Insights from the Chronic Kidney Disease in Children (CKiD) study

Longitudinal Relationship Between Anemia and Statural Growth Impairment in Children and Adolescents With Nonglomerular CKD: Findings From the Chronic Kidney Disease in Children (CKiD) Study

RATIONALE & OBJECTIVE

Anemia and statural growth impairment are both prevalent in children with nonglomerular chronic kidney disease (CKD) and are associated with poor quality of life and increased morbidity and mortality. However, to date no longitudinal studies have demonstrated a relationship between anemia and statural growth in this population.

STUDY DESIGN

The CKD in Children (CKiD) study is a multicenter prospective cohort study with over 15 years of follow-up observation.

SETTING & PARTICIPANTS

CKiD participants younger than 22 years with nonglomerular CKD who had not reached final adult height.

EXPOSURE

Age-, sex-, and race-specific hemoglobin z score.

OUTCOME

Age- and sex-specific height z score.

ANALYTICAL APPROACH

The relationship between hemoglobin and height was quantified using (1) multivariable repeated measures paired person-visit analysis, and (2) multivariable repeated measures linear mixed model analysis. Both models were adjusted for age, sex, body mass index, estimated glomerular filtration rate, acidosis, and medication use.

RESULTS

Overall, 67% of the 510 participants studied had declining hemoglobin z score trajectories over the follow-up period, which included 1,763 person-visits. Compared with average hemoglobin z scores of≥0, average hemoglobin z scores of less than -1.0 were independently associated with significant growth impairment at the subsequent study visit, with height z score decline ranging from 0.24 to 0.35. Importantly, in 50% of cases hemoglobin z scores of less than -1.0 corresponded to hemoglobin values higher than those used as cutoffs defining anemia in the KDIGO clinical practice guideline for anemia in CKD. When stratified by age, the magnitude of the association peaked in participants aged 9 years. In line with paired-visit analyses, our mixed model analysis demonstrated that in participants with baseline hemoglobin z score less than -1.0, a hemoglobin z score decline over the follow-up period was associated with a statistically significant concurrent decrease in height z score.

LIMITATIONS

Limited ability to infer causality.

CONCLUSIONS

Hemoglobin decline is associated with growth impairment over time in children with mild to moderate nonglomerular CKD, even before hemoglobin levels reach the cutoffs that are currently used to define anemia in this population.

Dipping at home: is it better, easier, and more convenient? A feasibility and acceptability study of a novel home urinalysis using a smartphone application

BACKGROUND

Monitoring proteinuria in patients with kidney disease is of crucial importance given its implications for long-term disease progression and clinical management. Leveraging digital health technology to provide a clinical grade urinalysis result from home holds the potential to greatly enhance the clinical experience and workflows for patients, caregivers, and providers. The goal of this study was to evaluate the acceptability and feasibility of a home-based urinalysis kit using a smartphone application.

METHODS

This is a prospective cohort study of children and young adults (5-21 years of age) at a single pediatric center. The study received ethical board approval. Families performed a home urine test using the Healthy.io smartphone app. The app was compared with standard of care of either home dipstick monitoring or urinalysis performed in clinic or a local laboratory. Patient satisfaction was compared between the new app and current practice.

RESULTS

A total of 103 children, 63 (61%) male and median age 10.9 years (inter-quartile range 7.8-14.2), were enrolled. Primary diagnosis included 47 (46%) glomerular disease, 48 (47%) non-glomerular kidney disease, and 8 (8%) kidney transplant recipients. One hundred and one (98%) patients reported being satisfied with the smartphone app compared to 41 (40%) patients who were satisfied with the current practice for urine protein monitoring (p < 0.0001). Positive themes identified included ease of use, convenience, and immediacy and accuracy of results.

CONCLUSIONS

The Healthy.io home urine testing app received very high rates of satisfaction among patients and caregivers compared to current practice and holds great potential to enhance patient-centered care. A higher resolution version of the Graphical abstract is available as Supplementary information.

Comparison of darbepoetin alpha and recombinant human erythropoietin for treatment of anemia in pediatric chronic kidney disease: a non-inferiority trial from India

To determine whether or not Darbepoetin alpha (DA) was non-inferior to recombinant human erythropoietin (rHuEPO) in the treatment of anemia in children with chronic kidney disease (CKD) stage 3-5 (on or not on dialysis). This was a randomized, open-label, two-arm, parallel group, active-controlled, non-inferiority trial conducted at a tertiary care center in New Delhi, India. Fifty patients of either gender (aged 1-18 years) with CKD stage 3-5 (on or not on dialysis) who had baseline hemoglobin (Hb) between 9 and 12 g/dL and were on stable erythropoietin therapy for at least 8 weeks were randomized (1:1) to either continue rHuEPO or switch to DA therapy for a period of 28 weeks. Doses were titrated in the initial 23 weeks to maintain the Hb between 11 and 12 g/dL, and efficacy was assessed between weeks 24 and 28. The primary efficacy outcome was the mean change in Hb between baseline and the evaluation period. In the intention-to-treat population (n = 50), the adjusted between-group difference in mean Hb change between the baseline and the evaluation period was 0.131 g/dL (95% CI: - 0.439 to 0.719, p = 0.629). The lower limit of the two-sided 95% CI for the difference in the mean change in Hb between the two treatment groups was well above the pre-specified non-inferiority margin of - 1.0 g/dL. Similar pattern of non-inferiority was seen for per protocol population. The safety profile of DA and rHuEPO was also comparable (injection site pain:rHuEPO-3, DA-7; p-0.296).   Conclusion: DA is non-inferior to rHuEPO for the treatment of anemia of CKD (stage 3-5) in pediatric population with a comparable safety profile.   Trial registration: ClinicalTrials.gov Identifier: NCT04959578 (retrospectively registered), Date: July 13, 2021. What is Known: • Limited studies showing darbepoetin alpha is effective in children as an erythropoiesis stimulating agent. • No RCT from Indian subcontinent addressing this topic. What is New: • Darbepoetin alpha is non inferior to recombinant human erythropoietin for treatment of anemia in children with CKD stage 3-5 (on or not on dialysis) with safety comparable to recombinant human erythropoietin. • A cost reduction of approximately 8.6% per patient by shifting to darbepoetin alpha.

Time to Rethink the Current Paradigm for Assessing Kidney Function in Drug Development and Beyond

Chronic kidney disease (CKD) is an important health issue that affects ~ 9.1% of the world adult population. Serum creatinine is the most commonly used biomarker for assessing kidney function and is utilized in different equations for estimating creatinine clearance or glomerular filtration rate (GFR). The Cockcroft-Gault formula for adults and "original" Schwartz formula for children have been the most commonly used equations for estimating kidney function during the last 3-4 decades. Introduction of standardized serum creatinine bioanalytical methodology has reduced interlaboratory variability but is not intended to be used with Cockcroft-Gault or original Schwartz equations. More accurate equations (for instance, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) for adults and bedside Schwartz or Chronic Kidney Disease in Children Schwartz equation for children) based on standardized serum creatinine values (and another biomarker-cystatin C) have been introduced and validated in recent years. Recently, the CKD-EPI equation refitted without a race variable was introduced. Clinical practice guidance in nephrology advocates a shift to these equations for managing health care of patients with CKD. The guidance also recommends use of albuminuria in addition to GFR for CKD diagnosis and management. Significant research with large data sets would be necessary to evaluate whether this paradigm would also be valuable in drug dose adjustments. This article attempts to highlight some important advancements in the field from a clinical pharmacology perspective and is a call to action to industry, regulators, and academia to rethink the current paradigm for assessing kidney function to enable dose recommendation in patients with CKD.

Etiology, Comorbidities, and Rate of Progression of Pediatric Chronic Kidney Disease: A Cohort Study

OBJECTIVES

To evaluate the etiology of pediatric chronic kidney disease (CKD), assess comorbidities, and identify rate of progression of CKD and its risk factors.

METHODS

Children aged 2-18 y with the Kidney Disease Improving Global Outcome (KDIGO) CKD stages 2-4 were enrolled. The etiology of CKD and its comorbidities were recorded. Kaplan-Meier survival curves were used to analyze the time to progression of CKD.

RESULTS

Of the 131 patients enrolled, CKD stages 2, 3a, 3b, and 4 constituted 62 (47.3%), 17 (13%), 26 (19.8%), and 26 (19.8%), respectively. At the last follow-up [at median (IQR) 24 (12, 30) mo], the number of children in CKD stages 2, 3a, 3b, 4 and 5 were 48 (36.6%), 16 (12.2%), 23 (17.6%), 28 (21.4%), and 16 (12.2%), respectively. Etiologies of CKD included obstructive uropathy [48 (36.6%)], chronic glomerular disease [19 (14.5%)], reflux nephropathy [14 (10.7%)] and cystic renal disease [11 (8.3%)]. Comorbidities during follow-up included CKD-MBD [87 (66.4%)], metabolic acidosis [95 (72.5%)], hypertension [88 (67.1%)], growth retardation [69 (52.6%)], and anemia [63 (48.1%)]. The number of patients with metabolic acidosis, hypertension, MBD and anemia in CKD stage 2 were 27 (56%), 26 (54.2%), 24 (50%), 15 (30%), respectively. The median (IQR) rate of decline in eGFR was 3.3 (2, 4.6) mL/min/1.73 m²/y. On multivariable analysis, proteinuria [hazard ratio 3.5 (95% CI 1.4, 8.8) p = 0.01] and hyperphosphatemia [hazard ratio 2.2 (95% CI 1.1, 4.3) p = 0.03] were significant predictors for progression of CKD.

CONCLUSIONS

Even the earlier stages of CKD had significant comorbidities. The median decline in eGFR was 3.3 mL/min/1.73 m²/y. Proteinuria and hyperphosphatemia were the risk factors for progression of CKD.

Paediatric nephrology in under-resourced areas

BACKGROUND

Nearly 50% of the world population and 60% of children aged 0 to 14 years live in low- or lower-middle-income countries. Paediatric nephrology (PN) in these countries is not a priority for allocation of limited health resources. This article explores advancements made and persisting limitations in providing optimal PN services to children in such under-resourced areas (URA).

METHODS

Medline, PubMed and Google Scholar online databases were searched for articles pertaining to PN disease epidemiology, outcome, availability of services and infrastructure in URA. The ISN and IPNA offices were contacted for data, and two online questionnaire surveys of IPNA membership performed. Regional IPNA members were contacted for further detailed information.

RESULTS

There is a scarcity of published data from URA; where available, prevalence of PN diseases, managements and outcomes are often reported to be different from high income regions. Deficiencies in human resources, fluoroscopy, nuclear imaging, immunofluorescence, electron microscopy and genetic studies were identified. Several drugs and maintenance kidney replacement therapy are inaccessible to the majority of patients. Despite these issues, regional efforts with support from international bodies have led to significant advances in PN services and infrastructure in many URA.

CONCLUSIONS

Equitable distribution and affordability of PN services remain major challenges in URA. The drive towards acquisition of regional data, advocacy to local government and non-government agencies and partnership with international support bodies needs to be continued. The aim is to optimise and achieve global parity in PN training, investigations and treatments, initially focusing on preventable and reversible conditions.

Health and Dental Insurance and Health Care Utilization Among Children, Adolescents, and Young Adults With CKD: Findings From the CKiD Cohort Study

Rationale & Objective

To understand the association between health and dental insurance status and health and dental care utilization, and their relationship with disease severity in a population with childhood-onset chronic kidney disease (CKD).

Study Design

Observational cohort study.

Settings & Participants

Nine hundred fifty-three participants contributing 4,369 person-visits (unit of analysis) in the United States enrolled in the Chronic Kidney Disease in Children (CKiD) Study from 2005 to 2019.

Exposures

Health insurance (private vs public vs none) and dental insurance (presence vs absence) self-reported at annual visits.

Outcomes

Self-reported suboptimal health care utilization in the past year, defined separately as not visiting a private physician, visiting the emergency room, visiting the emergency room at least twice, being hospitalized, and self-reported suboptimal dental care utilization over the past year, defined as not receiving dental care.

Analytical Approach

Repeated measures Poisson regression models were fit to estimate and compare utilization by insurance type and disease severity at the prior visit. Additional unadjusted and adjusted models were fit, as well as models including interactions between insurance and Black race, maternal education, and income.

Results

Those with public health insurance were more likely to report suboptimal health care utilization across the CKD severity spectrum, and lack of dental insurance was strongly associated with lack of dental care. These relationships varied depending on strata of socioeconomic status and race but the effect measure modification was not significant.

Limitations

Details of insurance coverage were unavailable; reasons for emergency care or type of private physician visited were unknown.

Conclusions

Pediatric nephrology programs may consider interventions to help direct supportive resources to families with public insurance who are at higher risk for suboptimal utilization of care. Insurance providers should identify areas to expand access for families of children with CKD.

Sex and gender differences in chronic kidney disease and access to care around the globe

The difference between sex, the biological construct, and gender, the social construct, may be most evident in settings of vulnerability. Globally, chronic kidney disease is more prevalent among women, but the prevalence of end-stage kidney failure, and especially receipt of kidney replacement therapy, is higher in men. These differences likely reflect a combination of physiological and social/structural risk factors that independently modulate kidney disease and/or its progression. The distribution of the most common risk factors such as hypertension and obesity differ between men and women and may impact disease risk differentially. Social and structural gender-related inequities remain stark across the globe. More women live in poverty, receive less education, and are more dependent on others for health care decision making, but men may have a higher risk of injury, occupational exposures, and less access to screening, prevention, and primary care. In this article, we explore how social determinants of health affect kidney disease risk and access to care differentially across genders, and differently across the globe. We also describe specific challenges experienced by boys and girls with kidney disease, how culture and geography may impact kidney care in places where resources are particularly limited such as sub-Saharan Africa, and give examples of social and structural circumstances that place young men and women at high risk of kidney disease in Mexico and Central America, illustrated by case vignettes. The coronavirus disease-2019 pandemic has raised awareness of pervasive gender-based inequities within all societies. This applies to kidney disease and is not new. The nephrology community must add its voice to the calls for action, for a more just society overall, and for the recognition of the roles of sex and gender as modulators of kidney disease risk and access to care.

Adverse Consequences of Chronic Kidney Disease on Bone Health in Children

Chronic kidney disease (CKD) mineral bone disorder has long-term effects on skeletal integrity and growth. Abnormalities in serum markers of mineral metabolism are evident early in pediatric CKD. Bone deformities, poor linear growth, and high rates of fractures are common in children with CKD. Newer imaging modalities such as high-resolution peripheral quantitative computed tomography shows promise in assessing bone mineral density more comprehensively and predicting incident fractures. A lack of large-scale studies that provide a comprehensive assessment of bone histology and correlations with serum biomarkers has contributed to the absence of evidence-based guidelines and suboptimal management of CKD mineral bone disorder in children with CKD.

Dialysis Outcomes for Children With Lupus Nephritis Compared to Children With Other Forms of Nephritis: A Retrospective Cohort Study

RATIONALE & OBJECTIVE

Children with lupus nephritis (LN) are at high risk of developing kidney failure requiring initiation of kidney replacement therapy. This study compared outcomes among children with LN on dialysis with children with non-lupus glomerular disease and investigated risk factors for adverse outcomes among children with LN on dialysis.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Children and adolescents aged 6-20 years with LN (n = 231) and non-lupus glomerular disease (n = 1,726) who initiated maintenance dialysis 1991-2018 and were enrolled in the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) registry.

EXPOSURE

Lupus nephritis.

OUTCOME

Hospitalization, mortality, and time to transplant.

ANALYTICAL APPROACH

Contingency tables were used to compare hospitalizations, and multivariable cause-specific hazards models were used to compare rates of death and transplantation in children with LN compared with those with non-lupus glomerular disease. Using data from children with LN, multivariable logistic regression models were fit to evaluate the risk factors for hospitalization, and multivariable Cox regression models were fit to evaluate factors associated with kidney transplantation.

RESULTS

Children with LN were more likely to be hospitalized in the first year after dialysis initiation (63.3% vs 48.6%, P < 0.001) and were less likely to receive a kidney transplant in the first 3 years after dialysis initiation (year 0-1: adjusted hazard ratio [AHR], 0.36 [95% CI, 0.23-0.57], P < 0.001; year 1-3: AHR, 0.73 [95% CI, 0.54-0.98], P = 0.04). Anemia was associated with hospitalization after dialysis initiation (adjusted OR, 4.44 [95% CI, 1.44-13.66], P = 0.01). Non-White race was associated with a lower rate of kidney transplantation (AHR, 0.47 [95% CI, 0.27-0.82], P = 0.01). LN was not associated with death while on dialysis (AHR, 1.21 [95% CI, 0.47-3.11], P = 0.7).

LIMITATIONS

The NAPRTCS registry does not collect information on lupus disease activity or medication doses and has limited data on medication use.

CONCLUSIONS

Children and adolescents with LN on dialysis are at higher risk for adverse outcomes including hospitalization and lower rates of kidney transplantation compared with children with non-lupus glomerular disease receiving maintenance dialysis.

Reducing the burden of cardiovascular disease in children with chronic kidney disease: prevention vs. damage limitation

Cardiovascular disease (CVD) is a life-limiting condition in patients with chronic kidney disease (CKD) and is rapidly progressive, especially in those with stage 5 CKD and on dialysis. Cardiovascular mortality, although reducing, remains at least 30 times higher than in the general pediatric population. The American Heart Association guidelines for cardiovascular risk reduction in high-risk pediatric patients has stratified pediatric CKD patients in the "high risk" category for the development of CVD, with associated pathological and/or clinical evidence for manifest coronary disease before 30 years of age. While improving patient survival is a key priority, other patient-related outcomes, such as psychosocial development, quality of life and growth are of major importance to children and their caregivers. Once vascular damage or calcification has developed, there are no data to suggest that they can be reversed. Treatments such as intensified dialysis and transplantation may attenuate the progression of subclinical cardiovascular disease, but no treatment to date has shown that the inexorable progression of CVD in CKD can be reversed. Thus, our management must focus on early diagnosis and robust preventative strategies to give our patients the best chance of optimal cardiovascular health and survival. In this review, the pathophysiology and importance of preventing the development of CVD in CKD is discussed.

Alcohol, cigarette, e-cigarette and marijuana use among adolescents and young adults with chronic kidney disease in North America

PURPOSE

This study aimed to describe substance use (SU) among adolescents and young adults (AYA) with chronic kidney disease, compare these findings with the general population, and identify associated risk factors.

METHODS

708 AYA participants contributing 2475 person-visits from the Chronic Kidney Disease in Children Study were used to estimate prevalence rates of past year and 30-day alcohol, cigarette, e-cigarette and marijuana use, and were compared with national surveys. Repeated measures logistic regression estimated the association between SU and participant characteristics.

RESULTS

There was nearly no SU among those 12 to 14 years, but use increased with age, and past year alcohol use was about 80% for those greater than or equal to 22 years. Rates of use among males were constant or increased with age, while rates of use among females were lower after age 22 compared to ages 18 to 22. Associated risk factors included non-Black and non-Hispanic identity, older age, and worse disease severity. Participants were less likely to use substances compared to the general population, especially those 14-18 years.

CONCLUSIONS

SU was less common in AYA with chronic kidney disease than the general population, but differences were attenuated among those greater than or equal to 18 years. Ages 12-14 appear to be the ideal time for prevention efforts. As the landscape of e-cigarette and marijuana policies change, these results underscore the need to understand how similar high-risk populations engage in SU.

Chronic kidney disease impacts health-related quality of life of children in Uganda, East Africa

BACKGROUND

Limited data exist about causes of chronic kidney disease (CKD) and impact on health-related quality of life (HRQoL) in African children. We evaluated types of kidney disease in Ugandan children 0-18 years and compared HRQoL in children with CKD or with benign or resolving kidney disease (non-CKD) to assess predictors of HRQoL.

METHODS

Demographic, socioeconomic, and clinical data were obtained for this cross-sectional study. Pediatric Quality of Life Core Scale™ (PedsQL) was used to survey 4 domains and overall HRQoL. CKD and non-CKD scores were compared using unpaired t test. HRQoL predictors were evaluated using linear and logistic regression analyses.

RESULTS

One hundred forty-nine children (71 CKD, 78 non-CKD; median age 9 years; male 63%) had the following primary diseases: nephrotic syndrome (56%), congenital anomalies of the urinary tract (CAKUT) (19%), glomerulonephritis (17%), and other (8%). CAKUT was the predominant etiology (39%) for CKD; 63% had advanced stages 3b-5. Overall HRQoL scores were significantly lower for CKD (57 vs. 86 by child report, p < 0.001; 63 vs. 86 by parent proxy report, p < 0.001). Predictors of lower HRQoL were advanced CKD stages 3b-5, primary caregiver non-parent, vitamin D deficiency, and anemia.

CONCLUSION

Like other parts of the world, CAKUT was the main cause of CKD. Most CKD children presented at late CKD stages 3b-5. Compared with non-CKD, HRQoL in CKD was much lower; only two-thirds attended school. Vitamin D deficiency and anemia were potentially modifiable predictors of low HRQoL. Interventions with vitamin D, iron, and erythropoietin-stimulating agents might lead to improved HRQoL.

Chronic Kidney Disease in Adolescents after Surgery for Congenital Heart Disease

BACKGROUND

The onset of chronic kidney disease (CKD) is an important prognostic factor in young adults with congenital heart disease (CHD). Although it is likely that CKD is manifest early in CHD patients, the prevalence among adolescents is still unknown. The National Kidney Foundation's Kidney Disease Improving Global Outcomes guidelines 2012 recommend new equations for the estimated glomerular filtration rate (eGFR) and highlight the importance of albuminuria for CKD screening. The objective of the present study was to estimate the prevalence of CKD in CHD adolescents.

METHODS

This observational cross-sectional study included 115 patients aged 10-18 years attending the cardiologic outpatient clinic at our institution as a follow-up after cardiac surgery in infancy related to various CHDs. CKD assessment used the CKD criteria 2012, including eGFR equations based on serum creatinine and cystatin C, and measurement of albuminuria.

RESULTS

No patient had an eGFR <60 mL min-1 1.73 m-2. However, 28.7% of all patients (95% CI 20.7-37.9) had eGFRbetween 60 and 89 mL min-1 1.73 m-2 when estimated by the bedside Schwartz creatinine-based equation,and 17.4% (95% CI 11.2-24.1) had eGFRbetween 60 and 89 mL min-1 1.73 m-2 when estimated by the Zappitelli equation, combining creatinine and cystatin C. Of all patients, 20.0% (95% CI 12.1-26.7) had orthostatic proteinuria, and none had persistent albuminuria.

CONCLUSIONS

There was no evidence of CKD in the present population aged 10-18 years. The significance of an eGFR between 60 and 90 mL min-1 1.73 m-2 is not concordant for this age range and requires further investigations.

Developing Consensus-Based Outcome Domains for Trials in Children and Adolescents With CKD: An International Delphi Survey

RATIONALE & OBJECTIVE

The inconsistency in outcomes reported and lack of patient-reported outcomes across trials in children with chronic kidney disease (CKD) limits shared decision making. As part of the Standardized Outcomes in Nephrology (SONG)-Kids initiative, we aimed to generate a consensus-based prioritized list of critically important outcomes to be reported in all trials in children with CKD.

STUDY DESIGN

An online 2-round Delphi survey in English, French, and Hindi languages.

SETTINGS & PARTICIPANTS

Patients (aged 8-21 years), caregivers/family, and health care professionals (HCPs) rated the importance of outcomes using a 9-point Likert scale (7-9 indicating critical importance) and completed a Best-Worst Scale.

ANALYTICAL APPROACH

We assessed the absolute and relative importance of outcomes. Comments were analyzed thematically.

RESULTS

557 participants (72 [13%] patients, 132 [24%] caregivers, and 353 [63%] HCPs) from 48 countries completed round 1 and 312 (56%) participants (28 [40%] patients, 64 [46%] caregivers, and 220 [56%] HCPs) completed round 2. Five outcomes were common in the top 10 for each group: mortality, kidney function, life participation, blood pressure, and infection. Caregivers and HCPs rated cardiovascular disease higher than patients. Patients gave lower ratings to all outcomes compared with caregivers/HCPs except they rated life participation (round 2 mean difference, 0.1), academic performance (0.1), mobility (0.4), and ability to travel (0.4) higher than caregivers and rated ability to travel (0.4) higher than HCPs. We identified 3 themes: alleviating disease and treatment burden, focusing on the whole child, and resolving fluctuating and conflicting goals.

LIMITATIONS

Most participants completed the survey in English.

CONCLUSIONS

Mortality, life participation, kidney function, and blood pressure were consistently highly prioritized by patients, caregivers, and HCPs. Patients gave higher priority to some lifestyle-related outcomes compared with caregivers/HCPs. Establishing critically important outcomes for all trials in children with CKD may improve consistent reporting of survival, kidney health, and clinical and life impact outcomes that are meaningful for decision making.

Association of Time-Varying Blood Pressure With Chronic Kidney Disease Progression in Children

IMPORTANCE

Optimal blood pressure (BP) management in children with chronic kidney disease (CKD) slows progression to end-stage renal disease. Studies often base progression risk on a single baseline BP measurement, which may underestimate risk.

OBJECTIVE

To determine whether time-varying BP measurements are associated with a higher risk of progression of CKD than baseline BP measurements.

DESIGN, SETTING, AND PARTICIPANTS

The ongoing longitudinal, prospective cohort study Chronic Kidney Disease in Children (CKID) recruited children from January 19, 2005, through March 19, 2014, from pediatric nephrology centers across North America, with data collected at annual study visits. Participants included children aged 1 to 16 years with a diagnosis of CKD and a glomerular filtration rate (GFR) of 30 to 90 mL/min/1.73 m2. Data were analyzed from February 11, 2005, through February 13, 2018.

EXPOSURES

Office BP measurement classified as less than 50th percentile, 50th to less than 90th percentile, or at least 90th percentile. Blood pressure categories were treated as time fixed (baseline) or time varying (updated at each visit) in models.

MAIN OUTCOMES AND MEASURES

A composite renal outcome (50% GFR reduction from baseline, estimated GFR less than 15 mL/min/1.73 m2, or dialysis or transplant). Pooled logistic models using inverse probability weighting estimated the hazard odds ratio (HOR) of the composite outcome associated with each BP category stratified by CKD diagnosis.

RESULTS

A total of 844 children (524 [62.1%] male; median age, 11 [interquartile range, 8-15] years; 151 [17.9%] black; 580 [68.7%] with nonglomerular CKD; and 264 [31.3%] with glomerular CKD) with complete baseline data and median follow-up of 4 (interquartile range, 2-6) years were included. One hundred ninety-six participants with nonglomerular diagnoses (33.8%) and 99 with glomerular diagnoses (37.5%) reached the composite outcome. Baseline systolic BP in at least the 90th percentile was associated with a higher risk of the composite outcome (HOR for nonglomerular disease, 1.58 [95% CI, 1.07-2.32]; HOR for glomerular disease, 2.85 [95% CI, 1.64-4.94]) compared with baseline systolic BP in less than the 50th percentile. Time-fixed estimates were substantially lower compared with time-varying systolic BP percentile categories (HOR among those with nonglomerular CKD, 3.75 [95% CI, 2.53-5.57]; HOR among those with glomerular diagnoses, 5.96 [95% CI, 3.37-10.54]) comparing those at or above the 90th percentile vs below the 50th percentile. Adjusted models (adjusted for proteinuria and use of antihypertensives) attenuated the risk in nonglomerular CKD (adjusted HOR for baseline measurement, 1.52 [95% CI, 0.98-2.36]; adjusted HOR for time-varying measurement, 2.25 [95% CI, 1.36-3.72]) and in glomerular CKD (adjusted HOR for baseline, 0.97 [95% CI, 0.39-2.36]; adjusted HOR for time-varying measurement, 1.41 [95% CI, 0.65-3.03]). Similar results were observed for diastolic BP.

CONCLUSIONS AND RELEVANCE

Among children with nonglomerular CKD included in this study, elevated time-varying BP measurements were associated with a greater risk of CKD progression compared with baseline BP measurement. This finding suggests that previous studies using only baseline BP likely underestimated the association between BP and CKD progression.

Development of a risk score for earlier diagnosis of chronic kidney disease in children

Objective

To develop a clinical score for the early identification of chronic kidney disease (CKD) in children and adolescents. The early diagnosis of CKD in childhood allows the adoption of measures to slow the progression of the disease, thereby reducing morbidity and mortality. Nevertheless, the diagnosis is often made too late for proper patient management.

Study design

We preformed a case-control study of a multicenter Brazilian sample of 752 pediatric patients; the study cases (n = 376) were CKD patients with a median estimated GFR of 37 (IQR = 22 to 57) ml/min/1.73 m². The control group (n = 376) comprised age-, gender- and center-matched children who were followed for nonrenal diseases. Potential risk factors were investigated through a standard questionnaire that included symptoms, medical history, and a clinical examination. Two multivariable models (A and B) were fitted to assess predictors of the diagnosis of CKD.

Results

In model A, 9 variables were associated with CKD diagnosis: antenatal ultrasound with urinary malformation, recurrent urinary tract infection, polyuria, abnormal urine stream, nocturia, growth curve flattening, history of hypertension, foamy urine and edema (c-statistic = 0.938). Model B had the same variables as model A, except for the addition of the history of admission during the neonatal period and the exclusion of antenatal ultrasound variables (c-statistic = 0.927).

Conclusions

The present scores may serve as a warning sign for CKD diagnosis in children among professionals working in the primary care setting where the symptoms associated with a risk of CKD may be overlooked.

Prospective cohort analyzing risk factors for chronic kidney disease progression in children

OBJECTIVE

To identify risk factors for chronic kidney disease progression in Brazilian children and to evaluate the interactions between factors.

METHODS

This was a multicenter prospective cohort in São Paulo, involving 209 children with CKD stages 3-4. The study outcome included: (a) death, (b) start of kidney replacement therapy, (c) eGFR decrease >50% during the followup. Thirteen risk factors were tested using univariate regression models, followed by multivariable Cox regression models. The terms of interaction between the variables showing significant association with the outcome were then introduced to the model.

RESULTS

After a median follow-up of 2.5 years (IQR=1.4-3.0), the outcome occurred in 44 cases (21%): 22 started dialysis, 12 had >50% eGFR decrease, seven underwent transplantation, and three died. Advanced CKD stage at onset (HR=2.16, CI=1.14-4.09), nephrotic proteinuria (HR=2.89, CI=1.49-5.62), age (HR=1.10, CI=1.01-1.17), systolic blood pressure Z score (HR=1.36, CI=1.08-1.70), and anemia (HR=2.60, CI=1.41-4.77) were associated with the outcome. An interaction between anemia and nephrotic proteinuria at V1 (HR=0.25, CI=0.06-1.00) was detected.

CONCLUSIONS

As the first CKD cohort in the southern hemisphere, this study supports the main factors reported in developed countries with regards to CKD progression, affirming the potential role of treatments to slow CKD evolution. The detected interaction suggests that anemia may be more deleterious for CKD progression in patients without proteinuria and should be further studied.

Trends in Albuminuria and GFR Among Adolescents in the United States, 1988-2014

RATIONALE & OBJECTIVE

Albuminuria and low estimated glomerular filtration rate (eGFR) define chronic kidney disease in adults and youth. Different from adults, the burden of abnormal kidney markers among youth in the general United States population is largely unknown.

STUDY DESIGN

Serial cross-sectional national surveys.

SETTING & PARTICIPANTS

Adolescents aged 12 to 18 years participating in the National Health and Nutrition Examination Surveys 1988 to 2014. Surveys were grouped into three 6-year periods.

PREDICTORS

Demographic and clinical determinants of kidney markers.

OUTCOME

Prevalence and trends in persistent albuminuria, low (< 60mL/min/1.73m²) and reduced (< 90mL/min/1.73m²) eGFRs.

ANALYTICAL APPROACH

Outcomes defined as persistent albumin-creatinine ratio ≥ 30mg/g (persistent albuminuria), eGFR < 90mL/min/1.73m² (reduced kidney function), and eGFR < 60mL/min/1.73m² (low kidney function). Multiple imputation analysis was used to estimate missing follow-up values of albuminuria.

RESULTS

Prevalences of persistent albuminuria were 3.64% (95% CI, 1.82%-5.46%) in 1988-1994 and 3.29% (95% CI, 1.94%-4.63%) in 2009-2014 (adjusted prevalence ratio, 0.93; 95% CI, 0.53-1.62; P=0.8 for trend). Prevalences of reduced eGFR were 31.46% (95% CI, 28.42%-34.67%) and 34.58% (95% CI, 32.07%-37.18%), respectively (adjusted prevalence ratio, 1.21; 95% CI, 1.00-1.46; P < 0.001 for trend). Prevalences of low eGFR were 0.32% (95% CI, 0.12%-0.84%) in 1988-1994 and 0.91% (95% CI, 0.58%-1.42%) in 2009-2014 (adjusted prevalence ratio, 3.10; 95% CI, 1.10-9.01; P = 0.09 for trend). Prevalences of albuminuria and/or low eGFR remained at 4.0% in 1988-1994 and 2009-2014 (adjusted prevalence ratio, 1.06; 95% CI, 0.64-1.77; P = 0.8 for trend).

LIMITATIONS

Persistent albuminuria data were based on imputed values (for second assessment of albuminuria) in 91% of participants; lack of second eGFR assessment to confirm sustained reduction in kidney function.

CONCLUSIONS

Albuminuria prevalence has not changed significantly in the US adolescent population between 1988 and 2014. Prevalences of both reduced and low eGFRs were higher in the most recent study period; however, < 1% of adolescents had low eGFRs.

Genetic basis of human congenital anomalies of the kidney and urinary tract

The clinical spectrum of congenital anomalies of the kidney and urinary tract (CAKUT) encompasses a common birth defect in humans that has significant impact on long-term patient survival. Overall, data indicate that approximately 20% of patients may have a genetic disorder that is usually not detected based on standard clinical evaluation, implicating many different mutational mechanisms and pathogenic pathways. In particular, 10% to 15% of CAKUT patients harbor an unsuspected genomic disorder that increases risk of neurocognitive impairment and whose early recognition can impact clinical care. The emergence of high-throughput genomic technologies is expected to provide insight into the common and rare genetic determinants of diseases and offer opportunities for early diagnosis with genetic testing.

Chronic Kidney Disease (CKD): An Observational Study of Etiology, Severity and Burden of Comorbidities

OBJECTIVES

To study the etiology and burden of comorbidities across stages of chronic kidney disease (CKD).

METHODS

Children, 2-16 y of age with CKD Stages II- IV were recruited over 12 mo. The etiology, clinical presentation and severity of complications were studied.

RESULTS

Among 78 children [Stage II (n = 21), Stage III (n = 26), Stage IV (n = 31)], congenital anomalies of the kidney and urinary tract (CAKUT) was the commonest etiology and 28 were newly diagnosed in Stage III /IV. High prevalence of comorbidities was observed with growth retardation (65%), hypertension (59%), hyperphosphatemia (32%), vitamin D deficiency (92%), dyslipidemia (64%), left ventricular hypertrophy (45%) and hyperparathyroidism (56%). While most comorbidities correlated with the estimated glomerular filtration rate and severity of CKD, hypertension, vitamin D deficiency and cardiovascular morbidity were prevalent even in early stages.

CONCLUSIONS

CAKUT was the commonest cause of CKD. Late detection and high prevalence of comorbidities even in early stages of CKD were observed.

Health-related quality of life of children with pre-dialysis chronic kidney disease

BACKGROUND

The goal of this study was to evaluate the quality of life (QOL) of Asian children with pre-dialysis chronic kidney disease (CKD) and to reveal the factors influencing the QOL of children with CKD.

METHODS

We performed a cross-sectional study of the PedsQL 4.0 Generic Core Scale Module in the KNOW-PedCKD (KoreaN cohort study for Outcome in patients with Pediatric Chronic Kidney Disease) cohort, and compared the child self-reported and parent proxy-reported QOL of the pediatric cohort. From 2011 through 2016, a total of 376 children with CKD were enrolled after informed consent was obtained from parents or caregivers in seven pediatric nephrology centers.

RESULTS

In parent proxy-reports, male patients had a better QOL than female patients in the Physical Functioning category. In child self-reports, male patients had better QOL than female patients in the Physical, Emotional, and School Functioning categories. According to CKD stage, there were significant differences in the QOL score in all categories of parent proxy-reports, and patients with higher CKD stage (lower glomerular filtration rate) had a worse QOL. Growth parameters showed a significantly positive correlation with the QOL score in all categories.

CONCLUSIONS

The QOL of children with predialysis CKD is affected by various factors, including sex, glomerular filtration rate (GFR), socio-economic status, existence of co-morbidities, anemia, growth retardation, and behavioral disorders. To improve their QOL, it is important to objectively understand the respective effects of these factors and attempt early intervention.

Female Adolescents with Chronic or End-Stage Kidney Disease and Strategies for their Care

The prevalence of chronic or end-stage kidney disease in pediatric girls is lower than in boys, however, girls have unique morbidities that can have great effect on their quality of life. For female adolescents, creatinine excretion peaks at approximately 14 years of age and is significantly less than males, owing to lower muscle mass. Females have higher nitric oxide activity, and estrogens may contribute to lower blood pressure. Females excrete less growth hormone during the prepubertal and pubertal years. Females between the ages of 8 and 10 years show increased levels of parathyroid hormone and vitamin D, however, female adolescents with chronic kidney disease have less estrogen and loss of the luteinizing hormone pulsatile pattern. These biological, hormonal, and physical changes affect the psychosocial aspects of female adolescents with chronic kidney disease/end-stage kidney disease, and they must learn to manage their health to achieve good outcomes. Patients and their parents must learn disease management through a customized health care transition preparation in both the pediatric- and adult-focused settings. Clinical strategies are suggested for the care of these special patients.

Chronic kidney disease and sports participation by children and adolescents

Individuals suffering from chronic kidney disease (CKD) deal with major morbidity and mortality including poor exercise tolerance. A variety of factors including anemia, poor muscle mass, cardiovascular changes and limited physical activity contribute to exercise intolerance. Studies suggest that early initiation of aerobic and resistance training improves the muscle function, ability to tolerate exercise and quality of life in CKD patients. A thorough medical examination and exercise testing are recommended before initiating an exercise regimen in individuals with CKD. Though current recommendations suggest a qualified approval to contact sports in patients with solitary kidney, a proper risk assessment and counselling must be provided detailing all the risks involved. Special care must be taken to avoid infection or damage to the peritoneal dialysis catheter and hemodialysis vascular access sites. Collision sports should be avoided in individuals with kidney transplant, ectopic kidney or with other urological abnormalities (severe hydronephrosis or ureteropelvic junction obstruction) with high risk of injury.

Preemptive kidney transplantation is associated with survival benefits among pediatric patients with end-stage renal disease

Kidney transplantation is the preferred treatment for pediatric end-stage renal disease (ESRD). Preemptive transplantation avoids the increased morbidity and mortality of dialysis. Yet, previous studies have not demonstrated significant graft or patient survival benefits for children undergoing transplantation preemptively versus nonpreemptively. These previous studies were limited by small samples sizes and low rates of adverse events. Here we compared graft failure and mortality rates using Kaplan-Meier methods and Cox regression among a large national cohort of children with ESRD undergoing preemptive versus nonpreemptive kidney transplantation between 2000 and 2012. Among 7527 pediatric kidney transplant recipients in the United States Renal Data System, 1668 underwent preemptive transplantation. Over a median 4.8 years follow-up, 1314 experienced graft failure, and over a median 5.2 years of follow-up, 334 died. Dialysis exposure versus preemptive transplantation conferred a higher risk of graft failure (hazard ratio 1.32; 95% confidence interval: 1.10-1.56) and a higher risk of death (hazard ratio 1.69; 95% confidence interval: 1.22-2.33) in multivariable analysis. Compared with children undergoing preemptive transplantation, children on dialysis for >1 year had a 52% higher risk of graft failure and those on dialysis >18 months had an 89% higher risk of death, regardless of donor source. Thus, preemptive transplantation is associated with substantial benefits in allograft and patient survival among children with ESRD, particularly when compared with children who receive dialysis for >1 year. These findings support policies to promote early access to transplantation and avoidance of dialysis for children with ESRD whenever feasible.

Neurocognitive functions of pediatric kidney transplant recipients

BACKGROUND

End-stage renal disease (ESRD) in children is associated with impaired neurocognitive function and development. However, data on factors associated with neurocognitive dysfunctions in children with kidney transplants are limited.

METHODS

We conducted a cross-sectional analysis comparing cognitive functions (using the Woodcock-Johnson International Edition, WJIE) in 35 kidney transplant and 35 healthy control children. Data on laboratory measurements, comorbidities, and social characteristics were collected.

RESULTS

Transplant children had significantly worse scores on the intelligence quotient (IQ) test compared with controls [Full Scale IQ score 85 (26) vs 107 (10), p <0.001]. Lower maternal education level was significantly associated with lower WJIE cognitive test scores; however, no association was found between laboratory values and WJIE scores. Among children with kidney transplants, those with medical comorbid conditions had significantly lower Verbal Ability and Full Scale IQ scores. Earlier age of dialysis onset and a longer total time on dialysis (>9 months) were associated with lower test scores. Age-standardized duration of hospitalization was inversely correlated with IQ (r = -0.46, p <0.01) and was an independent significant predictor (Beta = -0.38, p = 0.02) of IQ scores in transplanted children.

CONCLUSIONS

Child kidney transplant recipients have neurocognitive function impairments that are associated with markers of socioeconomic status (SES) and factors related to disease severity.

17-Year-Old Boy with Renal Failure and the Highest Reported Creatinine in Pediatric Literature

The prevalence of chronic kidney disease (CKD) is on the rise and constitutes a major health burden across the world. Clinical presentations in early CKD are usually subtle. Awareness of the risk factors for CKD is important for early diagnosis and treatment to slow the progression of disease. We present a case report of a 17-year-old African American male who presented in a life threatening hypertensive emergency with renal failure and the highest reported serum creatinine in a pediatric patient. A brief discussion on CKD criteria, complications, and potential red flags for screening strategies is provided.

Growth impairment in children with pre-dialysis chronic kidney disease in Japan

BACKGROUND

Growth impairment is a major complication of chronic kidney disease (CKD) in children. However, no cohort studies have examined the growth of Asian children with pre-dialysis CKD.

METHODS

We sent cross-sectional surveys to 113 Japanese medical institutions that were treating 447 children with CKD stages 3-5 in 2010 and 2011. Of 447 children included in our survey conducted in 2010, height and CKD stage were evaluable for 297 children in 2011, and height standard deviation score (height SDS) was calculated in these children.

RESULTS

Height SDS decreased with increasing CKD stage (P < 0.001) in boys and girls. Height SDS also decreased significantly with increasing CKD stage among patients with congenital anomalies of the kidney and urinary tract (P < 0.001). Risk factors for growth impairment included CKD stages 4 and 5 (relative to stage 3), being small-for-date, and asphyxia at birth. Among children with a height SDS ≤-2.0, growth hormone was used in 19.5, 31.0, and 25.0 % of children with CKD stages 3, 4, and 5, respectively.

CONCLUSIONS

This prospective cohort study revealed marked growth impairment in Japanese children with CKD stages 3-5 relative to healthy children. CKD-related risk factors for growth impairment included advanced CKD (stages 4 and 5), being small-for-date, and asphyxia at birth. Growth hormone was infrequently used in this cohort of children with pre-dialysis CKD.

Anthropometric and biochemical profile of children and adolescents with chronic kidney disease in a predialysis pediatric interdisciplinary program

This is longitudinal retrospective observational cohort study that evaluated anthropometric and biochemical variables of children and adolescents admitted to a Predialysis Interdisciplinary Management Program (PDIMP) responsible for the follow-up of children and adolescents at stages 2 to 4 of chronic kidney disease (CKD) at a tertiary center. One hundred thirty-eight patients with CKD on predialysis treatment with median age at admission of 9 years and the median follow-up time of 5 years were evaluated. Seventy-four (53%) had CKD stage 3 at admission and 70 (51%) reached CKD stage 5 at the end of the follow-up. There was no significant difference between the mean initial and final hemoglobin and serum albumin. However, the final serum bicarbonate presented a significant improvement. Analyses stratified according to clinical variables of interest showed a significant improvement in body mass index (BMI) Z score, especially in the subgroup of children admitted under two years of age. In relation to stature-for-age Z score, data show a significant improvement in stature SD at the end of the study. In conclusion, the present study showed improvement of nutritional status of CKD patients and that the deterioration of renal function was not correlated with BMI-for-age Z score.

Progression to end-stage kidney disease in Japanese children with chronic kidney disease: results of a nationwide prospective cohort study

BACKGROUND

The risk of progressing to end-stage kidney disease (ESKD) and factors associated with progression in children with chronic kidney disease (CKD) are unclear, especially in Asian children.

METHODS

We started a nationwide, prospective cohort study of 447 Japanese children with pre-dialysis CKD in 2010, with follow-up in 2011. Progression to ESKD was analyzed by Kaplan-Meier analysis according to CKD stage. Cox regression analysis was used to identify risk factors for progression.

RESULTS

Data were analyzed for 429/447 children. Five patients died, of which four died before progression to ESKD. Fifty-two patients progressed to ESKD (median follow-up 1.49 years), including 9/315 patients with stage 3 CKD, 29/107 with Stage 4 CKD and 14/25 with Stage 5 CKD. One-year renal survival rates were 98.3, 80.0 and 40.9%, for Stages 3, 4 and 5 CKD, respectively. Risk factors for progression to ESKD included CKD stage [versus Stage 3; Stage 4: hazard ratio (HR) 11.12, 95% confidence interval (CI) 4.22-29.28, P < 0.001; Stage 5: HR 26.95, 95% CI 7.71-94.17, P < 0.001], heavy proteinuria (>2.0 g/g urine creatinine; HR 7.56, 95% CI 3.22-17.77, P < 0.001) and age ( < 2 years: HR 9.06; 95% CI 2.29-35.84, P = 0.002; after starting puberty: HR 4.88; 95% CI 1.85-12.85, P = 0.001).

CONCLUSIONS

In this cohort, 12.5% of children with pre-dialysis CKD progressed to ESKD with a median-follow-up of 1.49 years. Children with advanced (Stage 4/5) CKD were particularly likely to progress. To our knowledge, this is the first, nationwide, prospective cohort study of children with pre-dialysis CKD in Asia.

A predictive model of progression of CKD to ESRD in a predialysis pediatric interdisciplinary program

BACKGROUND AND OBJECTIVES

The incidence of ESRD in children has increased over the last two decades. Nevertheless, there are still limited data on risk factors related to the emergence of ESRD among patients with CKD. The aim of this study was to develop a model of prediction of ESRD in children and adolescents with CKD (stages 2-4) enrolled in a predialysis interdisciplinary management program.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective cohort study, 147 patients with CKD admitted from 1990 to 2008 were systematically followed up at a tertiary pediatric nephrology unit for a median of about 4.5 years. The primary outcome was the progression to CKD stage 5. A predictive model was developed using Cox proportional hazards model and evaluated by c statistics.

RESULTS

The median renal survival was estimated at 98.7 months (95% confidence interval [95% CI], 68.7 to 129.6 months). The probability of reaching CKD stage 5 was estimated as 52% in 10 years. The most accurate model included eGFR, proteinuria at admission, and primary renal disease. Risk score ranged from 0 to 13 points (median, 4 points). The accuracy of the score applied to the sample was high, with c statistics of 0.865 (95% CI, 0.80 to 0.93) and 0.837 (95% CI, 0.76 to 0.91) at follow-up of 2 and 5 years, respectively. By survival analysis, it was estimated that at 10 years after admission, the probability of renal survival was about 63% for patients in the low-risk group and 43% for the medium-risk group; all patients assigned to the high-risk group had CKD stage 5 (P<0.001).

CONCLUSION

The predictive model of progression of CKD might contribute to early identification of a subgroup of patients at high risk for accelerated renal failure.

Perception of health-related quality of life in children with chronic kidney disease by the patients and their caregivers: multicentre national study results

OBJECTIVE

The aim of the study was to analyse the health-related quality of life (HRQoL) in Polish children with chronic kidney disease (CKD) dependant on the CKD stage, treatment modality and selected social life elements in families of the patients. Furthermore, potential differences between self-report and parent/proxy reports and the factors influencing them were assessed.

METHODS

A total of 203 CKD children (on haemodialysis (HD), peritoneal dialysis (PD) and conservative treatment (CT)) and their 388 parent/proxies were enrolled into a cross-sectional national study. The demographic and social data were evaluated. We used the Paediatric Quality of Life Inventory 4.0 Generic Core Scales to assess the HRQoL in children.

RESULTS

Health-related quality of life scores for all CKD groups were significantly lower in all domains compared with population norms, the lowest one being in the HD group. In CT children, HRQoL did not depend on the CKD stage. Both parents assessed the HRQoL of their children differently depending on their involvement in the care. There are differences between the HRQoL scores of the children and their parents.

CONCLUSION

The HRQoL in children with CKD is lower than in healthy children. This is already observed in the early stages of the disease. The disease itself influences the child's mental state. Children on HD require special support on account of the lowest demonstrated overall HRQoL. Children's lower rating of the quality of life observed by their parents may render the patients unmotivated and adversely affect their adjustment to life in later years. It may also create conflicts between the parents and the children.

Blood lead level and measured glomerular filtration rate in children with chronic kidney disease

BACKGROUND

The role of environmental exposure to lead as a risk factor for chronic kidney disease (CKD) and its progression remains controversial, and most studies have been limited by a lack of direct glomerular filtration rate (GFR) measurement.

OBJECTIVE

We evaluated the association between lead exposure and GFR in children with CKD.

METHODS

In this cross-sectional study, we examined the association between blood lead levels (BLLs) and GFR measured by the plasma disappearance of iohexol among 391 participants in the Chronic Kidney Disease in Children (CKiD) prospective cohort study.

RESULTS

Median BLL and GFR were 1.2 µg/dL and 44.4 mL/min per 1.73 m2, respectively. The average percent change in GFR for each 1-µg/dL increase in BLL was -2.1 (95% CI: -6.0, 1.8). In analyses stratified by CKD diagnosis, the association between BLL and GFR was stronger among children with glomerular disease underlying CKD; in this group, each 1-µg/dL increase in BLL was associated with a -12.1 (95% CI: -22.2, -1.9) percent change in GFR. In analyses stratified by anemia status, each 1-µg/dL increase in BLL among those with and without anemia was associated with a -0.3 (95% CI: -7.2, 6.6) and -4.6 (95% CI: -8.9, -0.3) percent change in GFR, respectively.

CONCLUSIONS

There was no significant association between BLL and directly measured GFR in this relatively large cohort of children with CKD, although associations were observed in some subgroups. Longitudinal analyses are needed to examine the temporal relationship between lead and GFR decline, and to further examine the impact of underlying cause of CKD and anemia/hemoglobin status among patients with CKD.

Cardiorenal syndrome is present in human fetuses with severe, isolated urinary tract malformations

OBJECTIVE

We analyzed the association between renal and cardiovascular parameters in fetuses with isolated severe urinary tract malformations.

METHODS

39 fetuses at a mean gestational age of 23.6 weeks with nephropathies or urinary tract malformations and markedly impaired or absent renal function were prospectively examined. Fetal echocardiography was performed, and thicknesses of the interventricular septum, and left and right ventricular wall were measured. Blood flow velocity waveforms of the umbilical artery, middle cerebral artery, and ductus venosus were obtained by color Doppler ultrasound. Concentrations of circulating n-terminal pro-B-type natriuretic peptide (nt-proBNP), cystatin C, ß2-microglobulin, and hemoglobin were determined from fetal blood samples.

RESULTS

Malformations included 21 cases of obstructive uropathy, 10 fetuses with bilateral nephropathy, and 8 cases of bilateral renal agenesis. Marked biventricular myocardial hypertrophy was present in all cases. The ratio between measured and gestational age-adjusted normal values was 2.01 (interventricular septum), 1.85, and 1.78 (right and left ventricular wall, respectively). Compared to controls, levels of circulating nt-proBNP were significantly increased (median (IQR) 5035 ng/L (5936 ng/L) vs. 1874 ng/L (1092 ng/L); p<0.001). Cystatin C and ß2-microglobulin concentrations were elevated as follows (mean ± SD) 1.85±0.391 mg/L and 8.44±2.423 mg/L, respectively (normal range 1.66±0.202 mg/L and 4.25±0.734 mg/L, respectively). No correlation was detected between cardiovascular parameters and urinary tract morphology and function. Despite increased levels of nt-proBNP cardiovascular function was preserved, with normal fetal Doppler indices in 90.2% of cases.

CONCLUSION

Urinary tract malformations resulting in severe renal impairment are associated with biventricular myocardial hypertrophy and elevated concentrations of circulating nt-proBNP during fetal life. Cardiovascular findings do not correlate with kidney function or morphology.

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

BACKGROUND

Nephrotic syndrome is one of the most commonly diagnosed kidney diseases in childhood and its progressive forms can lead to chronic kidney disease (CKD) and/or end-stage renal disease (ESRD). There have been few longitudinal studies among a multi-ethnic cohort to determine potential risk factors influencing disease susceptibility, treatment response, and progression of nephrotic syndrome. Temporal relationships cannot be studied through cross-sectional study design. Understanding the interaction between various factors is critical to developing new strategies for treating children with kidney disease. We present the rationale and the study design of a longitudinal cohort study of children with nephrotic syndrome, the Insight into Nephrotic Syndrome: Investigating Genes, Health and Therapeutics (INSIGHT) study. The specific aims are to determine: 1) socio-demographic, environmental, and genetic factors that influence disease susceptibility; 2) rates of steroid treatment resistance and steroid treatment dependence, and identify factors that may modify treatment response; 3) clinical and genetic factors that influence disease susceptibility and progression to CKD and ESRD; and 4) the interaction between the course of illness and socio-demographic, environmental, and clinical risk factors.

METHODS/DESIGN

INSIGHT is a disease-based observational longitudinal cohort study of children with nephrotic syndrome. At baseline, participants complete questionnaires and provide biological specimen samples (blood, urine, and toenail clippings). Follow-up questionnaires and repeat biological specimen collections are performed annually for up to five years.

DISCUSSION

The proposed cohort will provide the structure to test various risk factors predicting or influencing disease susceptibility, treatment response, and progression to CKD among children with nephrotic syndrome.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01605266.