old. The trends in ABOi transplants are similar between NA and Europe. In the U.S., 1/5th of the recipients listed as ABOi transplant acceptable ultimately received ABOi transplant. Survival among the expanding group of ABOi pediatric heart transplant recipients compares favorably to ABO compatible transplants. These outcomes should encourage centers to use ABOi donors, particularly in select older children.

Deceased Pediatric Donor Livers: How Current Policy Drives Allocation and Transplantation.

Each year, approximately 60 children, representing 12% of waitlist candidates, die awaiting liver transplantation. The current allocation algorithm for pediatric donor livers prioritizes local/regional adults over national children. We attempted to better understand the impact of the present algorithm on pediatric candidates. We analyzed pediatric donor liver offers from 2010 to 2014. Donors and recipients were classified based on age. We mapped allocation and acceptance patterns and used subgroup analyses to explore the significance of donor service areas (DSAs) with low pediatric transplant volumes. We used Cox proportional hazard regressions to evaluate posttransplantation outcomes: 3,318 pediatric donor livers were transplanted into 3,482 recipients, and 45% (1,569) were adults. Of the 1,569 adults, 25% (390) received a pediatric organ that was never offered to children; 52% (204) of these 390 pediatric organs originated in the 37 DSAs, with ≤25 pediatric liver transplantations; 278 children died or were delisted due to illness during the same time, with higher mortality rates in the 37 DSAs (10% versus 6%, P < 0.01). Compared to adults, pediatric recipients aged <12 years had lower risks of posttransplant mortality (hazard ratio, 0.62; 95% confidence interval, 0.46-0.81; P < 0.01). Conclusions: We found that 45% of pediatric donor livers were transplanted into adults: 390 adults were transplanted with pediatric organs never offered to children, while 278 children died or were delisted due to illness, which was more apparent in DSAs with low pediatric transplant volumes; we advocate for a change to allocation policies to allow pediatric organs to be offered to national children with status 1B or Model for End-Stage Liver Disease/Pediatric End-Stage Liver Disease >15 before being offered to local/regional + circle non-status 1A adults.

Comparison of 10‐year graft failure rates after induction with basiliximab or anti‐thymocyte globulin in pediatric heart transplant recipients—The influence of race

The impact of induction therapy in pediatric heart transplantation has been uncertain. Given the risk of poor outcomes in black pediatric heart transplant recipients, we evaluated the effect on graft survival of ATG and BAS induction in black and non-black pediatric recipients. This was a retrospective analysis of pediatric candidates (aged ≤18years) who underwent heart transplantation from 2000 to 2016 identified from the UNOS database. Primary outcome was 10-year graft survival. This study included 654 patients receiving BAS, 2385 patients receiving ATG, and 2425 receiving no induction. Ten-year survival was similar for the following groups: non-black BAS (57%), non-black ATG (66%), and black ATG (51%). The black BAS group had a 10-year graft survival of 39% which was inferior on pairwise comparison to the other groups (all P values<0.001). On multivariate analysis, ATG was associated with decreased risk of graft failure when compared to no induction (HR 0.86, 95% CI 0.76-0.97, P=0.011) and had an association approaching statistical significance when compared to BAS induction (0.84, 0.7-1.01, P=0.069). This association was seen in black recipients in whom ATG was strongly associated with decreased risk of graft failure when compared to either no induction (0.65, 0.5-0.83, P=0.001) or BAS (0.64, 0.46-0.89, P=0.008) but was not seen in non-black recipients. Black pediatric heart transplant recipients who received ATG induction had an improved long-term graft survival compared to those who received BAS induction or no induction.

OPTN/SRTR 2017 Annual Data Report: Intestine.

Despite improvements in medical and surgical treatment of intestinal failure, intestine transplant continues to play an important role. In 2017, 109 intestine transplants were performed, 62 in adults and 47 in children, reflecting the changed age distribution over the past decade of candidates waitlisted for intestine and intestine-liver transplant from largely pediatric to increasing proportions of adults. In 2017, 56.0% of candidates on the intestine list at any time during the year were aged younger than 18 years, with a decrease over time in those aged younger than 6 years and an increase in those aged 6-17 years. Adults accounted for 44.0% of candidates on the list at any time during the year, with an increase since 2013 in those aged 18-34 years and a decrease in those aged 35 years or older. By age, the pretransplant mortality rate was highest for adult candidates at 7.9 per 100 waitlist-years and lowest for pediatric candidates at 3.7 per 100 waitlist-years. Patient survival varied by age and type of transplant, and was lowest for adult intestine-liver recipients (1- and 5-year survival 66.7% and 42.6%, respectively) and highest for pediatric intestine recipients (1- and 5-year survival 86.2% and 75.4%, respectively).

“It Can’t Be the Dialysis that Kills the Child…” Partnering Pediatric Palliative Care with Care for Children with End-Stage Renal Disease (TH366)

•Explain key issues in end-stage renal disease in the pediatric population.•Summarize dialysis care, including the various forms, eligible populations, contraindications, and complications.•Identify opportunities and challenges for palliative care and hospice collaboration in the care of pediatric patients with end-stage renal disease. As chronic kidney disease progresses to end-stage renal disease (ESRD), important discussions regarding when and if to initiate dialysis occur. ESRD affects more than 660,000 Americans, less than 10,000 (1.5%) of those are pediatric patients whose time on dialysis is typically meant as a bridge to transplant. In rare circumstances, comorbidities, such as multiorgan failure, progression of other life-threating medical conditions, congenital anomalies, and size restrictions limit pediatric candidates’ access to transplant. In addition, dialysis-related infections and thrombosis can limit patients’ access to future transplant. Overall, this leads to a 5-year mortality for children with ESRD of 11%. Despite these mortality rates, very little has been published on pediatric palliative care (PPC) and hospice in ESRD. How can nephrology and PPC teams partner with each other, patients and caregivers to optimize care in pediatric ESRD? In this session, our multidisciplinary team will use recent cases, clinical literature, and Medicaid/Medicare regulations to inform attendees about shared challenges and solutions supporting patients with ESRD and their families. An overview of modes of renal replacement therapy, their limitations, and complications will be provided by pediatric nephrologists. Strategies to introduce the broad complement of PPC options and maintain open lines of communication between families and nephrology colleagues will be reviewed by PPC experts with experience caring for patients with ESRD. Finally, presenters will discuss challenges to implementing and maintaining palliative care principles, including those beyond end-of-life discussions, within the context of ESRD care. In this concurrent session, participants will have an opportunity to learn about ESRD care options and hear our centers’ experiences caring for these complex patients, highlighting the various roles of PPC, some challenges and ethical concerns we have encountered, and strategies to introduce palliative care within the pediatric ESRD population.

Why Pre-Curved Modiolar Hugging Electrodes Only Cover The Basal Turn of The Cochlea and Not Beyond that?

The question of why pre-curved modiolar hugging (MH) electrodes only cover the basal turn of the cochlea and not beyond that is unanswered yet in the CI field. Therefore the aim of this article is to show what the practical limitations are with the pre-curved MH electrode design in not being able to fabricate beyond one full turn. Every CI electrode design needs a metal mold with grooves for placing the platinum wires and for injecting with the silicone elastomer. Limitations in making a mold with groove that goes beyond one full turn of curvature along with the mechanical deformation of the curved silicone elastomer, prevents making a pre-curved MH electrode beyond one full turn. Electrode tip fold-over, electrode scalar deviation and the inconsistent electrode to modiolus wall proximity are the reported issues with this electrode type which does not help by any means to the operating surgeon and the pediatric candidates especially. If intra-operative imaging is recommended to confirm the proper placement of the electrode for one particular electrode design, then how many clinics in the world may have this facility and is it ethical to put the patient under more radiation risk are the natural questions that needs to be answered in the interest of the patient. Every CI brand should come out of their marketing philosophy and innovate what is essential in bringing the full benefit of the device to the patients.

Class I and II human leukocyte antibodies in pediatric haploidentical allograft candidates: prevalence and risk factors.

Donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) were associated with graft failure (GF) following haploidentical stem cell transplantation (Haplo-HSCT). The prevalence and risk factors of DSAs in pediatric candidates remain to be determined. In a prospective trial (ChiCTR-OPC-15006672), 486 children with hematological diseases were enrolled to screen for the presence of anti-HLA class I and II antibodies of immunoglobulin G type. Fifty two patients (10.7%) demonstrated positive panel-reactive antibody (PRA) for class I; 24 (4.9%), for class II; and 13 (2.7%), for both. Multivariate analysis showed diagnosis was the independent risk factor for antibodies, as acute lymphoblastic leukemia (ALL) patients (HR0.141, 95% CI: 0.037-0.538, p = 0.004) had a lower incidence of class II PRAs and DSAs against HLA-B, DQ, and DR, whereas myelodysplastic syndrome (MDS) patients had a higher incidence of PRAs for both class I and class II (HR4.790, 95% CI: 1.010-22.716, p = 0.049), and DSAs against HLA-A, B, C, DP, and DQ. Older age (>12 vs. ≤12) was associated with DSAs against HLA-DP (HR0.194, 95% CI: 0.041-0.918, p = 0.039). Our findings provided novel evidence for prevalence and risk factors for PRAs and DSAs in pediatric candidates receiving haplo-HSCT, possibly benefiting anti-HLA antibody monitoring and donor selection.

Imaging of Pediatric Hearing Loss.

Temporal bone high-resolution computed tomography (HRCT) and magnetic resonance (MR) imaging are valuable tools in the evaluation of pediatric hearing loss. Computed tomography is important in the evaluation of pediatric conductive hearing loss and is the imaging modality of choice for evaluation of osseous abnormalities. MR imaging is the modality of choice for evaluation of sensorineural hearing loss. A broad spectrum of imaging findings can be seen with hearing loss in children. HRCT and MR imaging provide complementary information and are often used in conjunction in the preoperative evaluation of pediatric candidates for cochlear implantation.

Donor organ turn-downs and outcomes after listing for pediatric heart transplant.

Pediatric heart transplant waitlist mortality remains significant but allograft offer refusals are common and allografts continue to be discarded. Our aim in this study was to assess the impact of donor organ refusals on mortality after listing using a multi-institutional data set. In this study we conducted a retrospective review of donor offers made to pediatric (<18 years) recipients in the United States in the period from 2007 to 2017. Candidates were stratified by whether they refused an acceptable donor offer (ADO). Acceptance was defined as an offer from a donor <40 years old and within 1,000 miles that was ultimately accepted by a waitlist candidate. Candidate survival after an offer was assessed. There were 12,447 hearts offered at least once to a pediatric candidate. Most candidates (n = 4,282, 84.4%) refused the first offer, and 677 (15.4%) of these subsequently died or were removed from the list for deterioration. Refusal of an ADO was associated with higher mortality after listing, independent of transplant, in both univariate (1 year: 92% vs 87%, p = 0.002) and multivariate (hazard ratio 1.5, 95% CI 1.2 to 1.7, p < 0.0001) Cox regression analyses. ADO refusals were not correlated with improved post-transplant survival and >8 ADO refusals was associated with higher risk-adjusted post-transplant mortality (odds ratio 1.7, 95% confidence interval 1.0 to 2.9, p = 0.04). Refusal of ADOs is associated with higher risk-adjusted mortality after listing (independent of transplantation), without improvement in post-transplant outcomes. So, although a "perfect" organ would be ideal, acceptance of one that is "good enough" has the potential to improve survival among pediatric candidates for heart transplantation.

Accuracy of the Pediatric End-stage Liver Disease Score in Estimating Pretransplant Mortality Among Pediatric Liver Transplant Candidates

Fair allocation of livers between pediatric and adult recipients is critically dependent on the accuracy of mortality estimates afforded by the Pediatric End-stage Liver Disease (PELD) and Model for End-stage Liver Disease, respectively. Widespread reliance on exceptions for pediatric recipients suggests that the 2 systems may not be comparable. To evaluate the accuracy of the PELD score in estimating 90-day pretransplant mortality among pediatric patients on the United Network for Organ Sharing (UNOS) waiting list. Patients who were listed from February 27, 2002, to March 31, 2014, for primary liver transplant were included in this retrospective analysis and were followed up for at least 2 years through June 17, 2016. The study analyzed 2 cohorts using the UNOS Standard Transplant Analysis and Research data files. The full cohort comprised 4298 patients (<18 years of age) who had chronic liver disease (excluding cancer). The reduced cohort (n = 2421) excluded patients receiving living donor transplantation or PELD exception points. Observed and expected 90-day pretransplant mortality rates evaluated at 10-point interval PELD levels. Among the 4298 patients in the full cohort (mean [SD] age, 2.5 [4.2] years; 2251 [52.4%] female; 2201 [51.2%] white), PELD scores and mortality were concordant (C statistic, 0.8387 [95% CI, 0.8191-0.8584] for the full cohort and 0.8123 [95% CI, 0.7919-0.8327] for the reduced cohort). However, the estimated 90-day mortality using the PELD score underestimated the actual probability of death by as much as 17%. With use of the PELD score, the ranking of risk among children was preserved, but direct comparisons between adult and pediatric candidates were not accurate. Children with chronic liver disease who are in need of transplant may be at a disadvantage compared with adults in a similar situation.

P151 Eliminating false positive flow cytometric crossmatches due to monoclonal antibody therapy

Aim Biologics are increasingly used in autoimmune, cancer, and transplant patients. Unfortunately they can also interfere in laboratory tests. Monoclonal antibodies, such as Rituximab, are well known to cause positive flow cytometry crossmatches (FCM) independent of donor specific HLA antibody (DSA). We assessed the ability of blocking antibodies to Rituximab (RTX) and Alemtuzumab (ALM) to negate interference by these biologics in the FCM. Methods FCM was performed with serum from patients receiving RTX and/or ALM. Some sera were pretreated with anti-Rituximab ( α RTX) and/or anti-Alemtuzumab ( α ALM) blocking antibodies (Bio-Rad, Inc). HLA DSA was determined using multiplex bead arrays (LabScreen Single Antigen, Thermofisher, Inc.). FCM channel shifts (CS) were compared between treated sera and sera treated with PBS as a control. Results Blocking antibodies were titrated in serum to determine the working dilution to use in subsequent studies. Sera from patients receiving RTX and/or ALM were treated with the predetermined dilution of blocking antibody. Blocking antibody pre-treatment reduced FCM CS with surrogate donors to levels comparable to PBS controls: RTX blocking: pre-treatment CS = 23 T and 302 B; post-treatment CS = 35 T and 29 B; ALM blocking: pre-treatment CS = 262 T and 236 B; post-treatment CS = 34 T and 2 B. A highly sensitized (cPRA = 99%; DSA ;= B35, Cw4, DR17, DR52, DQ5) pediatric renal transplant candidate (RTX and ALM treated) was crossmatched with their living donor using pre-transplant and 4 day post-transplant (post-RTX and ALM treatment) sera. Post-treatment CS were increased without blocking but reduced with blocking antibody treatment. Blocked FCM CS results correlated better with reduced DSA MFI summed values in contrast to the unblocked serum (Table 1). Conclusions Antibodies to RTX and ALM effectively block interference by these biologics in FCM resulting in the ability to provide useful FCM data for patient management.

Simultaneous Liver-Kidney Transplantation: Policy Update and the Challenges Ahead

Institution of a Simultaneous Liver Kidney (SLK) policy by the OPTN in 2016 represented the culmination of more than a decade of consensus conferences, public comments, and inter-society cooperation. The debates produced a multi-tiered proposal that established medical eligibility criteria for kidney allocation, a requirement for the regional sharing of a kidney to a MELD 35 medical eligible candidate and creation of a safety net for patients receiving a liver-alone transplant with subsequent kidney failure within the first post transplant year. The stratifications and alterations represented the first time that eligibility requirements have been instituted for allocating a multi-organ combination that is not tracked by the Scientific Registry of Transplant Recipients (SRTR). The provisions for reporting and follow-up of the allocation alteration have been identified and will be reported at regular intervals to the OPTN for public release. Although there are multiple interventions to limit the kidney utilization to those candidates with true medical necessity, it is unknown how this will impact the overall distribution of the kidneys, especially with the safety net now being offered to candidates that would not have met medical eligibility at the time of their transplant. As SLK comprises over 10% of all liver transplants, the requirement change may be significant and would hopefully result in the more efficient use of kidneys without a negative impact on patient survival. Although utilization would be much better monitored, the outcome measures would still be lacking. Even with this landmark change, review of the allocation process that presently favors allocating a kidney to a multi-organ transplant before allocation to a kidney-alone recipient is examined, especially as the prioritization affects pediatric candidates. It is hoped that advancements in this area would bring allocation policies into greater alignment with the intentions of the Final Rule legislation.

Pediatric Vascular Composite Allograft Transplantation: Medical Considerations

This report summarizes recent medical findings in the case of an allogenic bilateral hand-forearm allotransplantation in a previously immunocompromised child and discusses the implications for expanding vascular composite allotransplantation to non-immunocompromised pediatric candidates. A pediatric recipient of bilateral hand-forearm allotransplantation now over 2 years post-transplant has shown functional recovery that surpassed pre-transplant function, with evidence of somatosensory cortical reorganization. However, the child who was previously immunocompromised has required augmented immunosuppression and rehabilitation demands have been substantial. Pediatric vascular composite allotransplantation is surgically feasible, and short-term outcomes in the first case reveal the potential for functional benefits that exceed the pre-transplant state. Robust immunosuppression and its inherent risks must be clearly discussed with potential pediatric candidates and their families. Additionally, advanced planning for psychological and social support throughout the prolonged rehabilitation period is essential to optimize therapeutic engagement and academic learning.