Omicron Infections in Vaccinated Pediatric Solid Organ Transplant Recipients

SARS-CoV-2 infection during the Omicron period was frequent amongst a cohort of vaccinated pediatric solid organ transplant recipients (pSOTRs) despite robust anti-receptor-binding domain (anti-RBD) antibody response, suggesting poor neutralizing capacity against Omicron subvariants. Breakthrough infections among pSOTRs were overall limited in severity.

Anti-spike antibody durability after SARS-CoV-2 vaccination in adolescent solid organ transplant recipients

BACKGROUND

Adolescent solid organ transplant recipients (aSOTRs) who received three doses of the COVID-19 mRNA vaccine experience high seroconversion rates and antibody persistence for up to 3 months. Long-term antibody durability beyond this timeframe following three doses of the SARS-CoV-2 mRNA vaccine remains unknown. We describe antibody responses 6 months following the third vaccine dose (D3) of the BNT162b2 mRNA vaccination among aSOTRs.

METHODS

Participants in a multi-center, observational cohort who received the third dose of the vaccine were analyzed for antibodies to the SARS-CoV-2 spike protein receptor-binding domain (Roche Elecsys anti-SARS-CoV-2-S positive: ≥0.8, maximum: >2500 U/mL). Samples were collected at 1-, 3-, and 6-months post-D3. Participants were surveyed at each timepoint and at 12-months post-D3.

RESULTS

All 34 participants had positive anti-RBD antibody titers 6 months post-D3. Variations in titers occurred between 3 and 6 months post-D3, with 8/28 (29%) having decreased antibody levels at 6 months compared to 3 months and 2/28 (7%) reporting increased titers at 6 months. The remaining 18/28 (64%) had unchanged antibody titers compared to 3-month post-D3 levels. A total of 4/34 (12%) reported breakthrough infection within 6 months and 3/32 (9%) reported infection after 6-12 months following the third dose of the SARS-CoV-2 mRNA vaccine.

CONCLUSIONS

The results suggest that antibody durability persists up to 6 months following three doses of the SARS-CoV-2 mRNA in aSOTRs. Demography and transplant characteristics did not differ for those who experienced antibody weaning. Breakthrough infections did occur, reflecting immune-evasive nature of novel variants such as Omicron.

The unfinished journey toward transplant equity: an analysis of racial/ethnic disparities for children after the implementation of the Kidney Allocation System in 2014

BACKGROUND

Disparities in pediatric kidney transplantation (KT) result in reduced access and worse outcomes for minority children. We assessed the impact of recent systems changes on these disparities.

METHODS

This is a retrospective cohort study of pediatric patients utilizing data from the US Renal Data System (n = 7547) and Scientific Registry of Transplant Recipients (n = 6567 waitlisted and n = 6848 transplanted patients). We compared access to transplantation, time to deceased donor kidney transplant (DDKT), and allograft failure (ACGF) in the 5 years preceding implementation of the Kidney Allocation System (KAS) to the 5 years post-KAS implementation 2010-2014 vs. 2015-2019, respectively.

RESULTS

Compared to the pre-KAS era, post-KAS candidates were more likely to be pre-emptively listed (26.8% vs. 38.1%, p < 0.001), pre-emptively transplanted (23.8% vs. 28.0%, p < 0.001), and less likely to have private insurance (35.6% vs. 32.3%, p = 0.01), but these were not uniform across racial groups. Compared to white children, Black and Hispanic children had a lower likelihood of transplant listing within 2 years of first dialysis service (aHR 0.590.670.76 and 0.730.820.92, respectively) in the post-KAS era. Time to DDKT was comparable across all racial groups in the post-KAS era. Compared to white children, Black DDKT recipients have more 5-year ACGF (aHR 1.001.432.06 p = 0.05) while there was no difference in 3- or 5-year ACGF among LDKT recipients.

CONCLUSIONS

After KAS implementation, there is equity in time to DDKT. Pre-KAS increased hazard of ACGF among Black children has decreased in the post-KAS era; however, persistent disparities exist in time to transplant listing among Black and Hispanic children when compared to white children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Pediatric Kidney Transplantation-Can We Do Better? The Promise and Limitations of Epitope/Eplet Matching

Kidney transplant is the optimal treatment for end-stage kidney disease as it offers significant survival and quality of life advantages over dialysis. While recent advances have significantly improved early graft outcomes, long-term overall graft survival has remained largely unchanged for the last 20 years. Due to the young age at which children receive their first transplant, most children will require multiple transplants during their lifetime. Each subsequent transplant becomes more difficult because of the development of de novo donor specific HLA antibodies (dnDSA), thereby limiting the donor pool and increasing mortality and morbidity due to longer time on dialysis awaiting re-transplantation. Secondary prevention of dnDSA through increased post-transplant immunosuppression in children is constrained by a significant risk for viral and oncologic complications. There are currently no FDA-approved therapies that can meaningfully reduce dnDSA burden or improve long-term allograft outcomes. Therefore, primary prevention strategies aimed at reducing the risk of dnDSA formation would allow for the best possible long-term allograft outcomes without the adverse complications associated with over-immunosuppression. Epitope matching, which provides a more nuanced assessment of immunological compatibility between donor and recipient, offers the potential for improved donor selection. Although epitope matching is promising, it has not yet been readily applied in the clinical setting. Our review will describe current strengths and limitations of epitope matching software, the evidence for and against improved outcomes with epitope matching, discussion of eplet load vs. variable immunogenicity, and conclude with a discussion of the delicate balance of improving matching without disadvantaging certain populations.

Outcomes of SOT Recipients With COVID-19 in Different Eras of COVID-19 Therapeutics

BACKGROUND

Few reports have focused on newer coronavirus disease 2019 (COVID-19) therapies (remdesivir, dexamethasone, and convalescent plasma) in solid organ transplant recipients; concerns had been raised regarding possible adverse impact on allograft function or secondary infections.

METHODS

We studied 77 solid organ transplant inpatients with COVID-19 during 2 therapeutic eras (Era 1: March-May 2020, 21 patients; and Era 2: June-November 2020, 56 patients) and 52 solid organ transplant outpatients.

RESULTS

In Era 1, no patients received remdesivir or dexamethasone, and 4 of 21 (19.4%) received convalescent plasma, whereas in Era 2, remdesivir (24/56, 42.9%), dexamethasone (24/56, 42.9%), and convalescent plasma (40/56, 71.4%) were commonly used. Mortality was low across both eras, 4 of 77 (5.6%), and rejection occurred in only 2 of 77 (2.8%) inpatients; infections were similar in hypoxemic patients with or without dexamethasone. Preexisting graft dysfunction was associated with greater need for hospitalization, higher severity score, and lower survival. Acute kidney injury was present in 37.3% of inpatients; renal function improved more rapidly in patients who received remdesivir and convalescent plasma. Post-COVID-19 renal and liver function were comparable between eras, out to 90 d.

CONCLUSIONS

Newer COVID-19 therapies did not appear to have a deleterious effect on allograft function, and infectious complications were comparable.

Eplet mismatches associated with de novo donor-specific HLA antibody in pediatric kidney transplant recipients

BACKGROUND

Optimizing amino acid (eplet) histocompatibility at first transplant decreases the risk of de novo donor-specific antibody (dnDSA) development and may improve long-term graft survival in pediatric kidney transplant recipients (KTR). We performed a retrospective analysis of pediatric KTR and their respective donors to identify eplets most commonly associated with dnDSA formation.

METHODS

Eplet mismatch analysis was performed in a cohort of 125 pediatric KTR-donor pairs (2006-2018). We determined the prevalence of each eplet mismatch and quantified the percentage of exposed patients who developed dnDSA for each mismatched eplet.

RESULTS

Recipient median age was 14 (IQR 8-17) years with a racial distribution of 42% Black, 48% Caucasian, and 5.6% Middle-Eastern. Median eplet load varied significantly by recipient race, Black 82 (IQR 58-98), White 60 (IQR 44-81) and Other 66 (IQR 61-76), p = 0.002. Forty-four percent of patients developed dnDSA after median 37.1 months. Compared to dnDSA- patients, dnDSA+ patients had higher median eplet load, 64 (IQR 46-83) vs. 77 (IQR 56-98), p = 0.012. The most common target of dnDSA were eplets expressed in HLA-A*11 and A2 in Class I, and HLA-DQ6 and DQA5 in Class II. The most commonly mismatched eplets were not the most likely to result in dnDSA formation.

CONCLUSIONS

In a racially diverse population, only a subset of eplets was linked to antibody formation. Eplet load alone is not a sufficient surrogate for eplet immunogenicity. These findings illustrate the need to optimize precision in donor selection and allocation to improve long-term graft outcomes. Graphical Abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

Promoting cardiovascular health post-transplant through early diagnosis and adequate management of hypertension and dyslipidemia

Despite correction of underlying solid organ failure by transplantation, pediatric transplant recipients still have increased mortality rates compared to the general pediatric population, in part due to increased cardiovascular risk. In particular, pediatric kidney and non-kidney transplant recipients with chronic kidney disease have significant cardiovascular risk that worsens with declining kidney function. Biomarkers associated with future cardiovascular risk such as casual and ambulatory hypertension, dyslipidemia, vascular stiffness and calcification, and left ventricular hypertrophy can be detected throughout the post-transplant period and in patients with stable kidney function. Among these, hypertension and dyslipidemia are two potentially modifiable cardiovascular risk factors that are highly prevalent in kidney and non-kidney pediatric transplant recipients. Standardized approaches to appropriate BP measurement and lipid monitoring are needed to detect and address these risk factors in a timely fashion. To achieve sustained improvement in cardiovascular health, clinicians should partner with patients and their caregivers to address these and other risk factors with a combined approach that integrates pharmacologic with non-pharmacologic approaches. This review outlines the scope and impact of hypertension and dyslipidemia in pediatric transplant recipients, with a particular focus on pediatric kidney transplantation given the high burden of chronic kidney disease-associated cardiovascular risk. We also review the current published guidelines for monitoring and managing abnormalities in blood pressure and lipids, highlighting the important role of therapeutic lifestyle changes in concert with antihypertensive and lipid-lowering medications.

Effects of COVID-19 pandemic on pediatric kidney transplant in the United States

BACKGROUND

In March 2020, COVID-19 infections began to rise exponentially in the USA, placing substantial burden on the healthcare system. As a result, there was a rapid change in transplant practices and policies, with cessation of most procedures. Our goal was to understand changes to pediatric kidney transplantation (KT) at the national level during the COVID-19 epidemic.

METHODS

Using SRTR data, we examined changes in pediatric waitlist registration, waitlist removal or inactivation, and deceased donor and living donor (DDKT/LDKT) events during the start of the disease transmission in the USA compared with the same time the previous year.

RESULTS

We saw an initial decrease in DDKT and LDKT by 47% and 82% compared with expected events and then a continual increase, with numbers reaching expected prepandemic levels by May 2020. In the early phase of the pandemic, waitlist inactivation and removals due to death or deteriorating condition rose above expected values by 152% and 189%, respectively. There was a statistically significant decrease in new waitlist additions (IRR _0.49 0.65 _0.85) and LDKT (IRR _0.17 0.38 _0.84) in states with high vs. low COVID activity. Transplant recipients during the pandemic were more likely to have received a DDKT, but had similar calculated panel-reactive antibody (cPRA) values, waitlist time, and cause of kidney failure as before the pandemic.

CONCLUSIONS

The COVID-19 pandemic initially reduced access to kidney transplantation among pediatric patients in the USA but has not had a sustained effect.

Effects of COVID19 Pandemic on Pediatric Kidney Transplant in the United States

In March 2020, COVID-19 infections began to rise exponentially in the United States, placing substantial burden on the healthcare system. As a result, there was a rapid change in transplant practices and policies, with cessation of most procedures. Our goal was to understand changes to pediatric kidney transplantation (KT) at the national level during the COVID-19 epidemic. Using SRTR data, we examined changes in pediatric waitlist registration, waitlist removal or inactivation, and deceased donor and living donor (DDKT/LDKT) events during the start of the disease transmission in the United States compared to the same time the previous year. We saw an initial decrease in DDKT and LDKT by 47% and 82% compared to expected events and then a continual increase, with numbers reaching expected pre-pandemic levels by May 2020. In the early phase of the pandemic, waitlist inactivation and removals due to death or deteriorating condition rose above expected values by 152% and 189%, respectively. There was a statistically significant decrease in new waitlist additions (IRR _0.49 0.65 _0.85) and LDKT (IRR _0.17 0.38 _0.84) in states with high vs low COVID activity. Transplant recipients during the pandemic were more likely to have received a DDKT, but had similar cPRA, waitlist time and cause of ESRD as before the pandemic. The COVID-19 pandemic initially reduced access to kidney transplantation among pediatric patients in the United States, but has not had a sustained effect.

Changes in offer and acceptance patterns for pediatric kidney transplant candidates under the new Kidney Allocation System

Stakeholders have expressed concerns regarding decreased deceased donor kidney transplant (DDKT) rates for pediatric candidates under the Kidney Allocation System (KAS). To better understand what might be driving this, we studied Scientific Registry of Transplant Recipients kidney offer data for 3642 pediatric (age <18 years) kidney-only transplant candidates between December 31, 2012 to December 3, 2014 (pre-KAS) and December 4, 2014 to January 6, 2017 (post-KAS). We used negative binomial regression and multilevel logistic regression to compare offer and acceptance rates pre- and post-KAS. We stratified by donor age (<18, 18-34, and 35+ years) and KDPI (<35% and ≥35%) to reflect differing allocation prioritization pre-KAS and post-KAS. As might be expected from prioritization changes, post-KAS candidates were less likely to receive offers for donors 18-34 years old with KDPI ≥ 35% (adjusted incidence rate ratio [aIRR]: 0.18 0.210.25 , P < .001), and more likely to receive offers for donors 18-34 years old and KDPI < 35% (aIRR: 1.12 1.201.29 , P < .001). However, offer acceptance practices also changed post-KAS: kidneys from donors 18-34 years old and KDPI < 35% were 23% less likely to be accepted post-KAS (adjusted odds ratio: 0.61 0.770.98 , P = .03). Using kidneys from donors 18-34 years old with KDPI < 35% post-KAS to the same extent they were used pre-KAS might be an effective strategy to mitigate any decrease in DDKT rates for pediatric candidates.

Access to Transplantation for Undocumented Pediatric Patients

Clinicians in the United States today regularly face dilemmas about health disparities. Many patients and families cannot afford the medical care that doctors recommend. These problems are most stark when the medical care that is needed is lifesaving and expensive and involves scarce resources. Transplants are the best example of this. The most ethically disturbing situations occur when an undocumented immigrant child needs a transplant. We present such a case and analyze the ethical, legal, and policy issues that arise.

Eplet mismatch analysis and allograft outcome across racially diverse groups in a pediatric transplant cohort: a single-center analysis

HLA eplet mismatch load has been suggested as an improvement to HLA antigen mismatch determination for organ selection. Given that eplet mismatches are determined based on amino acid sequence difference among HLA alleles, and that the frequency of HLA alleles varies between racial groups, we investigated the correlation between eplet mismatch load and allograft outcomes in 110 pediatric kidney transplant recipients who received their first organ from a donor of the same race (SRT) versus a donor of a different race (DRT). Adjusted modified Poisson regression was used to assess the interaction between eplet mismatch load and race mismatch and its effect on outcome. Caucasians and living donor recipients had lower eplet mismatched loads against their donors compared with non-Caucasian and deceased donor recipients. Overall, for the entire population, the risk of de novo HLA-DSA development was significantly increased with higher eplet loads (p < 0.001). Compared with the SRT group, the DRT group had higher eplet loads when compared with their donor, for HLA class I but not HLA class II molecules; however, there was no significant difference in the incidence of de novo HLA-DSA between the 2 groups. The risk of rejection increased significantly for DRT compared with SRT, only when class I eplet load was ≥ 70 (p = 0.04). Together this data show that eplet mismatch load analysis is an effective tool for alloimmune risk assessment. If considered for donor selection, acceptable eplet mismatch loads determined from studies in homogenous populations may restrict transplantation across racially diverse donor and patient groups with no evidence of poor outcome. Therefore, an acceptable eplet mismatch load threshold must consider the heterogeneity of the transplant population.

Correction to: Eplet mismatch analysis and allograft outcome across racially diverse groups in a pediatric transplant cohort: a single-center analysis

The original version of this article unfortunately contained a mistake. In the third paragraph of "Discussion," two references were missing.

The prevalence and outcome of children with failure to thrive after pediatric kidney transplantation

BACKGROUND

Prior to transplantation, effects of advanced CKD contribute to malnutrition and impaired growth. After transplant, children are expected to thrive, however, in a subset of transplant recipients this does not occur. Factors associated with post-transplant FTT are poorly understood.

OBJECTIVE

A retrospective cohort study was conducted to determine factors associated with FTT and association of FTT with infections and hospitalizations.

METHODS

Records of 119 children transplanted between 2005 and 2016 were reviewed. FTT was defined by ≥2 of the following post-transplant criteria: (a) low BMI or deceleration in BMI z-score, (b) poor growth velocity, and (c) chronic hypoalbuminemia at 1 or 3 years post-transplant. Association of FTT with deceased donor transplant, de novo DSA, intolerance to MMF, anemia, vitamin D deficiency, and CIC was investigated by logistic regression. Poisson regression was used to identify outcomes associated with FTT.

RESULTS

Low pre-transplant BMI and post-transplant CIC dependence were independently associated with FTT after transplant. Odds of FTT at 1 year post-transplant decreased by 0.5 for each 1 unit increase in pre-transplant BMI z-score. Requirement for CIC conferred 3.8 and 7.8 higher odds of FTT at 1 and 3 years. Patients with FTT had 2.7 and 2.6 times infections and hospitalizations during the first year, and 4.2 and 4.3 times infections and hospitalizations over 3 years post-transplant.

CONCLUSIONS

Children with low BMI prior to transplant and those requiring CIC after transplant are at increased risk for post-transplant FTT. FTT is associated with adverse outcomes, evidenced by increased infections and hospitalizations.

Quality Improvement Initiative to Reduce Admissions for Nephrotic Syndrome Relapse in Pediatric Patients

Introduction: Childhood nephrotic syndrome is frequently seen in pediatric nephrology practice and often requires patient hospitalization for management. Numerous complications of this disease can be managed in an outpatient setting if brought to the attention of the medical team in a timely manner. Outpatient management will reduce healthcare cost and improve patient safety. The goal of this quality improvement initiative was to reduce admissions for nephrotic syndrome relapse from 8 to <5 admissions at a single center in a 3-month period. Methods: Fish-bone analysis was used to determine barriers to early recognition of relapse and successful outpatient care. Patient education about the disease process was identified as the primary barrier. A standardized approach to patient education as well as educational materials were developed. Champions were identified within each stakeholder group to train and disseminate the new process. Admission counts were compared from 3 years prior to implementation to 2 years post-implementation. Clinic visits for nephrotic syndrome were tallied as a balancing measure. Patients were surveyed in the outpatient clinics about whether they had ever received the education as a process measure. Results: Admission counts were reduced and met goal for the first 3 quarters that were examined; however, the number of admissions went above target in the last quarter. Clinic visit numbers did not change over the study period. Process measure showed that 75-80% of families were provided with nephrotic syndrome education. Conclusion: A standardized approach to patient and family education about idiopathic nephrotic syndrome can reduce admissions for management of relapse. This will reduce healthcare expenditure as well as improve patient safety.

Results of early treatment for de novo donor-specific antibodies in pediatric kidney transplant recipients in a cross-sectional and longitudinal cohort

The development of dnDSA anti-HLA antibodies has been shown to be a significant risk factor for graft failure. In 2008, we instituted a routine protocol of standardized monitoring and treatment of dnDSA in pediatric kidney transplant recipients. Of 67 first-time pediatric kidney transplant recipients, 26 (38%) developed dnDSA after 1.36 (IQ 1-2.14) years. Coefficient of variance of tacrolimus, a surrogate marker of non-adherence, was found to be the single most important risk factor for dnDSA development. Overall, there was a significant reduction in dnDSA with treatment in 19 (76%) children. No difference in graft survival and estimated glomerular filtration rate was noted between dnDSA negative and those treated for dnDSA. There was an increased risk of hospitalization in those treated for dnDSA. This study suggests that early detection and treatment of dnDSA can help to prevent graft failure and preserve graft function in the short term. Future studies and longer follow-up are needed to fully elucidate the effect of early detection and treatment of dnDSA in pediatric kidney transplant recipients.

Hypertension in the Pediatric Kidney Transplant Recipient

Hypertension after kidney transplant is a frequent occurrence in pediatric patients. It is a risk factor for graft loss and contributes to the significant burden of cardiovascular disease (CVD) in this population. The etiology of posttransplant hypertension is multifactorial including donor factors, recipient factors, medications, and lifestyle factors similar to those prevalent in the general population. Ambulatory blood pressure monitoring has emerged as the most reliable method for measuring hypertension in pediatric transplant recipients, and many consider it to be essential in the care of these patients. Recent technological advances including measurement of carotid intima-media thickness, pulse wave velocity, and myocardial strain using specked echocardiography and cardiac magnetic resonance imaging have improved our ability to assess CVD burden. Since hypertension remains underrecognized and inadequately treated, an early diagnosis and an appropriate control should be the focus of therapy to help improve patient and graft survival.