National study on the risks of COVID-19 infection for paediatric kidney transplant recipients: a retrospective, cross-sectional study.

INTRODUCTION: During the COVID-19 pandemic, evidence emerged that immunosuppressed children were less affected by COVID-19 infections compared with immunosuppressed adults. The aim of our study was to investigate how COVID-19 infections affected paediatric kidney transplant recipients (pKTR) in the UK. METHODS: Questionnaires regarding COVID-19 infection data and care of pKTR during the COVID-19 pandemic were sent to all 13 UK paediatric nephrology centres examining asymptomatic and symptomatic pKTR with positive COVID-19 PCR testing from 1 April 2020 to 1 December 2021. RESULTS: 63 pKTR who were 3.1 (range 0.1-15) years post-transplantation had COVID-19 infection with positive SARS-CoV-2 PCR RNA. Classical COVID-19 symptoms were present in half of the patients; with atypical presentations including diarrhoea (13%) and lethargy (13%) also noted, while a third of patients were asymptomatic. Eighteen patients (28%) were hospitalised including five asymptomatic patients admitted for other reasons. No patients needed ventilation or intensive care admission, and one patient received supplemental oxygen. There was evidence of acute kidney injury (AKI) in 71% of patients, but no patients needed kidney replacement therapy with haemofiltration or dialysis. CONCLUSION: We report 10.4% of the UK paediatric renal transplantation population had documented COVID-19 infections with positive SARS-CoV-2 PCR RNA with 28% of those affected requiring hospitalisation. The increased incidence of AKI, particularly after the first wave of the COVID-19 pandemic, was possibly due to increased testing. There was low morbidity and mortality compared with the adult population.

Advanced chronic kidney disease among UK children.

The UK Renal Registry currently collects information on UK children with kidney failure requiring long-term kidney replacement therapy (KRT), which supports disease surveillance and auditing of care and outcomes; however, data are limited on children with chronic kidney disease (CKD) not on KRT. METHODS: In March 2020, all UK Paediatric Nephrology centres submitted data on children aged <16 years with severely reduced kidney function as of December 2019, defined as an estimated glomerular filtration rate <30 mL/min/1.73 m2. RESULTS: In total, 1031 children had severe CKD, the majority of whom (80.7%) were on KRT. The overall prevalence was 81.2 (95% CI 76.3 to 86.3) per million of the age-related population. CONCLUSIONS: The prevalence of severe CKD among UK children is largely due to a high proportion of children on long-term KRT. Expanding data capture to include children with CKD before reaching failure will provide greater understanding of the CKD burden in childhood.

Economic Evaluation of Using Daily Prednisolone versus Placebo at the Time of an Upper Respiratory Tract Infection for the Management of Children with Steroid-Sensitive Nephrotic Syndrome: A Model-Based Analysis.

BACKGROUND: Childhood steroid-sensitive nephrotic syndrome is a frequently relapsing disease with significant short- and long-term complications, leading to high healthcare costs and reduced quality of life for patients. The majority of relapses are triggered by upper respiratory tract infections (URTIs) and evidence shows that daily low-dose prednisolone at the time of infection may reduce the risk of relapse. OBJECTIVE: The aim of this study was to assess the cost effectiveness of a 6-day course of low-dose prednisolone at the start of a URTI when compared with placebo. METHODS: A state-transition Markov model was developed to conduct a cost-utility analysis with the outcome measured in quality-adjusted life-years (QALYs). Resource use and outcome data were derived from the PREDNOS2 trial. The analysis was performed from a UK National Health Service perspective and the results were extrapolated to adulthood. Model parameter and structural uncertainty were assessed using sensitivity analyses. RESULTS: The base-case results showed that administering low-dose prednisolone at the time of a URTI generated more QALYs and a lower mean cost at 1 year compared with placebo. In the long-term, low-dose prednisolone was associated with a cost saving (£176) and increased effectiveness (0.01 QALYs) compared with placebo and thus remained the dominant treatment option. These findings were robust to all sensitivity analyses. CONCLUSION: A 6-day course of low-dose prednisolone at the time of a URTI in children with steroid-sensitive nephrotic syndrome has the potential to reduce healthcare costs and improve quality of life compared with placebo.

Exploring the relevance of NUP93 variants in steroid-resistant nephrotic syndrome using next generation sequencing and a fly kidney model.

BACKGROUND: Variants in genes encoding nuclear pore complex (NPC) proteins are a newly identified cause of paediatric steroid-resistant nephrotic syndrome (SRNS). Recent reports describing NUP93 variants suggest these could be a significant cause of paediatric onset SRNS. We report NUP93 cases in the UK and demonstrate in vivo functional effects of Nup93 depletion in a fly (Drosophila melanogaster) nephrocyte model. METHODS: Three hundred thirty-seven paediatric SRNS patients from the National cohort of patients with Nephrotic Syndrome (NephroS) were whole exome and/or whole genome sequenced. Patients were screened for over 70 genes known to be associated with Nephrotic Syndrome (NS). D. melanogaster Nup93 knockdown was achieved by RNA interference using nephrocyte-restricted drivers. RESULTS: Six novel homozygous and compound heterozygous NUP93 variants were detected in 3 sporadic and 2 familial paediatric onset SRNS characterised histologically by focal segmental glomerulosclerosis (FSGS) and progressing to kidney failure by 12 months from clinical diagnosis. Silencing of the two orthologs of human NUP93 expressed in D. melanogaster, Nup93-1, and Nup93-2 resulted in significant signal reduction of up to 82% in adult pericardial nephrocytes with concomitant disruption of NPC protein expression. Additionally, nephrocyte morphology was highly abnormal in Nup93-1 and Nup93-2 silenced flies surviving to adulthood. CONCLUSION: We expand the spectrum of NUP93 variants detected in paediatric onset SRNS and demonstrate its incidence within a national cohort. Silencing of either D. melanogaster Nup93 ortholog caused a severe nephrocyte phenotype, signaling an important role for the nucleoporin complex in podocyte biology. A higher resolution version of the Graphical abstract is available as Supplementary information.

Daily low-dose prednisolone to prevent relapse of steroid-sensitive nephrotic syndrome in children with an upper respiratory tract infection: PREDNOS2 RCT.

BACKGROUND: Most children with steroid-sensitive nephrotic syndrome have relapses that are triggered by upper respiratory tract infections. Four small trials, mostly in children already taking maintenance corticosteroid in countries of different upper respiratory tract infection epidemiology, showed that giving daily low-dose prednisone/prednisolone for 5-7 days during an upper respiratory tract infection reduces the risk of relapse. OBJECTIVES: To determine if these findings were replicated in a large UK population of children with relapsing steroid-sensitive nephrotic syndrome on different background medication or none. DESIGN: A randomised double-blind placebo-controlled trial, including a cost-effectiveness analysis. SETTING: A total of 122 UK paediatric departments, of which 91 recruited patients. PARTICIPANTS: A total of 365 children with relapsing steroid-sensitive nephrotic syndrome (mean age 7.6 ± 3.5 years) were randomised (1 : 1) according to a minimisation algorithm based on background treatment. Eighty children completed 12 months of follow-up without an upper respiratory tract infection. Thirty-two children were withdrawn from the trial (14 prior to an upper respiratory tract infection), leaving a modified intention-to-treat analysis population of 271 children (134 and 137 children in the prednisolone and placebo arms, respectively). INTERVENTIONS: At the start of an upper respiratory tract infection, children received 6 days of prednisolone (15 mg/m2) or an equivalent dose of placebo. MAIN OUTCOME MEASURES: The primary outcome was the incidence of first upper respiratory tract infection-related relapse following any upper respiratory tract infection over 12 months. The secondary outcomes were the overall rate of relapse, changes in background treatment, cumulative dose of prednisolone, rates of serious adverse events, incidence of corticosteroid adverse effects, change in Achenbach Child Behaviour Checklist score and quality of life. Analysis was by intention-to-treat principle. The cost-effectiveness analysis used trial data and a decision-analytic model to estimate quality-adjusted life-years and costs at 1 year, which were then extrapolated over 16 years. RESULTS: There were 384 upper respiratory tract infections and 82 upper respiratory tract infection-related relapses in the prednisolone arm, and 407 upper respiratory tract infections and 82 upper respiratory tract infection-related relapses in the placebo arm. The number of patients experiencing an upper respiratory tract infection-related relapse was 56 (42.7%) and 58 (44.3%) in the prednisolone and placebo arms, respectively (adjusted risk difference -0.024, 95% confidence interval -0.14 to 0.09; p = 0.70). There was no evidence that the treatment effect differed when data were analysed according to background treatment. There were no significant differences in secondary outcomes between treatment arms. Giving daily prednisolone at the time of an upper respiratory tract infection was associated with increased quality-adjusted life-years (0.9427 vs. 0.9424) and decreased average costs (£252 vs. £254), when compared with standard care. The cost saving was driven by background therapy and hospitalisations after relapse. The finding was robust to sensitivity analysis. LIMITATIONS: A larger number of children than expected did not have an upper respiratory tract infection and the sample size attrition rate was adjusted accordingly during the trial. CONCLUSIONS: The clinical analysis indicated that giving 6 days of daily low-dose prednisolone at the time of an upper respiratory tract infection does not reduce the risk of relapse of steroid-sensitive nephrotic syndrome in UK children. However, there was an economic benefit from costs associated with background therapy and relapse, and the health-related quality-of-life impact of having a relapse. FUTURE WORK: Further work is needed to investigate the clinical and health economic impact of relapses, interethnic differences in treatment response, the effect of different corticosteroid regimens in treating relapses, and the pathogenesis of individual viral infections and their effect on steroid-sensitive nephrotic syndrome. TRIAL REGISTRATION: Current Controlled Trials ISRCTN10900733 and EudraCT 2012-003476-39. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 3. See the NIHR Journals Library website for further project information.

Steroid-sensitive nephrotic syndrome is a kidney condition in which protein leaks into the urine, causing generalised swelling. In most children, the condition recurs or relapses. Relapses often occur following an upper respiratory tract infection (i.e. a cough, cold or sore throat). Research in tropical countries suggests that if children have a small dose of daily steroids for a week at the time of an upper respiratory tract infection then they are less likely to relapse. The selection of children for these studies and the different patterns of infection mean that we are not certain if this treatment would work in the UK. A total of 365 children with relapsing nephrotic syndrome took part. Half of the children took a steroid and the other half took dummy tablets (placebo) for 6 days at the start of an upper respiratory tract infection. We followed up the children for 12 months and collected information on relapses and other treatments and information from questionnaires about behaviour and quality of life. We also investigated whether or not there were cost savings with this treatment. There were 271 children who had an upper respiratory tract infection in the 12 months of the study and so only these children were included in the analyses. Giving 6 days of a low-dose steroid at the time of an upper respiratory tract infection did not reduce the risk of a relapse. There was also no effect on the overall number of relapses, the number of children needing to start extra preventative treatments or side effects of steroids. Although there was no clinical effect, the economic evaluation found that giving prednisolone led to lower treatment costs overall and higher quality of life and might, therefore, offer better value for money, but this has to be interpreted against the clinical evidence of no significant effect. Our conclusion is that there is no clinical benefit to giving children low-dose prednisolone at the time of an upper respiratory tract infection.

Evaluation of Daily Low-Dose Prednisolone During Upper Respiratory Tract Infection to Prevent Relapse in Children With Relapsing Steroid-Sensitive Nephrotic Syndrome: The PREDNOS 2 Randomized Clinical Trial.

IMPORTANCE: In children with corticosteroid-sensitive nephrotic syndrome, many relapses are triggered by upper respiratory tract infections. Four small studies found that administration of daily low-dose prednisolone for 5 to 7 days at the time of an upper respiratory tract infection reduced the risk of relapse, but the generalizability of their findings is limited by location of the studies and selection of study population. OBJECTIVE: To investigate the use of daily low-dose prednisolone for the treatment of upper respiratory tract infection-related relapses. DESIGN, SETTING, AND PARTICIPANTS: This double-blind, placebo-controlled randomized clinical trial (Prednisolone in Nephrotic Syndrome [PREDNOS] 2) evaluated 365 children with relapsing steroid-sensitive nephrotic syndrome with and without background immunosuppressive treatment at 122 pediatric departments in the UK from February 1, 2013, to January 31, 2020. Data from the modified intention-to-treat population were analyzed from July 1, 2020, to December 31, 2020. INTERVENTIONS: At the start of an upper respiratory tract infection, children received 6 days of prednisolone, 15 mg/m2 daily, or matching placebo preparation. Those already taking alternate-day prednisolone rounded their daily dose using trial medication to the equivalent of 15 mg/m2 daily or their alternate-day dose, whichever was greater. MAIN OUTCOMES AND MEASURES: The primary outcome was the incidence of first upper respiratory tract infection-related relapse. Secondary outcomes included overall rate of relapse, changes in background immunosuppressive treatment, cumulative dose of prednisolone, rates of serious adverse events, incidence of corticosteroid adverse effects, and quality of life. RESULTS: The modified intention-to-treat analysis population comprised 271 children (mean [SD] age, 7.6 [3.5] years; 174 [64.2%] male), with 134 in the prednisolone arm and 137 in the placebo arm. The number of patients experiencing an upper respiratory tract infection-related relapse was 56 of 131 (42.7%) in the prednisolone arm and 58 of 131 (44.3%) in the placebo arm (adjusted risk difference, -0.02; 95% CI, -0.14 to 0.10; P = .70). No evidence was found that the treatment effect differed according to background immunosuppressive treatment. No significant differences were found in secondary outcomes between the treatment arms. A post hoc subgroup analysis assessing the primary outcome in 54 children of South Asian ethnicity (risk ratio, 0.66; 95% CI, 0.40-1.10) vs 208 children of other ethnicity (risk ratio, 1.11; 95% CI, 0.81-1.54) found no difference in efficacy of intervention in those of South Asian ethnicity (test for interaction P = .09). CONCLUSIONS AND RELEVANCE: The results of PREDNOS 2 suggest that administering 6 days of daily low-dose prednisolone at the time of an upper respiratory tract infection does not reduce the risk of relapse of nephrotic syndrome in children in the UK. Further work is needed to investigate interethnic differences in treatment response. TRIAL REGISTRATION: isrctn.org Identifier: ISRCTN10900733; EudraCT 2012-003476-39.

Focal segmental glomerulosclerosis and mild intellectual disability in a patient with a novel de novo truncating TRIM8 mutation.

Mutations in the TRIM8 gene have been described in patients with severe developmental delay, intellectual disability and epilepsy. Only six patients have been described to date. All the previous mutations were truncating variants clustered in the C-terminus of the protein. A previous patient with TRIM8-related epileptic encephalopathy was reported to have nephrotic syndrome. Here we describe the clinical, radiological and histological features of an 8-year-old male patient with a TRIM8 mutation who, in contrast to previous patients, had only mild intellectual disability and well-controlled epilepsy. The patient was found to have proteinuria at 2 years of age. Renal biopsy findings were suggestive of focal segmental glomerulosclerosis. His kidney function declined and peritoneal dialysis was started at 5 years of age. He underwent renal transplant at 7 years of age. Trio-based whole genome sequencing identified a novel de novo heterozygous frameshift mutation in TRIM8 (NM_030912.2) c.1198_1220del, p.(Tyr400ArgfsTer2). This patient is further evidence that TRIM8 mutations cause a syndrome with both neurological and renal features. Our findings suggest the spectrum of TRIM8-related disease may be wider than previously thought with the possibility of milder neurodevelopmental problems and/or a more severe, progressive renal phenotype. We highlight the need for proteinuria screening in patients with TRIM8 mutations.

Factor H autoantibody is associated with atypical hemolytic uremic syndrome in children in the United Kingdom and Ireland.

Factor H autoantibodies can impair complement regulation, resulting in atypical hemolytic uremic syndrome, predominantly in childhood. There are no trials investigating treatment, and clinical practice is only informed by retrospective cohort analysis. Here we examined 175 children presenting with atypical hemolytic uremic syndrome in the United Kingdom and Ireland for factor H autoantibodies that included 17 children with titers above the international standard. Of the 17, seven had a concomitant rare genetic variant in a gene encoding a complement pathway component or regulator. Two children received supportive treatment; both developed established renal failure. Plasma exchange was associated with a poor rate of renal recovery in seven of 11 treated. Six patients treated with eculizumab recovered renal function. Contrary to global practice, immunosuppressive therapy to prevent relapse in plasma exchange-treated patients was not adopted due to concerns over treatment-associated complications. Without immunosuppression, the relapse rate was high (five of seven). However, reintroduction of treatment resulted in recovery of renal function. All patients treated with eculizumab achieved sustained remission. Five patients received renal transplants without specific factor H autoantibody-targeted treatment with recurrence in one who also had a functionally significant CFI mutation. Thus, our current practice is to initiate eculizumab therapy for treatment of factor H autoantibody-mediated atypical hemolytic uremic syndrome rather than plasma exchange with or without immunosuppression. Based on this retrospective analysis we see no suggestion of inferior treatment, albeit the strength of our conclusions is limited by the small sample size.

Simultaneous sequencing of 24 genes associated with steroid-resistant nephrotic syndrome.

BACKGROUND AND OBJECTIVES: Up to 95% of children presenting with steroid-resistant nephrotic syndrome in early life will have a pathogenic single-gene mutation in 1 of 24 genes currently associated with this disease. Others may be affected by polymorphic variants. There is currently no accepted diagnostic algorithm for clinical genetic testing. The hypothesis was that the increasing reliability of next generation sequencing allows comprehensive one-step genetic investigation of this group and similar patient groups. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study used next generation sequencing to screen 446 genes, including the 24 genes known to be associated with hereditary steroid-resistant nephrotic syndrome. The first 36 pediatric patients collected through a national United Kingdom Renal Registry were chosen with comprehensive phenotypic detail. Significant variants detected by next generation sequencing were confirmed by conventional Sanger sequencing. RESULTS: Analysis revealed known and novel disease-associated variations in expected genes such as NPHS1, NPHS2, and PLCe1 in 19% of patients. Phenotypically unexpected mutations were also detected in COQ2 and COL4A4 in two patients with isolated nephropathy and associated sensorineural deafness, respectively. The presence of an additional heterozygous polymorphism in WT1 in a patient with NPHS1 mutation was associated with earlier-onset disease, supporting modification of phenotype through genetic epistasis. CONCLUSIONS: This study shows that next generation sequencing analysis of pediatric steroid-resistant nephrotic syndrome patients is accurate and revealing. This analysis should be considered part of the routine genetic workup of diseases such as childhood steroid-resistant nephrotic syndrome, where the chance of genetic mutation is high but requires sequencing of multiple genes.

HIV-associated nephropathy in the setting of maximal virologic suppression.

Human immunodeficiency virus (HIV)-associated nephropathy (HIVAN) is most frequently seen as a late manifestation in adult patients with a high viral load and low T-helper cell (CD4) counts. We report a case of HIVAN in a black Zimbabwean teenager in whom the disease activity was well suppressed for years following highly active antiretroviral therapy (HAART). Proteinuria was absent at 9 years of age when he presented with vertically transmitted HIV infection. Within a few months of HAART, the viral load became undetectable and CD4 count was normalised. Nephrotic range proteinuria, with preserved renal function, developed approximately 4 years later despite excellent HIV disease suppression. Renal biopsy showed non-collapsing focal segmental glomerular sclerosis changes compatible with HIVAN. Although the role of other unknown factors in the disease pathogenesis could not be totally excluded, this case demonstrates that HIVAN can still occur in HIV-infected children despite excellent HAART and that the disease manifestations and outcome may differ from those reported in previous studies.

Renal agenesis and unilateral nephrectomy: what are the risks of living with a single kidney?

The long-term outlook for patients with unilateral renal agenesis or following unilateral nephrectomy in childhood is controversial. Animal studies suggest that the resultant compensatory increase in glomerular filtration might lead to progressive damage to the remaining renal tissue and may generate hypertension. Human studies addressing these concerns are limited in number and are difficult to interpret because they are small, retrospective, or cross sectional with significant variations in duration and completeness of follow-up. The published studies suggest that renal function remains stable for several decades in the majority of subjects. The clinical significance of mild-grade proteinuria and hypertension seen in some patients is unknown. Longitudinal studies are needed to understand the long-term effect and significance of the several pathophysiological changes observed in the solitary kidney.

Follow-up of early unilateral nephrectomy for hypertension.

Early unilateral nephrectomy was carried out in four young children with unilateral renovascular disease, a poorly functioning kidney and hypertension. At follow-up 5-16 years later all showed normal growth, blood pressure and renal function, and only one child had low-grade albuminuria. Unilateral nephrectomy seems to be a safe and effective alternative to long-term hypotensive treatment.

Renovascular hypertension commencing during fetal life.

We report three infants with severe, early hypertension due to unilateral renovascular disease, whose cardiovascular changes, or polycythaemia, or both, indicated they had been affected as fetuses. All underwent unilateral nephrectomy, and had a similar histology, with patchy areas having relatively normal glomeruli but immature proximal tubules. This pattern may be a marker for renovascular disease in fetal life.

Acute appendicitis occurring immediately post-renal transplant.

A 10-yr-old boy who presented with vomiting and abdominal pain 12 days after an uneventful renal transplant had no identifiable transplant-related cause for these symptoms. Four days later a perforated appendix was diagnosed. His case illustrates that common abdominal pathologies may present differently in immunosuppressed, transplanted patients, causing diagnostic delay.