The rationale and design of Insight into Nephrotic Syndrome: Investigating Genes, Health and Therapeutics (INSIGHT): a prospective cohort study of childhood nephrotic syndrome

Incidence and Pathological Patterns of Nephrotic Syndrome among Infants and Children: A Systematic Review

Nephrotic syndrome (NS) is known to be a prevalent chronic illness in young patients. Periorbital swelling in children with this condition is a recurring symptom, either with or without generalized edema. The current study aimed to examine the incidence and pattern of nephrotic syndrome in infants and children by thoroughly examining the recently available literature. A thorough search of PubMed, SCOPUS, Web of Science, Science Direct, and Google Scholar was conducted, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model, to find pertinent material. The Rayyan software (Qatar Computing Research Institute, Ar-Rayyan, Qatar) was utilized during the whole process. Data from a total of 1418 patients from nine trials were considered in this study. Numerous factors influenced the incidence, mean age, sex dominance, and histological patterns in various sample groups. The current findings conclude that variations in socioeconomic, regional, and genetic factors influence the development and pattern of these diseases. The prevalence of pediatric renal disorders differs throughout countries. Season of occurrence, response to corticosteroid treatment, and histopathologic findings appear to differ amongst the diagnosed cases.

Family functioning and quality of life among children with nephrotic syndrome during the first pandemic wave

BACKGROUND

During the SARS-CoV-2 global pandemic, one of the longest lockdowns worldwide occurred in Ontario, Canada, during the first wave. For parents and children managing care at home and at risk for COVID-19, the impact on their psychosocial functioning is unknown.

METHODS

A total of 122 families of children aged 2-18 years were enrolled as part of the prospective cohort of childhood nephrotic syndrome and completed a survey during the first wave of the pandemic (August 21-December 10), 2020. In a subset, 107 families had data available pre-pandemic to assess change. Validated measures included the McMaster Family Assessment Device (FAD) for parents and children ≥ 12 years for family functioning, the Patient Health Questionnaire for Depression and Anxiety (PHQ-4) for both parent and child, and Pediatric Quality of Life Inventory (PEDSQL™-V4) for children only. Scores were compared using Student's t-test or the Mann-Whitney U test, as appropriate.

RESULTS

Among the 107 children, 71% were male with a mean age of 9 years old at the time of questionnaire completion, and the mean age of parents was 41 years old. Parents and children reported that family functioning improved during COVID (parent: p < 0.01; child: p = 0.05). Children's overall HRQOL declined (p = 0.04), specifically increased sleep disruption (p = 0.01). Increasing child age was associated with a greater sleep disruption (β =  - 1.6 [IQR: - 2.6, - 0.67]) and a related decrease in QOL (β =  - 1.0 [IQR: - 1.7, - 0.2]), adjusted for sex.

CONCLUSIONS

Despite the positive effects of family dynamics during the first wave, there were negative effects of sleep disruptions and reduced quality of life in children, especially among older children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Common Risk Variants in AHI1 Are Associated With Childhood Steroid Sensitive Nephrotic Syndrome

Introduction

Steroid-sensitive nephrotic syndrome (SSNS) is the most common form of kidney disease in children worldwide. Genome-wide association studies (GWAS) have demonstrated the association of SSNS with genetic variation at HLA-DQ/DR and have identified several non-HLA loci that aid in further understanding of disease pathophysiology. We sought to identify additional genetic loci associated with SSNS in children of Sri Lankan and European ancestry.

Methods

We conducted a GWAS in a cohort of Sri Lankan individuals comprising 420 pediatric patients with SSNS and 2339 genetic ancestry matched controls obtained from the UK Biobank. We then performed a transethnic meta-analysis with a previously reported European cohort of 422 pediatric patients and 5642 controls.

Results

Our GWAS confirmed the previously reported association of SSNS with HLA-DR/DQ (rs9271602, P = 1.12 × 10-27, odds ratio [OR] = 2.75). Transethnic meta-analysis replicated these findings and identified a novel association at AHI1 (rs2746432, P = 2.79 × 10-8, OR = 1.37), which was also replicated in an independent South Asian cohort. AHI1 is implicated in ciliary protein transport and immune dysregulation, with rare variation in this gene contributing to Joubert syndrome type 3.

Conclusions

Common variation in AHI1 confers risk of the development of SSNS in both Sri Lankan and European populations. The association with common variation in AHI1 further supports the role of immune dysregulation in the pathogenesis of SSNS and demonstrates that variation across the allele frequency spectrum in a gene can contribute to disparate monogenic and polygenic diseases.

Shared genetic risk across different presentations of gene test-negative idiopathic nephrotic syndrome

BACKGROUND

Idiop athic nephrotic syndrome (INS) is classified in children according to response to initial corticosteroid therapy into steroid-sensitive (SSNS) and steroid-resistant nephrotic syndrome (SRNS), and in adults according to histology into minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). However, there is well-recognised phenotypic overlap between these entities. Genome-wide association studies (GWAS) have shown a strong association between SSNS and variation at HLA, suggesting an underlying immunological basis. We sought to determine whether a risk score generated from genetic variants associated with SSNS could be used to gain insight into the pathophysiology of INS presenting in other ways.

METHODS

We developed an SSNS genetic risk score (SSNS-GRS) from the five variants independently associated with childhood SSNS in a previous European GWAS. We quantified SSNS-GRS in independent cohorts of European individuals with childhood SSNS, non-monogenic SRNS, MCD, and FSGS, and contrasted them with SSNS-GRS quantified in individuals with monogenic SRNS, membranous nephropathy (a different immune-mediated disease-causing nephrotic syndrome), and healthy controls.

RESULTS

The SSNS-GRS was significantly elevated in cohorts with SSNS, non-monogenic SRNS, MCD, and FSGS compared to healthy participants and those with membranous nephropathy. The SSNS-GRS in all cohorts with non-monogenic INS were also significantly elevated compared to those with monogenic SRNS.

CONCLUSIONS

The shared genetic risk factors among patients with different presentations of INS strongly suggests a shared autoimmune pathogenesis when monogenic causes are excluded. Use of the SSNS-GRS, in addition to testing for monogenic causes, may help to classify patients presenting with INS. A higher resolution version of the Graphical abstract is available as Supplementary information.

Analysis of the association of NPHS2 and ACTN4 genes polymorphism with nephrotic syndrome in Egyptian children

BACKGROUND

One of the most common kidney illnesses in developing countries is pediatric nephrotic syndrome (PNS), which is frequently associated with dyslipidemia and edema. The rapid discovery of genes related to NS has aided in the understanding of the molecular mechanics of glomerular filtration. The goal of this study is to determine the relationship between NPHS2 and ACTN4 in PNS youngsters.

METHODS

A study with 100 NS children and 100 healthy matched volunteers was conducted. Genomic DNA was extracted from peripheral blood. Single-nucleotide polymorphisms were genotyped using ARMS-PCR.

RESULTS

A substantial decline in the level of albumin was found in NS cases (P < 0.001) Further on, a significantly difference in T.C and TG level between healthy and NS patient. Molecular study showed a highly significant difference of NS patients from controls regarding NPHS2 rs3829795 polymorphic genotypes as the GA heterozygous genotype shows highly significant difference from controls (P < 0.001) as well as GA + AA genotypes (P < 0.001) in comparison with GG genotype. Regarding rs2274625, The GA heterozygous genotype showed no statistically significant difference between genotypes and alleles with NS (P = 0.246). Association of AG haplotype NPHS2 rs3829795-rs2274625 haplotypes found a significant association with the risk of developing NS (P = 0.008). Concerning the ACTN4 rs121908415 SNP, there was no link between this mutation and NS children.

CONCLUSION

The correlation of AG haplotype NPHS2 rs3829795-rs2274625 haplotypes identified a strong association with the likelihood of getting NS, according to our findings. There was no connection found between the ACTN4 rs121908415 SNP and NS children.

Therapeutic trials in difficult to treat steroid sensitive nephrotic syndrome: challenges and future directions

Steroid sensitive nephrotic syndrome is a common condition in pediatric nephrology, and most children have excellent outcomes. Yet, 50% of children will require steroid-sparing agents due to frequently relapsing disease and may suffer consequences from steroid dependence or use of steroid-sparing agents. Several steroid-sparing therapeutic agents are available with few high quality randomized controlled trials to compare efficacy leading to reliance on observational data for clinical guidance. Reported trials focus on short-term outcomes such as time to first relapse, relapse rates up to 1-2 years of follow-up, and few have studied long-term remission. Trial designs often do not consider inter-individual variability, and differing response to treatments may occur due to heterogeneity in pathogenic mechanisms, and genetic and environmental influences. Strategies are proposed to improve the quantity and quality of trials in steroid sensitive nephrotic syndrome with integration of biomarkers, novel trial designs, and standardized outcomes, especially for long-term remission. Collaborative efforts among international trial networks will help move us toward a shared goal of finding a cure for children with nephrotic syndrome.

Relationship between H. pylori infection and some other risk factors in the incidence and recurrence of idiopathic nephrotic syndrome in children

Background

Idiopathic nephrotic syndrome (INS) is one of the chronic diseases in children and it is important to identify its related factors. The present study aimed at investigating the relationship between H. pylori infection and the incidence and recurrence of idiopathic nephrotic syndrome in children.

Methods

The total number of case participants was 40 and the total number of control participants was 41. Based on the number of cases of nephrotic syndrome (NS), the same number of healthy children of the same age and gender were selected as the control group. The information and data collected include demographic characteristics of patients, duration of disease, number of recurrences, blood pressure and blood excretion in urine, height, and weight, and presence of gastrointestinal symptoms on the checklist. The data were entered into SPSS and analyzed at a significance level of 05.

Results

From 81 participants in the study, 11 (13.75%) cases were H. pylori positive, of whom 7 (17.5%) cases were in the control group and 4 (10%) cases were in the patients' group. There was no significant difference between the two groups in terms of H. pylori infection rate (P = 0.863). Moreover, there were no significant differences between the patients suffering from the nephrotic syndrome in terms of height, weight, blood pressure, hematuria, duration and recurrence of the disease (p>0.05).

Conclusion

According to the evaluations performed in the present study, there was no relationship between low birth weight, blood pressure, disease duration, and disease recurrence with NS.

Evaluation of corneal and lens densitometry with Pentacam HR in children with Nephrotic Syndrome: A controlled, prospective study

BACKGROUND

This study aimed to compare the corneal and lens densitometry values between children with Nephrotic Syndrome (NS) and healthy individuals.

METHODS

This cross-sectional comparative study included 23 patients with NS and 26 healthy controls. Corneal topographic and corneal and lens densitometric values were measured using Pentacam HR. Densitometry measurements in different layers were analyzed and compared between groups. Correlations between steroid cumulative dose, age at diagnosis of the disease, duration of disease, number of relapses, and patients' densitometries values were evaluated.

RESULTS

The measurements of the keratometry, horizontal white-to-white, and iridocorneal angle values were significantly different between groups (p < 0.05). The 0-2 mm and 2-6 mm anterior corneal densitometry values were significantly higher in NS patients. (p = 0.009 and p = 0.033, respectively). The lens densitometry values of all zones were higher in the eyes with NS but there was no statistically significant difference from the healthy control eyes (p > 0.05). There was a positive strong correlation between the cumulative steroid dose and the posterior lens zone densitometry, a positive weak correlation between the number of attacks and anterior corneal densitometry, and between disease duration and central corneal densitometry and average lens density.

CONCLUSION

In eyes with NS, changes occur in corneal and lens densitometry in correlation with disease duration, number of attacks, and cumulative steroid dose. Significant density changes were detected especially in the anterior cornea and central 0-6 mm area.

Genetic variant in the 5' untranslated region of endothelin1 (EDN1) gene in children with primary nephrotic syndrome

Endothelin-1 plays a crucial role in the pathophysiology of nephrotic syndrome (NS) in children. The primary purpose of this study is to evaluate the contribution of the EDN1 (3A/4A; rs1800997) variant to the risk of nephrotic syndrome. This study involves 200 participants (100 healthy controls, 50 steroid-sensitive nephrotic syndromes [SSNS] patients, and 50 steroid-resistant nephrotic syndromes [SRNS] patients]. Genomic DNA has been characterized using the PCR-RFLP technique. The predominant genotype that is common in this study population was the EDN1 3A/3A genotype (NS [75%] and healthy controls [88%]). The prevalence of EDN1 3A/4A genotype and EDN1 4A allele was significantly increased among NS patients compared with healthy subjects (p-value < 0.05). Furthermore, the frequency of the EDN1 (3A/4A; rs1800997) variant was statistically significant among SRNS patients (p-value < 0.05). The EDN1 3A/4A genotype and the EDN1 4A allele were identified as independent risk factors of the nephrotic syndrome among children.

Population-based identification and temporal trend of children with primary nephrotic syndrome: The Kaiser Permanente nephrotic syndrome study

INTRODUCTION

Limited population-based data exist about children with primary nephrotic syndrome (NS).

METHODS

We identified a cohort of children with primary NS receiving care in Kaiser Permanente Northern California, an integrated healthcare delivery system caring for >750,000 children. We identified all children <18 years between 1996 and 2012 who had nephrotic range proteinuria (urine ACR>3500 mg/g, urine PCR>3.5 mg/mg, 24-hour urine protein>3500 mg or urine dipstick>300 mg/dL) in laboratory databases or a diagnosis of NS in electronic health records. Nephrologists reviewed health records for clinical presentation and laboratory and biopsy results to confirm primary NS.

RESULTS

Among 365 cases of confirmed NS, 179 had confirmed primary NS attributed to presumed minimal change disease (MCD) (72%), focal segmental glomerulosclerosis (FSGS) (23%) or membranous nephropathy (MN) (5%). The overall incidence of primary NS was 1.47 (95% Confidence Interval:1.27-1.70) per 100,000 person-years. Biopsy data were available in 40% of cases. Median age for patients with primary NS was 6.9 (interquartile range:3.7 to 12.9) years, 43% were female and 26% were white, 13% black, 17% Asian/Pacific Islander, and 32% Hispanic.

CONCLUSION

This population-based identification of children with primary NS leveraging electronic health records can provide a unique approach and platform for describing the natural history of NS and identifying determinants of outcomes in children with primary NS.

Evaluation of Helicobacter pylori eradication on the course of childhood nephrotic syndrome and its response to treatment

Background: Idiopathic nephrotic syndrome is one of the most common glomerular diseases, which may be secondary to infections or systemic diseases. The aim of this study was to evaluate the effect of Helicobacter pylori (H. pylori) eradication on childhood nephrotic syndrome.

Methods: In this randomized controlled clinical trial study, 38 children with concomitant idiopathic nephrotic syndrome and H. pylori infection were divided into 2 equal groups; the intervention group received a cotreatment for both diseases and the control group received only nephrotic syndrome treatment. Patients were followed for 6 months. Data were analyzed using SPSS 21 software. Chi square test, Fisher exact test, and student t test were used. P value <0.05 was considered statistically significant.

Results: The mean interval time from treatment to the recovery of nephrotic syndrome was 48.36±14.48 days in the intervention group and 51.68± 17.32 days in control groups, which was shorter in the intervention group, but not statistically significant. The recurrence of nephrotic syndrome and the mean number of recurrences in the intervention group were lower than the control group, but were not statistically significant. The frequency of diarrhea in the intervention group was significantly higher than the control group (p=0.003).

Conclusion: In children with concomitant idiopathic nephrotic syndrome and H. pylori infection, the treatment of both diseases may accelerate the recovery and decrease the recurrence of nephrotic syndrome.

Impact of steroids and steroid-sparing agents on quality of life in children with nephrotic syndrome

BACKGROUND

Steroids and/or steroid-sparing medications are commonly used for nephrotic syndrome treatment; however, the impact of these medications on health-related quality of life over time is not well described.

METHODS

Longitudinal cohort is up to 5 years where children were assessed with baseline and annual Pediatric Quality of Life Inventory questionnaire. A mixed-effects linear regression determined differences in scores among children receiving steroids and/or steroid-sparing agents for at least 30 days compared with those not on medication at 1, 3, 6, and 12 months prior to assessment.

RESULTS

Among 295 children, 64% were male, with a median age of 3.7 (interquartile range [IQR], 2.7, 5.9) years at diagnosis, and comprised 25% Europeans, 40% South Asians, and 8% East/Southeast Asians. Adjusted HRQOL scores were reduced among children taking steroids and steroid-sparing agents among 705 HRQOL measures (median 2 [IQR, 1, 3] per child). Compared to children without medication, steroid and steroid-sparing agent use up to 12 months prior to assessment were associated with an overall HRQOL drop of 3.17 (95% confidence interval [CI], - 5.25, - 1.08) and 3.18 (95% CI, - 5.24, - 1.12), respectively, after adjustment. Functioning domain scores were reduced by 4.41 points (95% CI, - 6.57, - 2.25) in children on steroids, whereas fatigue domain scores were reduced by 5.47 points (95% CI, - 9.28, - 1.67) in children on steroid-sparing agents after adjustment.

CONCLUSIONS

HRQOL is consistently decreased in children receiving steroids and steroid-sparing agents, with differential effects on functioning and fatigue. Counseling families on possible effects of prolonged treatment periods is important in the management of childhood nephrotic syndrome.

Review on long-term non-renal complications of childhood nephrotic syndrome

BACKGROUND

Nephrotic syndrome (NS) is the most common glomerular childhood disease. A body of literature has described the long-term renal prognosis of childhood-onset idiopathic NS. However, the nonrenal outcomes have not been studied as much.

AIM

We aimed to discuss the long-term non-renal outcomes of childhood NS, highlighting studies with a follow-up period of more than 10 years.

RESULTS

We reviewed the literature and found that a number of immunosuppressive agents have stopped inflammation, stabilised the podocyte cytoskeleton and reduce proteinuria. However, prolonged treatment has frequently been associated with a high risk of renal and non-renal complications in patients with a complicated disease course, defined as frequent relapses or steroid dependency. Non-renal complications may include impaired longitudinal growth and pubertal development, undesirable fertility outcomes, ocular complications, bone mineral diseases and potential malignancies.

CONCLUSION

This review discusses and summarises the non-renal outcomes of idiopathic childhood NS.

Prediction of Short- and Long-Term Outcomes in Childhood Nephrotic Syndrome

Introduction

It is unknown whether steroid sensitivity and other putative risk factors collected at baseline can predict the disease course of idiopathic nephrotic syndrome in childhood. We determined whether demographic, clinical, and family reported factors at presentation can predict outcomes in idiopathic nephrotic syndrome.

Methods

An observational cohort of 631 children aged 1 to 18 years diagnosed with idiopathic nephrotic syndrome between 1993 and 2016 were followed up until clinic discharge, 18 years of age, end-stage kidney disease (ESKD), or the last clinic visit. Baseline characteristics were age, sex, ethnicity, and initial steroid sensitivity. Of these, 287 (38%) children also reported any family history of kidney disease, preceding infection, microscopic hematuria, and history of asthma/allergies. The outcomes were complete remission after initial steroid course, need for a second-line agent, frequently relapsing disease, and long-term remission. The discriminatory power of the models was described using the c-statistic.

Results

Overall, 25.7% of children had no further disease after their initial steroid course. In addition, 31.2% developed frequently relapsing disease; however, 77.7% were disease-free at 18 years of age. Furthermore, 1% of children progressed to ESKD. Logistic regression modeling using the different baseline exposures did not significantly improve the prediction of outcomes relative to the observed frequencies (maximum c-statistic, 0.63; 95% confidence interval [CI], 0.59–0.67). The addition of steroid sensitivity did not improve outcome prediction of long-term outcomes (c-statistic, 0.63; 95% CI, 0.54–0.70).

Conclusions

Demographic, clinical, and family reported characteristics, specifically steroid sensitivity, are not useful in predicting relapse rates or long-term remission in idiopathic nephrotic syndrome. Further studies are needed to address factors that contribute to long-term health.

Association of low birth weight and prematurity with clinical outcomes of childhood nephrotic syndrome: a prospective cohort study

BACKGROUND

Low birth weight (LBW)/prematurity have been proposed as risk factors for the development of kidney disease in adulthood. Whether there is an association between LBW/prematurity and poor renal outcomes in childhood onset nephrotic syndrome remains unknown.

METHODS

Children with nephrotic syndrome diagnosed between 1 and 18 years of age were followed prospectively from 1996 to 2016 at The Hospital for Sick Children (N = 377). LBW/prematurity was defined as birth weight < 2500 g or gestational age < 36 weeks. Normal birth weight (NBW) was defined as birth weight ≥ 2500 g. Measures evaluating clinical course of nephrotic syndrome include initial steroid-resistant nephrotic syndrome (SRNS), time to first relapse, and frequently relapsing nephrotic syndrome. Kaplan-Meier survival analysis, logistic regression, and Cox proportional hazards regression were used to determine the association of LBW/prematurity with clinical outcomes.

RESULTS

Median birth weights in LBW/premature (n = 46) and NBW (n = 331) children were 2098 g (interquartile range [IQR] 1700-2325 g) and 3317 g (IQR 2977-3685 g), respectively. Odds of having SRNS were 3.78 (95% confidence interval [CI] 1.28-11.21) times higher among LBW/premature children than NBW children. An 8% decrease in odds of developing SRNS was observed for every 100 g increase in birth weight (adjusted odds ratio [OR] 0.92; 95% CI 0.86-0.98). Median time to first relapse did not differ (hazard ratio [HR] 0.89; 95% CI 0.53-1.16).

CONCLUSIONS

LBW/premature children were more likely to develop SRNS but did not have a difference in time to first relapse with NBW children. Understanding the impact and mechanism of birth weight and steroid-resistant disease needs further study.

Prospects of genetic testing for steroid-resistant nephrotic syndrome in Nigerian children: a narrative review of challenges and opportunities

The prevalence of childhood steroid-resistant nephrotic syndrome (SRNS) ranges from 35% to 92%. This steroid resistance among Nigerian children also reflects underlying renal histopathology, revealing a rare minimal-change disease and a varying burden of membranoproliferative glomerulonephritis and focal segmental glomerulosclerosis (FSGS). FSGS tends to progress to end-stage kidney disease, which requires dialysis and/or renal transplantation. While knowledge of the molecular basis of NS is evolving, recent data support the role of mutant genes that otherwise maintain the structural and functional composition of the glomerular filtration barrier to account for many monogenic forms of FSGS. With the advent of next-generation sequencing, >39 genes are currently associated with SRNS, and the number is likely to increase in the near future. Monogenic FSGS is primarily resistant to steroids, and this foreknowledge obviates the need for steroids, other immunosuppressive therapy, and renal biopsy. Therefore, a multidisciplinary collaboration among cell biologists, molecular physiologists, geneticists, and clinicians holds prospects of fine-tuning the management of SRNS caused by known mutant genes. This article describes the genetics of NS/SRNS in childhood and also gives a narrative review of the challenges and opportunities for molecular testing among children with SRNS in Nigeria. For these children to benefit from genetic diagnosis, Nigeria must aspire to have and develop the manpower and infrastructure required for medical genetics and genomic medicine, leveraging on her existing experiences in genomic medicine. Concerted efforts can be put in place to increase the number of enrollees in Nigeria’s National Health Insurance Scheme (NHIS). The scope of the NHIS can be expanded to cater for the expensive bill of genetic testing within or outside the structure of the National Renal Care Policy proposed by Nigerian nephrologists.

Prevalence of Asthma and Allergies and Risk of Relapse in Childhood Nephrotic Syndrome: Insight into Nephrotic Syndrome Cohort

OBJECTIVE

To determine the lifetime prevalence of allergies in childhood nephrotic syndrome, the seasonality of presentation and relapses, and the impact of allergies on subsequent relapses.

STUDY DESIGN

In a longitudinal cohort of children with nephrotic syndrome (ages 1-18 years), assessment for allergic diseases was conducted using the validated and modified version of the International Study of Asthma and Allergies in Childhood questionnaire at enrollment. Outcomes included frequently relapsing nephrotic syndrome, relapse rates, and the relapse-free duration after initial steroid therapy.

RESULTS

Among 277 participants, the majority were male (65%) with a median age of 3.7 years (IQR 2.8-5.8) at presentation. A total of 64% reported lifetime allergies with 20% having asthma, 33% wheezing, 27% eczema, and 24% rhinitis. Over 3.3 years of follow-up, presence of asthma and allergies was not associated with frequently relapsing nephrotic syndrome (OR 1.20; 95% CI 0.60, 2.40), higher relapse rates (relative risk 0.95; 95% CI 0.71, 1.27), or risk of first relapse (hazard ratio 1.10; 95% CI 0.83, 1.47) compared with those with no history of allergic diseases. There was also no seasonal variation evident at initial presentation or frequency of relapses.

CONCLUSIONS

Two-thirds of children with nephrotic syndrome at presentation have allergic symptoms and asthma; however, neither are associated with an increased frequency of relapses.

The long-term outcome of childhood nephrotic syndrome in Germany: a cross-sectional study

BACKGROUND

Long-term outcomes of children with nephrotic syndrome have not been well described in the literature.

METHODS

Cross-sectional study data analysis of n = 43 patients with steroid-sensitive (SSNS) and n = 7 patients with steroid-resistant (SRNS) nephrotic syndrome were retrospectively collected; patients were clinically examined at a follow-up visit (FUV), on average 30 years after onset, there was the longest follow-up period to date.

RESULTS

The mean age at FUV was 33.6 years (14.4-50.8 years, n = 41). The mean age of patients with SSNS at onset was 4.7 years (median 3.8 years (1.2-14.5 years), the mean number of relapses was 5.8 (0 to 29 relapses). Seven patients (16.3%) had no relapses. Eleven patients were "frequent relapsers" (25.6%) and four patients still had relapses beyond the age of 18 years. Except of cataracts and arterial hypertension, there were no negative long-term outcomes and only one patient was using immunosuppressant therapy at FUV. 55% of patients suffered from allergies and 47.5% had hypercholesterolemia. Two patients suffered a heart attack in adulthood. A younger age at onset (< 4 years) was a risk factor for frequent relapses. An early relapse (within 6 months after onset) was a risk factor and a low birth weight was not a significant risk factor for a complicated NS course. The mean age of patients with SRNS at onset was 4.6 ± 4.4 years and 27.5 ± 9.9 years at FUV. Three patients received kidney transplantations.

CONCLUSIONS

The positive long-term prognosis of SSNS can reduce the concern of parents about the probability of the child developing a chronic renal disease during the clinical course after onset.

Nephrotic syndrome in infants and children: pathophysiology and management

Nephrotic syndrome is defined by nephrotic-range proteinuria (≥40 mg/m²/hour or urine protein/creatinine ratio ≥200 mg/mL or 3+ protein on urine dipstick), hypoalbuminaemia (<25 g/L) and oedema. This review focuses on the classification, epidemiology, pathophysiology, management strategies and prognosis of idiopathic nephrotic syndrome of childhood, and includes a brief overview of the congenital forms.

The incidence of the nephrotic syndrome in childhood in Germany

BACKGROUND

The incidence of childhood nephrotic syndrome (NS) in Germany is not well known.

METHODS

An ESPED-based nationwide collection of epidemiological data of children in 2005 and 2006.

RESULT

The mean age of NS at onset was 5.5 ± 3.7 years. The gender ratio of boys to girls was 1.8:1. The average length of stay was 15.5 ± 11.2 days, with younger children remaining significantly longer in hospital. Steroid-resistance was more common in children ≥8 years (p = 0.023). Focal-segmental glomerulosclerosis (FSGS) was more common in children >10 years (p = 0.029). The ratio of males to females with FSGS was 1:1.9, thus the FSGS risk for girls at onset was 3.3-times greater. Considering the available data, the incidence of NS in Germany is 1.2/100,000 in the population <18 years, of which 1.0/100,000 are steroid-sensitive.

CONCLUSION

Compared with international data, which primarily focused on regional and small populations, this is the largest study about the incidence of the childhood NS.

Parental Health Literacy and Outcomes of Childhood Nephrotic Syndrome

OBJECTIVE

Determine the association of parental health literacy with treatment response among children with nephrotic syndrome.

METHODS

This was a cohort study of children aged 1-18 with nephrotic syndrome and their parent. Health literacy was measured using the validated Short Test of Functional Health Literacy in Adults assessing reading comprehension and numeracy. Outcomes included initial relapse-free period, frequently relapsing disease, relapse rate, second-line medication use, and complete remission after therapy.

RESULTS

Of 190 parents, 80% had adequate health literacy (score >67 of 100), and higher scores were not correlated with higher education. Almost all achieved perfect numeracy scores (>86%); numeracy was not associated with outcomes. After adjusting for immigration, education, and income, higher reading comprehension scores (tertile 3) compared with lower scores (tertile 1) were significantly associated with lower risk of first relapse (hazard ratio 0.67, 95% confidence interval [CI] 0.48-0.94, P trend = .02), lower odds of frequently relapsing disease (odds ratio [OR] 0.38, 95% CI 0.21-0.70, P trend = .002), lower relapse rate (rate ratio 0.77, 95% CI 0.73-0.80, P trend < .001), and higher odds of complete remission after both initial steroids and cyclophosphamide (OR 2.07, 95% CI 1.36-3.16, P trend = .003; OR 5.97, 95% CI 2.42-14.7, P trend < .001).

CONCLUSIONS

Lower parental health literacy, specifically reading comprehension, is associated with higher relapse rates among children with nephrotic syndrome and fewer achieving complete remission. This underscores the importance of assessing and targeting health literacy for chronic management of childhood-onset diseases.

Ethnic Differences in Incidence and Outcomes of Childhood Nephrotic Syndrome

BACKGROUND AND OBJECTIVES

Ethnic differences in outcomes among children with nephrotic syndrome are unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a longitudinal study at a single regional pediatric center comparing ethnic differences in incidence from 2001 to 2011 census data and longitudinal outcomes, including relapse rates, time to first relapse, frequently relapsing disease, and use of cyclophosphamide. Among 711 children, 24% were European, 33% were South Asian, 10% were East/Southeast Asian, and 33% were of other origins.

RESULTS

Over 10 years, the overall incidence increased from 1.99/100,000 to 4.71/100,000 among children ages 1-18 years old. In 2011, South Asians had a higher incidence rate ratio of 6.61 (95% confidence interval, 3.16 to 15.1) compared with Europeans. East/Southeast Asians had a similar incidence rate ratio (0.76; 95% confidence interval, 0.13 to 2.94) to Europeans. We determined outcomes in 455 children from the three largest ethnic groups with steroid-sensitive disease over a median of 4 years. South Asian and East/Southeast Asian children had significantly lower odds of frequently relapsing disease at 12 months (South Asian: adjusted odds ratio; 0.55; 95% confidence interval, 0.39 to 0.77; East/Southeast Asian: adjusted odds ratio; 0.42; 95% confidence interval, 0.34 to 0.51), fewer subsequent relapses (South Asian: adjusted odds ratio; 0.64; 95% confidence interval, 0.50 to 0.81; East/Southeast Asian: adjusted odds ratio; 0.47; 95% confidence interval, 0.24 to 0.91), lower risk of a first relapse (South Asian: adjusted hazard ratio, 0.74; 95% confidence interval, 0.67 to 0.83; East/Southeast Asian: adjusted hazard ratio, 0.65; 95% CI, 0.63 to 0.68), and lower use of cyclophosphamide (South Asian: adjusted hazard ratio, 0.82; 95% confidence interval, 0.53 to 1.28; East/Southeast Asian: adjusted hazard ratio, 0.54; 95% confidence interval, 0.41 to 0.71) compared with European children.

CONCLUSIONS

Despite the higher incidence among South Asians, South and East/Southeast Asian children have significantly less complicated clinical outcomes compared with Europeans.

International Network of Chronic Kidney Disease cohort studies (iNET-CKD): a global network of chronic kidney disease cohorts

Background

Chronic kidney disease (CKD) is a global health burden, yet it is still underrepresented within public health agendas in many countries. Studies focusing on the natural history of CKD are challenging to design and conduct, because of the long time-course of disease progression, a wide variation in etiologies, and a large amount of clinical variability among individuals with CKD. With the difference in health-related behaviors, healthcare delivery, genetics, and environmental exposures, this variability is greater across countries than within one locale and may not be captured effectively in a single study.

Methods

Studies were invited to join the network. Prerequisites for membership included: 1) observational designs with a priori hypotheses and defined study objectives, patient-level information, prospective data acquisition and collection of bio-samples, all focused on predialysis CKD patients; 2) target sample sizes of 1,000 patients for adult cohorts and 300 for pediatric cohorts; and 3) minimum follow-up of three years. Participating studies were surveyed regarding design, data, and biosample resources.

Results

Twelve prospective cohort studies and two registries covering 21 countries were included. Participants age ranges from >2 to >70 years at inclusion, CKD severity ranges from stage 2 to stage 5. Patient data and biosamples (not available in the registry studies) are measured yearly or biennially. Many studies included multiple ethnicities; cohort size ranges from 400 to more than 13,000 participants. Studies’ areas of emphasis all include but are not limited to renal outcomes, such as progression to ESRD and death.

Conclusions

iNET-CKD (International Network of CKD cohort studies) was established, to promote collaborative research, foster exchange of expertise, and create opportunities for research training. Participating studies have many commonalities that will facilitate comparative research; however, we also observed substantial differences. The diversity we observed across studies within this network will be able to be leveraged to identify genetic, behavioral, and health services factors associated with the course of CKD. With an emerging infrastructure to facilitate interactions among the investigators of iNET-CKD and a broadly defined research agenda, we are confident that there will be great opportunity for productive collaborative investigations involving cohorts of individuals with CKD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0335-2) contains supplementary material, which is available to authorized users.

Parental attitudes to genetic testing differ by ethnicity and immigration in childhood nephrotic syndrome: a cross-sectional study

Background

Studies in the USA report differences in opinion among parents of different ethnic groups toward genetic testing for their child; however, there are no studies that address this issue in the diverse ethnic and immigrant population in Canada.

Objective

This study aims to determine whether ethnicity and immigration status influences parental interest in clinical genetic testing for a potentially progressive kidney disease.

Design

This is a cross-sectional study.

Setting

Participants were recruited from the Greater Toronto Area, Canada.

Participants

The study included 320 parents of children ages 1–18 years with nephrotic syndrome enrolled in the Insight into Nephrotic Syndrome: Investigating Genes, Health and Therapeutics (INSIGHT) observational cohort study.

Measurements

Demographic, ethnicity, immigration, and child specific factors as well as interest in genetic testing were collected through self-reported questionnaires administered at baseline study visit.

Methods

Logistic regression models were used to examine association of ethnicity and immigration status with interest in genetic testing.

Results

The majority of parents (85 %) were interested in genetic testing for their child. South Asian and East/Southeast Asian parents had 74 and 76 % lower odds of agreeing to genetic testing when compared to Europeans (odds ratio (OR) 0.26, 95 % confidence interval (CI) 0.10–0.68; OR 0.24, 95 % CI 0.07–0.79, respectively) after controlling for age and sex of child, age and education level of parent, initial steroid resistance, and duration of time in Canada. Immigrants to Canada also had significantly lower odds (OR 0.29, 95 % CI 0.12–0.72) of agreeing to genetic testing after similar adjustment. Higher education level was not associated with greater interest in genetic testing (OR 1.24, 95 % CI 0.64–2.42).

Limitations

Participants have already agreed to aggregate genetic testing for research purposes as part of enrolment in INSIGHT study.

Conclusion

While majority of parents were interested in genetic testing for their child, immigrants, particularly South Asians and East/Southeast Asians, were more likely to decline genetic testing. Genetic counseling needs to be tailored to address specific concerns in these parental groups to maximize informed decision-making in the clinical setting.

Trial registration

ClinicalTrials.gov, NCT01605266

Ethnic Differences in Childhood Nephrotic Syndrome

Nephrotic syndrome is a common glomerular disease in children with significant variability in both incidence and steroid responsiveness among various ethnic groups. The average incidence of nephrotic syndrome is 2-16.9 per 100,000 children worldwide. Understanding the variability by ethnicity may point to potential factors leading to nephrotic syndrome, which remains elusive, and may highlight factors accounting for differences in medication response. The emerging role of genetic factors associated with steroid responsive and steroid-resistant forms of nephrotic syndrome within an ethnic group can provide insight into potential biological mechanisms leading to disease. For example, among African-Americans, the risk variants in APOL1 are associated with a more than 10-fold increase in risk of focal segmental glomerulosclerosis and high-risk carriers have a twofold greater risk of progression to end-stage renal disease. Ongoing collaborative studies should consider capturing data on self-reported ethnicity to understand differences in incidence and outcomes. In the future, the availability of whole-genome data will provide an excellent opportunity for new clinical and translational research in childhood nephrotic syndrome and lead to a better understanding of the disease.

The Canadian Childhood Nephrotic Syndrome (CHILDNEPH) Project: overview of design and methods

Background

Nephrotic syndrome is a commonly acquired kidney disease in children that causes significant morbidity due to recurrent episodes of heavy proteinuria. The management of childhood nephrotic syndrome is known to be highly variable among physicians and care centres.

Objectives

The primary objective of the study is to determine centre-, physician-, and patient-level characteristics associated with steroid exposure and length of steroid treatment. We will also determine the association of dose and duration of steroid treatment and time to first relapse as a secondary aim. An embedded qualitative study utilizing focus groups with health care providers will enrich the quantitative results by providing an understanding of the attitudes, beliefs and local contextual factors driving variation in care.

Design

Mixed-methods study; prospective observational cohort (quantitative component), with additional semi-structured focus groups of healthcare professionals (qualitative component).

Setting

National study, comprised of all 13 Canadian pediatric nephrology clinics.

Patients

400 patients under 18 years of age to be recruited over 2.5 years.

Measurements

Steroid doses for all episodes (first presentation, first and subsequent relapses) tracked over course of the study. Physician and centre-level characteristics catalogued, with reasons for treatment preferences documented during focus groups.

Methods

All patients tracked prospectively over the course of the study, with data comprising a prospective registry. One focus group at each site to enrich understanding of variation in care.

Limitations

Contamination of treatment protocols between physicians may occur as a result of concurrent focus groups.

Conclusions

Quantitative and qualitative results will be integrated at end of study and will collectively inform strategies for the development and implementation of standardized evidence-based protocols across centres.

Rho-GTPase Signalling in the Pathogenesis of Nephrotic Syndrome

Nephrotic syndrome (NS) is characterized by heavy proteinuria, hypoalbuminemia, and edema. The underlying causes of NS are diverse and are tied to inheritable and environmental factors. A common diagnostic marker for NS is effacement of podocyte foot processes. The formation and maintenance of foot processes are under the control of many signalling molecules including Rho-GTPases. Our knowledge of Rho-GTPases is based largely on the functions of three prototypic members: RhoA, Rac1, and Cdc42. In the event of podocyte injury, the rearrangement to the actin cytoskeleton is orchestrated largely by this family of proteins. The importance of maintaining proper actin dynamics in podocytes has led to much investigation as to how Rho-GTPases and their regulatory molecules form and maintain foot processes as a critical component of the kidney’s filtration barrier. Modern sequencing techniques have allowed for the identification of novel disease causing mutations in genes such as ARHGDIA, encoding Rho-GDIα. Continued use of whole exome sequencing has the potential to lead to the identification of new mutations in genes encoding Rho-GTPases or their regulatory proteins. Expanding our knowledge of the dynamic regulation of the actin network by Rho-GTPases in podocytes will pave the way for effective therapeutic options for NS patients.