Age- and sex-dependent clinical equations to estimate glomerular filtration rates in children and young adults with chronic kidney disease

Acute kidney injury in children with haematological malignancy: a territory-wide study

BACKGROUND

In onco-nephrology, data on acute kidney injury (AKI) among children with haematological malignancies are scarce.

METHODS

A retrospective cohort study of all patients in Hong Kong diagnosed with haematological malignancies from 2019 to 2021 before 18 years of age, was conducted to investigate the epidemiology, risk factors and clinical outcomes of AKI during the first year of treatment. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria.

RESULTS

We included 130 children with haematological malignancy at median age of 9.4 years (IQR, 3.9-14.1). Of these patients, 55.4% were acute lymphoblastic leukemia (ALL), 26.9% were lymphoma and 17.7% were acute myeloid leukemia (AML). Thirty-five patients (26.9%) developed 41 AKI episodes during the first year of diagnosis, corresponding to 32 episodes per 100-patient-year. A total of 56.1% and 29.2% of the AKI episodes occurred during induction and consolidation chemotherapy respectively. Septic shock (n = 12, 29.2%) was the leading cause of AKI; 21 episodes (51.2%) were stage 3 AKI; 12 episodes (29.3%) were stage 2 AKI; and 6 patients required continuous kidney replacement therapies. Tumor lysis syndrome and impaired baseline kidney function were significantly associated with AKI on multivariate analysis (P = 0.01). History of AKI was associated with chemotherapy postponement (37.1% vs. 16.8%, P = 0.01), worse 12-month patient survival (77.1% vs. 94.7%, log rank P = 0.002) and lower disease remission rate at 12-month (68.6% vs. 88.4%, P = 0.007), compared to patients without AKI.

CONCLUSION

AKI is a common complication during treatment of haematological malignancies which is associated with worse treatment outcomes. A regular and dedicated surveillance program for at-risk patients should be studied in children with haematological malignancies for prevention and early detection of AKI. A higher resolution version of the Graphical abstract is available as Supplementary information.

Association of clinical characteristics with urine uromodulin in children with chronic kidney disease

BACKGROUND

Uromodulin is the most abundant protein in the urine of healthy adults, and higher urine concentrations mark better tubular health. Greater kidney size and function are predictors of higher uromodulin levels in adults. Urine uromodulin has not yet been studied in children with chronic kidney disease (CKD). Thus, we sought to determine the relationship between age and kidney function with urine uromodulin levels in children with CKD.

METHODS

In the CKD in Children (CKiD) cohort, we utilized multivariable linear regression to evaluate the relationship of age and eGFR with urine uromodulin levels. The primary outcome was uromodulin indexed to urine creatinine (Umod/Cr, mg/g), which was log2-transformed given its skewed distribution.

RESULTS

Among 677 CKiD participants, the median age was 11.8 years (8.2-15.3), the median eGFR was 49 ml/min/1.73 m2 (37-63), the etiology of CKD was glomerular disease in 31%, and the median Umod/Cr level was 0.114 mg/g (0.045-0.226). In the multivariable models, each one-year older age was associated with 0.18 (12%) lower log2(Umod/Cr) and 0.20 (13%) lower log2(Umod/Cr) among those with non-glomerular and glomerular disease, respectively (p < 0.001). However, we did not find a statistically significant association between eGFR and Umod/Cr in either participants with non-glomerular or glomerular disease (p = 0.13 and p = 0.58, respectively).

CONCLUSIONS

Among children with CKD, older age is significantly associated with lower Umod/Cr, independent of eGFR. Further studies are needed to comprehensively evaluate age-specific reference ranges for urine uromodulin and to evaluate the longitudinal relationship of uromodulin with both age and eGFR in children with CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Development of an adaptive clinical web-based prediction tool for kidney replacement therapy in children with chronic kidney disease

Clinicians need improved prediction models to estimate time to kidney replacement therapy (KRT) for children with chronic kidney disease (CKD). Here, we aimed to develop and validate a prediction tool based on common clinical variables for time to KRT in children using statistical learning methods and design a corresponding online calculator for clinical use. Among 890 children with CKD in the Chronic Kidney Disease in Children (CKiD) study, 172 variables related to sociodemographics, kidney/cardiovascular health, and therapy use, including longitudinal changes over one year were evaluated as candidate predictors in a random survival forest for time to KRT. An elementary model was specified with diagnosis, estimated glomerular filtration rate and proteinuria as predictors and then random survival forest identified nine additional candidate predictors for further evaluation. Best subset selection using these nine additional candidate predictors yielded an enriched model additionally based on blood pressure, change in estimated glomerular filtration rate over one year, anemia, albumin, chloride and bicarbonate. Four additional partially enriched models were constructed for clinical situations with incomplete data. Models performed well in cross-validation, and the elementary model was then externally validated using data from a European pediatric CKD cohort. A corresponding user-friendly online tool was developed for clinicians. Thus, our clinical prediction tool for time to KRT in children was developed in a large, representative pediatric CKD cohort with an exhaustive evaluation of potential predictors and supervised statistical learning methods. While our models performed well internally and externally, further external validation of enriched models is needed.

Acute kidney injury following treatment with CD19-specific CAR T-cell therapy in children, adolescent and young adult patients with B-cell acute lymphoblastic leukemia

CD19-specific chimeric antigen receptor (CAR) T-cell therapy has shown promising disease responses in patients with high-risk B-cell malignancies. Treatment with CD19-CAR T-cell therapy is also associated with the risk of morbidity and mortality, primarily related to immune-mediated complications (cytokine release syndrome [CRS] and neurotoxicity [NTX]), infections, and end-organ dysfunction. Despite these well-described systemic toxicities, the incidence of post-CAR T-cell therapy acute kidney injury (AKI) in the children, adolescent and young adult (CAYA) patient population is largely unreported. The objectives of this study were to determine the incidence of AKI in CAYA patients with high-risk B-cell malignancies treated with CD19-CAR T-cell therapy, evaluate potential risk factors for developing AKI, and determine patterns of kidney function recovery. In this retrospective analysis of 34 CAYA patients treated with CD19-CAR T-cell at a single institution, we found a cumulative incidence of any grade AKI by day 30 post-infusion of 20% (n=7), with 4 cases being severe AKI (Stage 2-3) and one patient requiring kidney replacement therapy. All episodes of AKI developed within the first 14 days after receiving CAR T-cell therapy and 50% of patients with AKI recovered kidney function to baseline within 30 days post-infusion. No evaluated pre-treatment risk factors were associated with the development of subsequent AKI; there was an association between AKI and CRS and NTX. We conclude that the risk of developing AKI following CD19-CAR T-cell therapy is highest early post-infusion, with most cases of AKI being severe. Although most patients with AKI in our cohort had recovery of kidney function, frequent monitoring to facilitate early recognition and subsequent management of kidney complications after CD19-CAR T-cell therapy may reduce the severity of AKI in the CAYA patient population.

Chronic kidney disease in children: an update

Chronic kidney disease (CKD) is a major healthcare issue worldwide. However, the prevalence of pediatric CKD has never been systematically assessed and consistent information is lacking in this population. The current definition of CKD is based on glomerular filtration rate (GFR) and the extent of albuminuria. Given the physiological age-related modification of GFR in the first years of life, the definition of CKD is challenging per se in the pediatric population, resulting in high risk of underdiagnosis in this population, treatment delays and untailored clinical management. The advent and spreading of massive-parallel sequencing technology has prompted a profound revision of the epidemiology and the causes of CKD in children, supporting the hypothesis that CKD is much more frequent than currently reported in children and adolescents. This acquired knowledge will eventually converge in the identification of the molecular pathways and cellular response to damage, with new specific therapeutic targets to control disease progression and clinical features of children with CKD. In this review, we will focus on recent innovations in the field of pediatric CKD and in particular those where advances in knowledge have become available in the last years, with the aim of providing a new perspective on CKD in children and adolescents.

The Impact of Pediatric CKD on Educational and Employment Outcomes

Key Points

This study evaluates educational and employment outcomes in patients with pediatric kidney disease and assesses predictors of educational attainment and employment in young adulthood. Despite high rates of high school graduation, nearly 20% of patients with CKD are unemployed or receiving disability at long-term follow-up.

Background

Pediatric patients with CKD are at risk for neurocognitive deficits and academic underachievement. This population may be at risk for lower educational attainment and higher rates of unemployment; however, published data have focused on patients with advanced CKD and exist in isolation from assessment of neurocognition and kidney function.

Methods

Data from the CKD in Children (CKiD) cohort study were used to characterize educational attainment and employment status in young adults with CKD. We used ratings of executive function as a predictor of future educational attainment and employment status. Linear regression models predicted the highest grade level completed. Logistic regression models predicted unemployment.

Results

A total of 296 CKiD participants aged 18 years or older had available educational data. In total, 220 of 296 had employment data. By age 22 years, 97% had completed high school and 48% completed 2+ years of college. Among those reporting employment status, 58% were part-time or full-time employed, 22% were nonworking students, and 20% were unemployed and/or receiving disability. In adjusted models, lower kidney function (P = 0.02), worse executive function (P = 0.02), and poor performance on achievement testing (P = 0.004) predicted lower grade level completed relative to expectation for age.

Conclusions

CKiD study patients appear to have a better high school graduation rates (97%) than the adjusted national high school graduation rate (86%). Conversely, roughly 20% of participants were unemployed or receiving disability at study follow-up. Tailored interventions may benefit patients with CKD with lower kidney function and/or executive function deficits to optimize educational/employment outcomes in adulthood.

A novel acute kidney injury scoring system for renal and clinical outcomes in pediatric heart transplant patients

BACKGROUND

The development of acute kidney injury (AKI) has been associated with worse outcomes in children after heart transplantation. Our study compares the application of a cumulative six-point Kidney Diseases Improving Global Outcomes (KDIGO) AKI scoring system, utilizing both creatinine and urine output criteria that we term as the AKI-6 criteria, to traditional AKI staging as a predictor for clinical and renal outcomes in the pediatric heart transplant recipients.

METHODS

We conducted a retrospective single-center chart review on 155 pediatric patients who underwent heart transplantation from May 2014 to December 2021. The primary independent variable was the presence of severe AKI. Severe AKI by KDIGO was defined as Stage ≥2, whereas severe AKI by AKI-6 was defined as cumulative scores ≥4 or Stage 3 AKI based on either KDIGO criterion alone. Primary outcomes included actuarial survival and renal dysfunction by 1-year post-transplant, defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2 .

RESULTS

In total, 140 (90%) patients developed AKI; 98 (63%) patients developed severe AKI by KDIGO, and 60 (39%) by AKI-6. Severe AKI by AKI-6 was associated with worse actuarial survival following heart transplantation compared with KDIGO (p = 0.01). Of the 143 patients with 1-year creatinine data, 6 (11%) patients out of 54 with severe AKI by AKI-6 had evidence of renal dysfunction (p = 0.01), compared with 6 (7%) patients out of 88 by KDIGO (p = 0.3).

CONCLUSIONS

AKI-6 scoring provides greater prognostic utility for actuarial survival and renal dysfunction by 1-year post-heart transplantation in pediatric patients than traditional KDIGO staging.

Estimated pediatric glomerular filtration rate presentation improves the detection rate of kidney impairment in children

BACKGROUND

Accurate interpretation of everyday laboratory work is crucial for the early detection of impaired kidney function. Bedside estimation of glomerular filtration rate (eGFR) in children is based on serum creatinine standardized for body mass, most commonly using the revised Schwartz equation using height. This study evaluates how data presentation affects the correct assessment of children's kidney function.

METHODS

In this survey-based study, 121 physicians treating children routinely in a tertiary hospital answered 11 clinical questions requiring assessment of kidney function based on serum creatinine with general (adult) or pediatric normal serum creatinine ranges, or by presented eGFR. The demographic data of the participants were collected.

RESULTS

Presenting eGFR values rather than the customary presentation of serum creatinine and anthropometric parameters more than quadrupled the number of physicians who accurately estimated pediatric kidney function; 38.8% of physicians correctly assessed kidney function when presented with eGFR values but misinterpreted it when equivalent creatinine values were presented (p < 0.001). Seniority, specialty, and self-reported frequency of pediatric kidney function assessment did not affect the interpretation.

CONCLUSIONS

Presenting physicians with calculated eGFR can dramatically improve the ability of the medical team to assess kidney function correctly in children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Reduced kidney function and hypertension in adolescents with low birth weight, NHANES 1999-2016

BACKGROUND

Chronic kidney disease (CKD) is a major health problem, and the risk of CKD and hypertension in children born low birth weight (LBW) is under-recognized. We hypothesized that children born with LBW would have a higher prevalence of reduced kidney function and hypertension.

METHODS

Using the National Health and Nutrition Examination Survey (NHANES), we conducted a cross-sectional study to evaluate whether LBW (< 2500 g), very low birth weight (VLBW < 1500 g), and large birth weight (BW) (> 4000 g) were associated with kidney disease using 4 different estimating equations. We used the Counahan-Barratt, updated Schwartz, CKiD-U25, and full age spectrum creatinine-based GFR estimating equations to evaluate associations between a history of LBW/VLBW/large BW and reduced kidney function (eGFR < 90 mL/min/1.73 m2) in children. We also assessed blood pressure (BP) using the old and new pediatric hypertension guidelines.

RESULTS

Our analysis included 6336 children (age 12-15 years) in NHANES representing over 13 million US individuals. Using the updated Schwartz, the prevalence of reduced kidney function was 30.1% (25.2-35.6) for children born with LBW compared to 22.4% (20.5-24.3) in children with normal BW. Equations yielded different estimates of prevalence of reduced kidney function in LBW from 21.5% for Counahan-Barratt to 35.4% for CKiD-U25. Compared to those with normal BW, participants with LBW and VLBW had a 7.2 and 10.3% higher prevalence of elevated BP and a 2.4 and 14.6% higher prevalence of hypertension, respectively.

CONCLUSIONS

Children born with LBW are at higher risk of reduced kidney function and hypertension than previously described. A higher resolution version of the Graphical abstract is available as Supplementary information.

Hyperkalemia in pediatric chronic kidney disease

BACKGROUND

While hyperkalemia is well described in adult chronic kidney disease (CKD), large studies evaluating potassium trends and risk factors for hyperkalemia in pediatric CKD are lacking. This study aimed to characterize hyperkalemia prevalence and risk factors in pediatric CKD.

METHODS

Cross-sectional analysis of Chronic Kidney Disease in Children (CKiD) study data evaluated median potassium levels and percentage of visits with hyperkalemia (K ≥5.5 mmoL/L) in relation to demographics, CKD stage, etiology, proteinuria, and acid-base status. Multiple logistic regression was used to identify risk factors for hyperkalemia.

RESULTS

One thousand and fifty CKiD participants with 5183 visits were included (mean age 13.1 years, 62.7% male, 32.9% self-identifying as African American or Hispanic). A percentage of 76.6% had non-glomerular disease, 18.7% had CKD stage 4/5, 25.8% had low CO2, and 54.2% were receiving ACEi/ARB therapy. Unadjusted analysis identified a median serum potassium level of 4.5 mmol/L (IQR 4.1-5.0, p <0.001) and hyperkalemia in 6.6% of participants with CKD stage 4/5. Hyperkalemia was present in 14.3% of visits with CKD stage 4/5 and glomerular disease. Hyperkalemia was associated with low CO2 (OR 7.72, 95%CI 3.05-19.54), CKD stage 4/5 (OR 9.17, 95%CI 4.02-20.89), and use of ACEi/ARB therapy (OR 2.14, 95%CI 1.36-3.37). Those with non-glomerular disease were less frequently hyperkalemic (OR 0.52, 95%CI 0.34-0.80). Age, sex, and race/ethnicity were not associated with hyperkalemia.

CONCLUSIONS

Hyperkalemia was observed more frequently in children with advanced stage CKD, glomerular disease, low CO2, and ACEi/ARB use. These data can help clinicians identify high-risk patients who may benefit from earlier initiation of potassium-lowering therapies. A higher resolution version of the Graphical abstract is available as Supplementary information.

Data quality control in longitudinal epidemiologic studies: conditional studentized residuals from linear mixed effects models for outlier detection in the setting of pediatric chronic kidney disease

PURPOSE

Quality control in longitudinal cohort studies is critical for valid epidemiologic inference. Conditional studentized residuals (CSRs) derived from linear mixed effects models offer efficient individual-specific quality control. We present the utility of CSRs for outlier detection in an applied example using data from the Chronic Kidney Disease in Children cohort.

METHODS

Longitudinal linear mixed effects models with glomerular filtration rate (GFR) as the outcome were fit for observations prior to kidney replacement therapy, stratified by nonglomerular or glomerular diagnosis, and for a subset after receiving a kidney transplant. For each model, CSRs were calculated and values ≥±5 were considered potential outliers for further investigation.

RESULTS

A total of 1096 participants contributed 6881 annual measures of GFR across the two diagnostic groups and after transplant. In all models, the fixed effects captured progressive GFR decline. CSRs provided measures of individual-level deviations from the modeled trajectories (random + fixed effects) and were easily visualized in longitudinal plots. A total of 38 potential outliers from 32 participants were detected and further investigated for quality control.

CONCLUSIONS

This example demonstrated how longitudinal models can provide CSRs to detect individual-specific outliers. CSRs should be considered as part of quality control for longitudinal epidemiologic studies.

Low agreement between various eGFR formulae in pediatric and young adult ADPKD patients

BACKGROUND

Young autosomal dominant polycystic kidney disease (ADPKD) patients are becoming the new target population for the development of new treatment options. Determination of a reliable equation for estimated glomerular filtration rate (eGFR) from early stages is needed with the promising potential interventional therapies.

METHODS

Prospective and longitudinal study on a cohort of 68 genotyped ADPKD patients (age range 0-23 years) with long-term follow-up. Commonly used equations for eGFR were compared for their relative performance.

RESULTS

The revised Schwartz formula (CKiD) showed a highly significant decline in eGFR with aging (- 3.31 mL/min/1.73 m2/year, P < 0.0001). The recently updated equation by the Schwartz group (CKiDU25) showed a smaller (- 0.90 mL/min/1.73 m2/year) but significant (P = 0.001) decline in eGFR with aging and also showed a significant sex difference (P < 0.0001), not observed by the other equations. In contrast, the full age spectrum (FAS) equations (FAS-SCr, FAS-CysC, and the combined) showed no age and sex dependency. The prevalence of hyperfiltration is highly dependent on the formula used, and the highest prevalence was observed with the CKiD Equation (35%).

CONCLUSIONS

The most widely used methods to calculate eGFR in ADPKD children (CKiD and CKiDU25 equations) were associated with unexpected age or sex differences. The FAS equations were age- and sex-independent in our cohort. Hence, the switch from the CKiD to CKD-EPI equation at the transition from pediatric to adult care causes implausible jumps in eGFR, which could be misinterpreted. Having reliable methods to calculate eGFR is indispensable for clinical follow-up and clinical trials. A higher resolution version of the Graphical abstract is available as Supplementary information.

Glomerular hyperfiltration: part 1 - defining the threshold - is the sky the limit?

Glomerular hyperfiltration (GHF) is an increase in single-nephron glomerular filtration rate (GFR) that occurs in both physiological states and pathological states. Whole-kidney GHF is often used as a surrogate for single-nephron hyperfiltration since determining single-nephron GFR is impossible in routine clinical care. A clear definition (read threshold) of GHF is lacking. The aim of the first part of this review was to find evidence for defining the threshold for GHF, based on literature review, including systematic reviews and meta-analysis data, with both measured and estimated GFR. The consensus pediatric threshold for GHF as obtained from reviews, measured and estimated GFR studies, can reliably be set to 135 mL/min/1.73 m2 for children aged > 2 years. Diagnosing GHF from SCr-based estimated GFR is not reliable in subjects with reduced muscle mass. In these cases, it could be of interest to confirm the state of GHF using cystatin C-based eGFR, or preferably, by measured GFR, using methods that are accurate in the high GFR-range.

Imaging fibrosis in pediatric kidney transplantation: A pilot study

BACKGROUND

Noninvasive alternatives to biopsy for assessment of interstitial fibrosis and tubular atrophy (IFTA), the major determinant of kidney transplant failure, remain profoundly limited. Elastography is a noninvasive technique that propagates shear waves across tissues to measure their stiffness. We aimed to test utility of elastography for early detection of IFTA in pediatric kidney allografts.

METHODS

We compared ultrasound (USE) and MR elastography (MRE) stiffness measurements, performed on pediatric transplant recipients referred for clinically indicated biopsies, and healthy controls.

RESULTS

Ten transplant recipients (median age 16 years) and eight controls (median age 16.5 years) were enrolled. Three transplant recipients had "stable" allografts and seven had Banff Grade 1 IFTA. Median time from transplantation to biopsy was 12 months. Mean estimated glomerular filtration rate was 61.5 mL/min/1.73m2 by creatinine-cystatin-C CKiD equation at time of biopsy. Mean stiffness, calculated through one-way ANOVA, was higher for IFTA allografts (23.4 kPa USE/5.6 kPa MRE) than stable allografts (13.7 kPa USE/4.4 kPa MRE) and controls (9.1 kPa USE/3.6 kPa MRE). Pearson's coefficient between USE and MRE stiffness values was strong (r = .97). AUC for fibrosis prediction in transplanted kidneys was high for both modalities (0.91 USE and 0.89 MRE), although statistically nonsignificant (p > .05). Stiffness cut-off values for USE and MRE were 13.8 kPa and 4.6 kPa, respectively. Both values yielded a sensitivity of 100% but USE specificity (72%) was slightly higher than MRE (67%).

CONCLUSION

Elastography shows potential for detection of low-grade IFTA in allografts although a larger sample is imperative for clinical validation.

Estimation of glomerular filtration rate in a pediatric population using non-contrast kidney phase contrast magnetic resonance imaging

BACKGROUND

Glomerular filtration rate (GFR) is a key measure of kidney function but often inaccurately ascertained by serum creatinine and cystatin C in pediatrics. In this pilot trial, we evaluated the relationship between GFR calculated by using phase-contrast MRI (PC-MRI) biomarkers and GFR by 125I-iothalamate clearance in youth undergoing bone marrow transplantation (BMT).

METHODS

A total of twenty-one pediatric BMT candidates (8-21 years of age) were recruited for a research kidney PC-MRI. After completion of 125I-iothalamate clearance, same-day PC-MRI measurements were completed of the kidney circulation without a gadolinium-based contrast agent. MRI included a non-contrast balanced-SSFP-triggered angiography to position ECG-gated breath-held 2D PC-MRI flow measurements (1.2 × 1.2 × 6 mm3). A multivariate model of MRI biomarkers estimating GFR (GFR-MRI) was selected using the elastic net approach.

RESULTS

The GFR-MRI variables selected by elastic net included average heart rate during imaging (bpm), peak aorta flow below the kidney artery take-offs (ml/s), average kidney artery blood flow, average peak kidney vein blood flow, and average kidney vein blood flow (ml/s). The GFR-MRI model demonstrated strong agreement with GFR by 125I-iothalamate (R2 = 0.65), which was stronger than what was observed with eGFR by the full age spectrum and Chronic Kidney Disease in Children under 25 (CKiD U25) approaches.

CONCLUSION

In this pilot study, noninvasive GFR-MRI showed strong agreement with gold standard GFR in youth scheduled for BMT. Further work is needed to evaluate whether non-contrast GFR-MRI holds promise to become a superior alternative to eGFR and GFR by clearance techniques. A higher resolution version of the Graphical abstract is available as Supplementary information.

Timing of Kidney Replacement Therapy among Children and Young Adults

BACKGROUND

No randomized trials exist to guide the timing of the initiation of KRT in children. We sought to define trends and predictors of the eGFR at initiation of KRT, center-related clinical practice variation, and any association with patient survival.

METHODS

Children and young adults (1-25 years) commencing KRT (dialysis or kidney transplantation) between 1995 and 2018 were included using data from the Australia and New Zealand Dialysis and Transplant Registry. The associations between eGFR on commencing KRT and covariates were estimated using quantile regression. Cox regression was used to estimate the association between eGFR and patient survival. Logistic regression, categorizing eGFR about a value of 10 ml/min per 1.73 m 2 , was used in conjunction with a random effect by center to quantify clinical practice variation.

RESULTS

Overall, 2274 participants were included. The median eGFR at KRT initiation increased from 7 to 9 ml/min per 1.73 m 2 over the study period and the 90th centile from 11 to 17 ml/min per 1.73 m 2 . The effect of era on median eGFR was modified by modality, with a greater increase among those receiving a preemptive kidney transplant (1.0 ml/min per 1.73 m 2 per 5 years; 95% confidence interval [CI], 0.6 to 1.5) or peritoneal dialysis (0.7 ml/min per 1.73 m 2 per 5 years; 95% CI, 0.4 to 0.9) compared with hemodialysis (0.1 ml/min per 1.73 m 2 per 5 years; 95% CI, -0.1 to 0.3). There were 252 deaths (median follow-up 8.5 years, interquartile range 3.7-14.2) and no association between eGFR and survival (hazard ratio, 1.01 per ml/min per 1.73 m 2 ; 95% CI, 0.98 to 1.04). Center variation explained 6% of the total variance in the odds of initiating KRT earlier. This rose to over 10% when comparing pediatric centers alone.

CONCLUSIONS

Children and young adults progressively commenced KRT earlier. This change was more pronounced for children starting peritoneal dialysis or receiving a preemptive kidney transplant. Earlier initiation of KRT was not associated with any difference in patient survival. A substantial proportion of clinical practice variation was due to center variation alone.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_08_08_CJN0000000000000204.mp3.

Patient-Reported Outcomes Over 24 Months in Pediatric CKD: Findings From the MyKidneyHealth Cohort Study

RATIONALE & OBJECTIVE

The lived experience of children with chronic kidney disease (CKD) is poorly characterized. We examined the associations between patient-reported outcome (PRO) scores measuring their fatigue, sleep health, psychological distress, family relationships, and global health with clinical outcomes over time in children, adolescents, and younger adults with CKD and investigated how the PRO scores of this group compare with those of other children, adolescents, and younger adults.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

212 children, adolescentss, and adults aged 8 to 21 years with CKD and their parents recruited from 16 nephrology programs across North America.

PREDICTORS

CKD stage, disease etiology, and sociodemographic and clinical variables.

OUTCOME

PRO scores over 2 years.

ANALYTICAL APPROACH

We compared PRO scores in the CKD sample with a nationally representative general pediatric population (ages 8 to 17 years). Change of PROs over time and association of sociodemographic and clinical variables with PROs were assessed using multivariable regression models.

RESULTS

For all time points, 84% of the parents and 77% of the children, adolescents, and younger adults completed PRO surveys . The baseline PRO scores for the participants with CKD revealed a higher burden of fatigue, sleep-related impairment, psychological distress, impaired global health, and poorer family relationships compared with the general pediatric population, with median score differences≥1 SD for fatigue and global health. The baseline PRO scores did not differ by CKD stage or glomerular versus nonglomerular etiology. Over 2 years, PROs were stable with a<1-point annual change on average on each measure and intraclass correlation coefficients ranging from 0.53 to 0.79, indicating high stability. Hospitalization and parent-reported sleep problems were associated with worse fatigue, psychological health, and global health scores (all P<0.04).

LIMITATIONS

We were unable to assess responsiveness to change with dialysis or transplant.

CONCLUSIONS

Children with CKD experience a high yet stable burden of impairment across numerous PRO measures, especially fatigue and global health, independent of disease severity. These findings underscore the importance of assessing PROs, including fatigue and sleep measures, in this vulnerable population.

PLAIN-LANGUAGE SUMMARY

Children with chronic kidney disease (CKD) have many treatment demands and experience many systemic effects. How CKD impacts the daily life of a child is poorly understood. We surveyed 212 children, adolescents, and younger adults with CKD and their parents over 24 months to assess the participants' well-being over time. Among children, adolescents, and younger adults with CKD we found a very high and persistent burden of psychological distress that did not differ by degree of CKD or type of kidney disease. The participants with CKD endorsed greater impairment in fatigue and global health compared with healthy children, adolescents, and younger adults, and parent-reported sleep problems were associated with poorer patient-reported outcome (PRO) scores across all domains. These findings emphasize the importance of including PRO measures, including fatigue and sleep measures, into routine clinical care to optimize the lived experience of children with CKD.

NT-proBNP Reference Intervals in Healthy U.S. Children, Adolescents, and Adults

BACKGROUND

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a cardiac biomarker used in the clinical management of heart failure. We sought to create updated reference intervals for NT-proBNP for healthy US children, adolescents, and adults.

METHODS

We identified a population of healthy individuals using the 1999 to 2004 cycles of the National Health and Nutrition Examination Survey (NHANES). We measured serum NT-proBNP in 12 346 adults and 15 752 children and adolescents with the Elecsys NT-proBNP assay on the Roche e601 autoanalyzer. We compared 4 methods for reference interval calculation, and presented the final reference intervals using the robust method partitioned by age and sex categories.

RESULTS

NT-proBNP values were available for 1949 healthy adults and 5250 healthy children and adolescents. NT-proBNP concentrations in males and females varied according to age, being higher in early childhood, relatively lower in late adolescence, and highest through middle age and older age. Females tended to have higher NT-proBNP concentrations compared to men from late adolescence until middle age. The upper reference limit, or 97.5th percentile, for 50 to 59 year-old men was 225 ng/L (90% CI: 158 to 236), and for 50 to 59 year-old women, 292 ng/L (90% CI: 242 to 348).

CONCLUSIONS

Among healthy individuals, NT-proBNP concentrations varied greatly according age and sex. The reference intervals presented here should inform future clinical decision limits and suggest that age- and sex-specific intervals may be necessary to more precisely characterize risk.

Estimating the Glomerular Filtration Rate in Pediatric Patients With Neurogenic Bladder: A Comparison Between Creatinine- and Cystatin C-Equations

Background and objective Patients with neurogenic bladder (NB) are at a higher risk of developing chronic kidney disease (CKD). Due to their lower muscle mass, the estimated glomerular filtration rate (eGFR) based on creatinine (Cr) may be overestimated and delay the diagnosis of renal failure. This study compared eGFR calculated with different equations based on Cr and/or cystatin C (CysC) in children with NB, and the differences between patients with lower muscle mass (underdeveloped lower limbs) and those with independent gait (less muscle depletion). Methods We calculated the eGFR in pediatric patients with NB and CKD stages 1 and 2 by using the following equations: Chronic Kidney Disease in Children equation for serum creatinine (CKiD-Cr), CKiD-CysC, CKiD combined-Cr/CysC, Zappitelli-CysC, and Zappitelli combined-Cr/CysC. Results We evaluated a total of 47 patients, 74.5% with CKD stage 1, with a median age of 14.1 years. Of these participants, 59.6% had lipo/myelomeningocele. The CKiD-Cr and CysC-based equations led to significantly lower calculated eGFR ​​(p<0.05), specifically CKiD-CysC (p<0.001), Zappitelli-CysC (p<0.001), CKiD-Cr/CysC (p<0.001), and Zappitelli combined-Cr/CysC (p<0.05). When CKiD-CysC was used, 68% of the patients moved to a more advanced CKD stage. In patients without independent gait, with lower muscle mass (55.3%), the median eGFR calculated using the CKiD-Cr and CKiD combined-Cr/CysC equations was significantly higher (p<0.05). However, there were no differences between the two groups when using the other CysC-based equations. Conclusion In patients with NB and poor muscle mass, the CKiD-Cr equation may overestimate renal function. CysC-based equations seem more reliable in these patients, especially in those with greater muscular atrophy.

Urinary Metabolomic Profile of Youth at Risk of Chronic Kidney Disease in Nicaragua

Key Points

Urinary concentrations of glycine, a molecule associated with thermoregulation, were elevated among youth from a high-risk region for chronic kidney disease of non-traditional etiology (CKDnt). Urinary concentrations of pyruvate, citric acid, and inosine were lower among youth at higher risk of CKDnt, suggesting renal stress. Metabolomic analyses may shed light on early disease processes or profiles or risk in the context of CKDnt.

Background

CKD of a nontraditional etiology (CKDnt) is responsible for high mortality in Central America, although its causes remain unclear. Evidence of kidney dysfunction has been observed among youth, suggesting that early kidney damage contributing to CKDnt may initiate in childhood.

Methods

Urine specimens of young Nicaraguan participants 12–23 years without CKDnt (n =136) were analyzed by proton nuclear magnetic resonance spectroscopy for 50 metabolites associated with kidney dysfunction. Urinary metabolite levels were compared by, regional CKDnt prevalence, sex, age, and family history of CKDnt using supervised statistical methods and pathway analysis in MetaboAnalyst. Magnitude of associations and changes over time were assessed through multivariable linear regression.

Results

In adjusted analyses, glycine concentrations were higher among youth from high-risk regions (β =0.82, [95% confidence interval, 0.16 to 1.85]; P = 0.01). Pyruvate concentrations were lower among youth with low eGFR (β = −0.36 [95% confidence interval, −0.57 to −0.04]; P = 0.03), and concentrations of other citric acid cycle metabolites differed by key risk factors. Over four years, participants with low eGFR experienced greater declines in 1-methylnicotinamide and 2-oxoglutarate and greater increases in citrate and guanidinoacetate concentrations.

Conclusion

Urinary concentration of glycine, a molecule associated with thermoregulation and kidney function preservation, was higher among youth in high-risk CKDnt regions, suggestive of greater heat exposure or renal stress. Lower pyruvate concentrations were associated with low eGFR, and citric acid cycle metabolites, such as pyruvate, likely relate to mitochondrial respiration rates in the kidneys. Participants with low eGFR experienced longitudinal declines in concentrations of 1-methylnicotinamide, an anti-inflammatory metabolite associated with anti-fibrosis in tubule cells. These findings merit further consideration in research on the origins of CKDnt.

Understanding Similarities and Differences in CKD and Dialysis Care in Children and Adults

In lower-income settings there is often a dearth of resources and nephrologists, especially pediatric nephrologists, and individual physicians often find themselves caring for patients with chronic kidney diseases and end-stage kidney failure across the age spectrum. The management of such patients in high-income settings is relatively protocolized and permits high-volume services to run efficiently. The basic principles of managing chronic kidney disease and providing dialysis are similar for adults and children, however, given the differences in body size, causes of kidney failure, nutrition, and growth between children and adults with kidney diseases, nephrologists must understand the relevance of these differences, and have an approach to providing quality and safe dialysis to each group. Prevention, early diagnosis, and early intervention with simple therapeutic and lifestyle interventions are achievable goals to manage symptoms, complications, and reduce progression, or avoid kidney failure in children and adults. These strategies currently are easier to implement in higher-resource settings with robust health systems. In many low-resource settings, kidney diseases are only first diagnosed at end stage, and resources to pay out of pocket for appropriate care are lacking. Many barriers therefore exist in these settings, where specialist nephrology personnel may be least accessible. To improve management of patients at all ages, we highlight differences and similarities, and provide practical guidance on the management of children and adults with chronic kidney disease and kidney failure. It is important that children are managed with a view to optimizing growth and well-being and maximizing future options (eg, maintaining vein health and optimizing cardiovascular risk), and that adults are managed with attention paid to quality of life and optimization of physical health.

Longitudinal Estimated Glomerular Filtration Rate Trajectories in Children with Type 1 Diabetes

Although children with type 1 diabetes (T1D) are at risk for developing diabetic kidney disease (DKD), clinical practice guidelines do not uniformly recommend routine serum creatinine (SCr) monitoring, and data describing changes in renal function from diagnosis are lacking. As part of a quality improvement initiative, the Diabetes Clinic at British Columbia Children's Hospital in Vancouver, Canada, implemented routine serum SCr monitoring. This study describes estimated glomerular filtration rate (eGFR) trajectories and prevalence of decreased eGFR, hypertension, and albuminuria and their relationship to patterns of nephrology referral in a cohort of children aged ≤18 years (n = 307) with T1D recruited between December 2016 and February 2019. Annualized eGFR (ml/min/1.73 m2 per year) was calculated using the CKiD U25 formula and categorized as declining (<-3), stable (-3 to +3), and inclining (>+3). eGFR was categorized as normal (≥90), mildly decreased (60 to <90), and chronic kidney disease (CKD, <60). In this cohort, 54% were male; the median age at diagnosis and duration of T1D was 6.2 years and 6.9 years, respectively. Over a median follow-up of 2.3 years, declining, stable, and inclining trajectories were observed in 33%, 32%, and 35%, respectively. During their follow-up, 32% had mildly decreased eGFR, elevated blood pressures (≥90th percentile), and/or abnormal urine albumin-creatinine ratios (≥2 mg/mmol), with <10% referred for nephrology assessment. Twenty-three percent of subjects had an eGFR <90; this subgroup was more highly represented in the declining trajectory group (vs. stable and inclining). Logistic regression analysis found female sex and higher baseline eGFR to be associated with a declining eGFR trajectory. In conclusion, these data challenge the commonly held paradigm that renal function remains stable in childhood T1D and supports systematic monitoring of renal function in children with T1D, as well as collaboration across disciplines, particularly endocrinology and nephrology, to provide evidence-based individualized care.

Review of acute kidney injury and progression to chronic kidney disease in pediatric patients undergoing hematopoietic cell transplant

While acute kidney injury (AKI) after hematopoietic cell transplant (HCT) has been well-described in pediatric patients, literature regarding the long term renal consequences of HCT-related AKI, the development of chronic kidney disease (CKD), and CKD care in pediatric patients post-HCT is limited. CKD affects almost 50% of patients after HCT with multifactorial etiology including infection, nephrotoxic medications, transplant-associated thrombotic microangiopathy, graft-versus-host disease, and sinusoidal obstruction syndrome. As renal function declines in CKD, eventually progressing to end stage kidney disease (ESKD), mortality increases and is more than 80% among patients requiring dialysis. Using society guidelines and current literature, this review summarizes definitions and etiologies of and management strategies among patients with AKI and CKD post-HCT with an emphasis on albuminuria, hypertension, nutrition, metabolic acidosis, anemia, and mineral bone disease. The goal of this review is to aid early identification and intervention in patients with renal dysfunction prior to development of ESKD, and to discuss ESKD and renal transplant in these patients post-HCT.

Outcomes in infants with unprovoked venous thromboembolism: A retrospective cohort study

Background

Although children aged <1 year have a relatively high rate of venous thromboembolism (VTE) compared to older children, most have additional prothrombotic risk factors. Unprovoked VTE is rare, and little is known about this population, particularly the risk of recurrent VTE.

Objectives

We aimed to determine the rate of recurrent VTE in infants with prior unprovoked VTE and evaluate long-term, end-organ outcomes for infants with renal and intracranial vein thrombosis.

Methods

Infants <1 year of age with an unprovoked VTE between 2003 and 2021 at a single institution were included. Time to recurrent event and anticoagulation duration were summarized using the Kaplan-Meier estimator. Neurologic outcomes were summarized with the pediatric stroke outcome measure for infants with cerebral sinovenous, medullary, or cortical vein thrombosis. Kidney outcomes were summarized with estimated glomerular filtration rates for infants with renal vein thrombosis. Anticoagulation was summarized.

Results

Forty infants with intracranial, renal, portal, and extremity VTE met the inclusion criteria and were followed for a median of 4.7 years (IQR, 2.1-8.5). Most VTE events occurred during the first month of life. There was 1 recurrent event in 237 person-years of follow-up (incidence rate, 4 per 1000 [95% CI, 0.6-29.9] person-years). In outpatient follow-up, 40% of infants with intracranial thrombosis met criteria for moderate or severe neurologic outcomes and two-thirds of infants with a prior renal vein thrombosis had abnormal kidney function (estimated glomerular filtration rate < 90 mL/min/1.73 m2).

Conclusion

There is a low rate of recurrent VTE but significant end-organ morbidity in infants with unprovoked VTE.

Effect of Age on Hypertension Recognition in Children With Chronic Kidney Disease: A Report From the Chronic Kidney Disease in Children Study

BACKGROUND

Young age has been associated with poorer control of hypertension in children with chronic kidney disease (CKD). Using data from the CKiD Study (Chronic Kidney Disease in Children), we examined the relationship between age, hypertensive blood pressure (BP) recognition, and pharmacologic BP control in children with nondialysis-dependent CKD.

METHODS

Participants included 902 CKiD Study participants with CKD stages 2 to 4. A total of 3550 annual study visits met inclusion criteria and participants were stratified by age (0 to <7, ≥7 to <13, ≥13 to ≤18 years). Generalized estimating equations to account for repeated measures were applied to logistic regression analyses to evaluate the association of age with unrecognized hypertensive BP and medication use.

RESULTS

Children <7 years of age had a higher prevalence of hypertensive BP and a lower prevalence of antihypertensive medication use compared with older children. At visits where participants <7 years of age had hypertensive BP readings, 46% had unrecognized, untreated hypertensive BP compared with 21% of visits for children ≥13 years of age. The youngest age group was associated with higher odds of unrecognized hypertensive BP (adjusted odds ratio, 2.11 [95% CI, 1.37-3.24]) and lower odds of antihypertensive medication use among those with unrecognized hypertensive BP (adjusted OR, 0.51 [95% CI, 0.27-0.996]).

CONCLUSIONS

Children younger than 7 years of age with CKD are more likely to have both undiagnosed and undertreated hypertensive BP. Efforts to improve BP control in young children with CKD are needed to minimize development of cardiovascular disease and slow CKD progression.

Urinary DKK3 as a biomarker for short-term kidney function decline in children with chronic kidney disease: an observational cohort study

BACKGROUND

Childhood-onset chronic kidney disease is a progressive condition that can have a major effect on life expectancy and quality. We evaluated the usefulness of the kidney tubular cell stress marker urinary Dickkopf-related protein 3 (DKK3) in determining the short-term risk of chronic kidney disease progression in children and identifying those who will benefit from specific nephroprotective interventions.

METHODS

In this observational cohort study, we assessed the association between urinary DKK3 and the combined kidney endpoint (ie, the composite of 50% reduction of the estimated glomerular filtration rate [eGFR] or progression to end-stage kidney disease) or the risk of kidney replacement therapy (ie, dialysis or transplantation), and the interaction of the combined kidney endpoint with intensified blood pressure reduction in the randomised controlled ESCAPE trial. Moreover, urinary DKK3 and eGFR were quantified in children aged 3-18 years with chronic kidney disease and urine samples available enrolled in the prospective multicentre ESCAPE (NCT00221845; derivation cohort) and 4C (NCT01046448; validation cohort) studies at baseline and at 6-monthly follow-up visits. Analyses were adjusted for age, sex, hypertension, systolic blood pressure SD score (SDS), BMI SDS, albuminuria, and eGFR.

FINDINGS

659 children were included in the analysis (231 from ESCAPE and 428 from 4C), with 1173 half-year blocks in ESCAPE and 2762 in 4C. In both cohorts, urinary DKK3 above the median (ie, >1689 pg/mg creatinine) was associated with significantly greater 6-month eGFR decline than with urinary DKK3 at or below the median (-5·6% [95% CI -8·6 to -2·7] vs 1·0% [-1·9 to 3·9], p<0·0001, in ESCAPE; -6·2% [-7·3 to -5·0] vs -1·5% [-2·9 to -0·1], p<0·0001, in 4C), independently of diagnosis, eGFR, and albuminuria. In ESCAPE, the beneficial effect of intensified blood pressure control was limited to children with urinary DKK3 higher than 1689 pg/mg creatinine, in terms of the combined kidney endpoint (HR 0·27 [95% CI 0·14 to 0·55], p=0·0003, number needed to treat 4·0 [95% CI 3·7 to 4·4] vs 250·0 [66·9 to ∞]) and the need for kidney replacement therapy (HR 0·33 [0·13 to 0·85], p=0·021, number needed to treat 6·7 [6·1 to 7·2] vs 31·0 [27·4 to 35·9]). In 4C, inhibition of the renin-angiotensin-aldosterone system resulted in significantly lower urinary DKK3 concentrations (least-squares mean 12 235 pg/mg creatinine [95% CI 10 036 to 14 433] in patients not on angiotensin-converting enzyme inhibitors or angiotensin 2 receptor blockers vs 6861 pg/mg creatinine [5616 to 8106] in those taking angiotensin-converting enzyme inhibitors or angiotensin 2 receptor blockers, p<0·0001).

INTERPRETATION

Urinary DKK3 indicates short-term risk of declining kidney function in children with chronic kidney disease and might allow a personalised medicine approach by identifying those who benefit from pharmacological nephroprotection, such as intensified blood pressure lowering.

FUNDING

None.

Pregnancy History and Kidney Disease Progression Among Women Enrolled in Cure Glomerulonephropathy

Introduction

Preeclampsia increases the risk for future chronic kidney disease (CKD). Among those diagnosed with CKD, it is unclear whether a prior history of preeclampsia, or other complications in pregnancy, negatively impact kidney disease progression. In this longitudinal analysis, we assessed kidney disease progression among women with glomerular disease with and without a history of a complicated pregnancy.

Methods

Adult women enrolled in the Cure Glomerulonephropathy study (CureGN) were classified based on a history of a complicated pregnancy (defined by presence of worsening kidney function, proteinuria, or blood pressure; or a diagnosis of preeclampsia, eclampsia, or hemolysis, elevated liver enzymes, and low platelets [HELLP] syndrome), pregnancy without these complications, or no pregnancy history at CureGN enrollment. Linear mixed models were used to assess estimated glomerular filtration rate (eGFR) trajectories and urine protein-to-creatinine ratios (UPCRs) from enrollment.

Results

Over a median follow-up period of 36 months, the adjusted decline in eGFR was greater in women with a history of a complicated pregnancy compared to those with uncomplicated or no pregnancies (-1.96 [-2.67, -1.26] vs. -0.80 [-1.19, -0.42] and -0.64 [-1.17, -0.11] ml/min per 1.73 m2 per year, P = 0.007). Proteinuria did not differ significantly over time. Among those with a complicated pregnancy history, eGFR slope did not differ by timing of first complicated pregnancy relative to glomerular disease diagnosis.

Conclusions

A history of complicated pregnancy was associated with greater eGFR decline in the years following glomerulonephropathy (GN) diagnosis. A detailed obstetric history may inform counseling regarding disease progression in women with glomerular disease. Continued research is necessary to better understand pathophysiologic mechanisms by which complicated pregnancies contribute to glomerular disease progression.

Using Serum Cystatin C to Predict Acute Kidney Injury Following Infant Cardiac Surgery

Acute kidney injury (AKI) following cardiopulmonary bypass (CPB) is associated with increased morbidity and mortality. Serum Cystatin C (CysC) is a novel biomarker synthesized by all nucleated cells that may act as an early indicator of AKI following infant CPB. Prospective observational study of infants (< 1 year) requiring CPB during cardiac surgery. CysC was measured at baseline and 12, 24, 48, and 72 h following CPB initiation. Each post-op percent difference in CysC (e.g. %CysC12h) from baseline was calculated. Clinical variables along with urine output (UOP) and serum creatinine (SCr) were followed. Subjects were divided into two groups: AKI and non-AKI based upon the Kidney Disease Improving Global Outcomes (KDIGO) classification. AKI occurred in 41.9% (18) of the 43 infants enrolled. Patient demographics and baseline CysC levels were similar between groups. CysC levels were 0.97 ± 0.28 mg/L over the study period, and directly correlated with SCr (R = 0.71, p < 0.0001). Although absolute CysC levels were not significant between groups, the %CysC12h was significantly greater in the AKI group (AKI: - 16% ± 22% vs. Non-AKI - 28% ± 9% mg/L; p = 0.003). However, multivariate analysis demonstrated that a lower UOP (Odds Ratio:0.298; 95% CI 0.073, 0.850; p = 0.02) but not %CysC12h was independently associated with AKI. Despite a significant difference in the %CysC12h, only UOP was independently associated with AKI. Larger studies of a more homogenous population are needed to understand these results and to explore the variability in this biomarker seen across institutions.

Identification of Glomerular and Plasma Apolipoprotein M as Novel Biomarkers in Glomerular Disease

Introduction

Dysregulation of sphingolipid and cholesterol metabolism contributes to the pathogenesis of glomerular diseases (GDs). Apolipoprotein M (ApoM) promotes cholesterol efflux and modulates the bioactive sphingolipid sphingosine-1-phosphate (S1P). Glomerular ApoM expression is decreased in patients with focal segmental glomerulosclerosis (FSGS). We hypothesized that glomerular ApoM deficiency occurs in GD and that ApoM expression and plasma ApoM correlate with outcomes.

Methods

Patients with GD from the Nephrotic Syndrome Study Network (NEPTUNE) were studied. We compared glomerular mRNA expression of ApoM (gApoM), sphingosine kinase 1 (SPHK1), and S1P receptors 1 to 5 (S1PR1-5) in patients (n = 84) and controls (n = 6). We used correlation analyses to determine associations between gApoM, baseline plasma ApoM (pApoM), and urine ApoM (uApoM/Cr). We used linear regression to determine whether gApoM, pApoM, and uApoM/Cr were associated with baseline estimated glomerular filtration rate (eGFR) and proteinuria. Using Cox models, we determined whether gApoM, pApoM, and uApoM/Cr were associated with complete remission (CR) and the composite of end-stage kidney disease (ESKD) or ≥40% eGFR decline.

Results

gApoM was reduced (P < 0.01) and SPHK1 and S1PR1 to 5 expression was increased (P < 0.05) in patients versus controls, consistent with ApoM/S1P pathway modulation. gApoM positively correlated with pApoM in the overall cohort (r = 0.34, P < 0.01) and in the FSGS (r = 0.48, P < 0.05) and minimal change disease (MCD) (r = 0.75, P < 0.05) subgroups. Every unit decrease in gApoM and pApoM (log2) was associated with a 9.77 ml/min per 1.73 m2 (95% confidence interval [CI]: 3.96-15.57) and 13.26 ml/min per 1.73 m2 (95% CI: 3.57-22.96) lower baseline eGFR, respectively (P < 0.01). From Cox models adjusted for age, sex, or race, pApoM was a significant predictor of CR (hazard ratio [HR]: 1.85; 95% CI: 1.06-3.23).

Conclusions

pApoM is a potential noninvasive biomarker of gApoM deficiency and strongly associates with clinical outcomes in GD.

Associations of body mass index (BMI) and BMI change with progression of chronic kidney disease in children

BACKGROUND

Obesity is prevalent among children with chronic kidney disease (CKD) and is associated with cardiovascular disease and reduced quality of life. Its relationship with pediatric CKD progression has not been described.

METHODS

We evaluated relationships between both body mass index (BMI) category (normal, overweight, obese) and BMI z-score (BMIz) change on CKD progression among participants of the Chronic Kidney Disease in Children study. Kaplan-Meier survival curves and multivariable parametric failure time models depict the association of baseline BMI category on time to kidney replacement therapy (KRT). Additionally, the annualized percentage change in estimated glomerular filtration rate (eGFR) was modeled against concurrent change in BMIz using multivariable linear regression with generalized estimating equations which allowed for quantification of the effect of BMIz change on annualized eGFR change.

RESULTS

Participants had median age of 10.9 years [IQR: 6.5, 14.6], median eGFR of 50 ml/1.73 m2 [IQR: 37, 64] and 63% were male. 160 (27%) of 600 children with non-glomerular and 77 (31%) of 247 children with glomerular CKD progressed to KRT over a median of 5 years [IQR: 2, 8]. Times to KRT were not significantly associated with baseline BMI category. Children with non-glomerular CKD who were obese experienced significant improvement in eGFR (+ 0.62%; 95% CI: + 0.17%, + 1.08%) for every 0.1 standard deviation concurrent decrease in BMI. In participants with glomerular CKD who were obese, BMIz change was not significantly associated with annualized eGFR change.

CONCLUSION

Obesity may represent a target of intervention to improve kidney function in children with non-glomerular CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Long-Term Kidney and Cardiovascular Complications in Pediatric Cancer Survivors

OBJECTIVE

The objective of this study was to describe the burden of adverse kidney and hypertension outcomes in patients evaluated by pediatric nephrology in a multidisciplinary survivorship clinic.

STUDY DESIGN

Retrospective chart review of all patients followed up by nephrology in our multidisciplinary survivorship clinic from August 2013 to June 2021. Data included clinic blood pressure, longitudinal ambulatory blood pressure monitoring (ABPM), echocardiography, serum creatinine, and first-morning urine protein/creatinine ratios. For patients with multiple ABPMs, results of initial and most recent ABPMs were compared.

RESULTS

Of 422 patients followed in the multidisciplinary cancer survivorship clinic, 130 were seen by nephrology. The median time after therapy completion to first nephrology visit was 8 years. The most common diagnoses were leukemia/myelodysplastic syndrome (27%), neuroblastoma (24%), and Wilms tumor (15%). At the last follow-up, 68% had impaired kidney function, 38% had a clinical diagnosis of hypertension, and 12% had proteinuria. There were 91 ABPMs performed in 55 (42%) patients. Patients with multiple ABPMs (n = 21) had statistically significant reductions in overall median blood pressure loads: systolic initial load 37% vs most recent 10% (P = .005) and diastolic load 36% vs 14% (P = .017). Patients with impaired kidney function were more likely to have received ifosfamide. Patients with hypertension were more likely to have received total body irradiation or allogeneic stem cell transplant.

CONCLUSIONS

History of leukemia/myelodysplastic syndrome, neuroblastoma, and Wilms tumor was frequent among survivors seen by nephrology. There was significant improvement in cardiovascular measures with increased recognition of hypertension and subsequent treatment.

A longitudinal analysis of the effect of anemia on executive functions in children with mild to moderate chronic kidney disease

BACKGROUND

Children with chronic kidney disease (CKD) are at risk for cognitive dysfunction. The aim of this study was to investigate associations between executive functions (EF), anemia, and iron deficiency.

METHODS

A total of 688 children > 6 years of age enrolled in the Chronic Kidney Disease in Children (CKiD) study who underwent evaluation for EF were included. Hemoglobin (Hgb) was characterized as low (1st-5th percentile) or very low (< 1st percentile) compared to normative values for age, sex, and race irrespective of erythropoiesis-stimulating agent (ESA) usage. Longitudinal analysis was conducted using consecutive visit pairs, with anemia status defined as new onset, resolved, or persistent. Linear mixed models with random intercept were used and adjusted for key covariates.

RESULTS

Anemia was present in 41% of children, and median Hgb was 11.8 gm/dl. New onset anemia was associated with lower digit span total score (- 0.75, 95% CI - 1.36, - 0.15, p = 0.01). Persistent anemia was associated with lower scores on color-word inhibition/switching (β =  - 0.98; 95% CI - 1.78, - 0.18, p = 0.02). Errors of omission were significantly higher (worse) in those with persistent anemia (β = 2.67, 95% CI 0.18, 5.17, p = 0.04). Very low Hgb levels were significantly associated with lower color-word inhibition/switching scores (β =  - 1.33, 95% CI - 2.16, - 0.51; p = 0.002). Anemia and low GFR were associated with lower category fluency scores compared to non-anemic subjects with higher GFR (β =  - 1.09, 95% CI - 2.09, - 0.10, p = 0.03).

CONCLUSIONS

The presence of anemia, in addition to its severity and duration in children with CKD, is associated with poorer scores on select measures of EF. A higher resolution version of the Graphical abstract is available as Supplementary information.

Vitamin D supplementation in children and young adults with persistent proteinuria secondary to glomerular disease

BACKGROUND

Vitamin D deficiency is common in glomerular disease. Supplementation may be ineffective due to ongoing urinary losses of vitamin D binding protein. We sought to determine if daily cholecalciferol supplementation would increase vitamin D concentrations in children with glomerular disease and persistent proteinuria, without adverse effects.

METHODS

Eighteen participants at least 5 years of age with primary glomerular disease and urine protein:creatinine ratio ≥ 0.5 were enrolled from four pediatric nephrology practices to receive cholecalciferol supplementation: 4,000 IU or 2,000 IU per day for serum 25 hydroxyvitamin vitamin D (25OHD) concentrations < 20 ng/mL and 20 ng/mL to < 30 ng/mL, respectively. Measures of vitamin D and mineral metabolism were obtained at baseline and weeks 6 and 12. Multivariable generalized estimating equation (GEE) regression estimated mean percent changes in serum 25OHD concentration.

RESULTS

Median baseline 25OHD was 12.8 ng/mL (IQR 9.3, 18.9) and increased to 27.8 ng/mL (20.5, 36.0) at week 6 (p < 0.001) without further significant increase at week 12. A total of 31% of participants had a level ≥ 30 ng/mL at week 12. Supplementation was stopped in two participants at week 6 for mildly elevated calcium and phosphorus, respectively, with subsequent declines in 25OHD of > 20 ng/mL. In the adjusted GEE model, 25OHD was 102% (95% CI: 64, 141) and 96% (95% CI: 51, 140) higher versus baseline at weeks 6 and 12, respectively (p < 0.001).

CONCLUSION

Cholecalciferol supplementation in vitamin D deficient children with glomerular disease and persistent proteinuria safely increases 25OHD concentration. Ideal dosing to fully replete 25OHD concentrations in this population remains unknown.

CLINICAL TRIAL

NCT01835639. A higher resolution version of the Graphical abstract is available as Supplementary information.

Renal fluid and acid/base balance during refeeding in restrictive eating disorders

BACKGROUND AND OBJECTIVES

Fluid shifts have been ascribed to central diabetes insipidus in patients with anorexia nervosa hospitalized for refeeding. Recent data, however, suggest that vasopressin production is not dysregulated in this population. Our objective was to describe the trajectory of fluid imbalances in relationship to kidney function, electrolyte disturbances, and acid/base balance during refeeding.

METHODS

A retrospective review of daily fluid balance and biochemical values was performed in 70 sequential unique patients admitted to University of California at Los Angeles Hospital Medical Stabilization Program for Eating Disorders from December 2018 to November 2020.

RESULTS

Participants (2 males/68 females) were between 10 and 24 years of age and with a median body mass index of 16.1 (14.3, 18.1) kg/m² . A severe negative fluid balance (>-900 ml/day) was observed in 80% of patients at some point during hospitalization. Serum sodium concentrations were normal on admission and remained stable during refeeding. Serum bicarbonate concentrations were 25 ± 1 mEq/dl on admission and increased above the normal range in 31% of patients. Metabolic alkalosis was inversely associated with the development of a negative fluid balance. Estimated glomerular filtration rate was impaired in 54% of patients, improved with refeeding, and was not associated with the development of a severe negative fluid balance or metabolic alkalosis.

DISCUSSION

Chronic energy deprivation alters the physiology of renal fluid and bicarbonate handling in ways that are independent of vasopressin and glomerular filtration. Further studies are warranted to understand the renal adaptations that occur during energy restriction and subsequent refeeding.

PUBLIC SIGNIFICANCE

Massive urinary fluid losses occur in patients with restrictive eating disorders hospitalized for refeeding. In addition, many patients have impaired renal bicarbonate excretion. These findings suggest that chronic energy deprivation impairs the kidney's ability to handle the shifts in fluid and acid/base balance that occur when appropriate oral nutrition is re-introduced.

Rapid Progression of Focal Segmental Glomerulosclerosis in Patients with High-Risk APOL1 Genotypes

BACKGROUND

FSGS is a heterogeneous diagnosis with a guarded prognosis. Polymorphisms in the apolipoprotein L1 ( APOL1 ) gene are associated with developing FSGS and faster progression to kidney failure in affected patients. Better understanding the natural history of patients with FSGS and APOL1 risk alleles is essential to improve patient care and support the design and interpretation of interventional studies. The objective of this study was to evaluate the quantitative association between APOL1 and kidney disease progression and the interaction with other clinical and laboratory factors.

METHODS

CureGN cohort study participants with biopsy diagnosis of FSGS, regardless of self-identified race, were included. The exposure of interest was two APOL1 risk alleles (high risk) versus zero to one risk alleles (low risk). The primary outcome was eGFR slope categorized as rapid progressor (eGFR slope ≤-5 ml/min per year), intermediate progressor (slope between 0 and -5), or nonprogressor (slope ≥0). Multivariable ordinal logistic and linear regressions were used for adjusted analyses. Missing data were addressed using multiple imputation.

RESULTS

Of 650 participants, 476 (73%) had genetic testing, among whom 87 (18%) were high risk. High-risk participants were more likely to have lower median eGFR (62 [interquartile range, 36-81] versus low-risk participants 76 ml/min per 1.73 m 2 [interquartile range, 44-106]; P <0.01). In adjusted analysis, the odds of more rapid progression of eGFR was 2.75 times higher (95% confidence interval, 1.67 to 4.53; P <0.001) in the high-risk versus low-risk groups.

CONCLUSIONS

In patients with FSGS, high-risk APOL1 genotype is the predominant factor associated with more rapid loss of kidney function.

Deep learning imaging features derived from kidney ultrasounds predict chronic kidney disease progression in children with posterior urethral valves

BACKGROUND

We sought to use deep learning to extract anatomic features from postnatal kidney ultrasounds and evaluate their performance in predicting the risk and timing of chronic kidney disease (CKD) progression for boys with posterior urethral valves (PUV). We hypothesized that these features would predict CKD progression better than clinical characteristics such as nadir creatinine alone.

METHODS

We performed a retrospective cohort study of boys with PUV treated at two pediatric health systems from 1990 to 2021. Features of kidneys were extracted from initial postnatal kidney ultrasound images using a deep learning model. Three time-to-event prediction models were built using random survival forests. The Imaging Model included deep learning imaging features, the Clinical Model included clinical data, and the Ensemble Model combined imaging features and clinical data. Separate models were built to include time-dependent clinical data that were available at 6 months, 1 year, 3 years, and 5 years.

RESULTS

Two-hundred and twenty-five patients were included in the analysis. All models performed well with C-indices of 0.7 or greater. The Clinical Model outperformed the Imaging Model at all time points with nadir creatinine driving the performance of the Clinical Model. Combining the 6-month Imaging Model (C-index 0.7; 95% confidence interval [CI] 0.6, 0.79) with the 6-month Clinical Model (C-index 0.79; 95% CI 0.71, 0.86) resulted in a 6-month Ensemble Model that performed better (C-index 0.82; 95% CI 0.77, 0.88) than either model alone.

CONCLUSIONS

Deep learning imaging features extracted from initial postnatal kidney ultrasounds may improve early prediction of CKD progression among children with PUV. A higher resolution version of the Graphical abstract is available as Supplementary information.

Mineral bone disorders and kidney disease in hospitalized children with sickle cell anemia

Background

Mineral bone disorders (MBD) are common in sickle cell anemia (SCA). Frequent vaso-occlusive crises (VOC) further impact MBD in children with SCA. We evaluated the prevalence of markers of SCA-related MBD (sMBD) in hospitalized children and assessed the relationship between sMBD and individual mineral abnormalities with kidney disease.

Methods

We prospectively recruited 185 children with SCA hospitalized with a VOC. Serum measures of mineral bone metabolism (calcium, phosphate, parathyroid hormone, 25-hydroxy vitamin D, FGF23, osteopontin) were measured at enrollment. The primary outcome was markers of sMBD defined as a composite of hypocalcemia, hyperphosphatemia, hyperparathyroidism, or deficiency in 25-OH vitamin D. Secondary outcomes included individual abnormalities in mineral metabolism. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines were used to define SCA-associated acute kidney injury (AKI). AKI was further assessed using urine NGAL as a marker of tubular injury. Acute kidney disease (AKD) was defined as a composite of AKI, an eGFR < 90 ml/min per 1.73 m2 using the Cystatin C GFR equation, or evidence of structural injury (positive biomarker test or albuminuria).

Results

The mean age of children was 8.9 years and 41.6% were female. The prevalence of sMBD was 47.6%, with hypocalcemia the most frequent abnormality (29.9%, 55/184) followed by hyperphosphatemia (20.7%, 38/184), hyperparathyroidism (8.7%, 16/185), and vitamin D deficiency (5.4%, 10/185). There was no association between sMBD and sKDIGO-defined AKI using serial changes in creatinine or when incorporating biomarkers to define AKI. However, the presence of AKD was associated with a 2.01-fold increased odds of sMBD (95% CI 1.05 to 3.83) and was driven by a decrease in eGFR (OR, 2.90 95% CI: 1.59 to 5.29). When evaluating individual mineral abnormalities, hypocalcemia was associated with AKD and low eGFR while hyperparathyroidism was associated with low eGFR, AKI and structural injury. Vitamin D deficiency was associated with structural kidney injury. Vitamin D deficiency, hyperparathryoidism, and increases in FGF23 and osteopontin predicted mortality (p < 0.05 for all).

Conclusion

MBD is common among children with SCA hospitalized with VOC. Biomarkers of kidney injury and bone health may help risk stratify children at risk of sMBD. Routine evaluation of sMBD in children with SCA may improve long-term bone health.

Longitudinal changes in uric acid concentration and their relationship with chronic kidney disease progression in children and adolescents

BACKGROUND

Elevated serum uric acid concentration is a risk factor for CKD progression. Its change over time and association with CKD etiology and concomitant changes in estimated glomerular filtration rate (eGFR) in children and adolescents are unknown.

METHODS

Longitudinal study of 153 children/adolescents with glomerular (G) and 540 with non-glomerular (NG) etiology from the CKD in Children (CKiD) study. Baseline serum uric acid, change in uric acid and eGFR over time, CKD etiology, and comorbidities were monitored. Adjusted linear mixed-effects regression models quantified the relationship between within-person changes in uric acid and concurrent within-person changes in eGFR.

RESULTS

Participants with stable uric acid over follow-up had CKD progression which became worse for increased baseline uric acid (average annual percentage changes in eGFR were - 1.4%, - 7.7%, and - 14.7% in those with G CKD with baseline uric acid < 5.5 mg/dL, 5.5 - 7.5 mg/dL, and > 7.5 mg/dL, respectively; these changes were - 1.4%, - 4.1%, and - 8.6% in NG CKD). Each 1 mg/dL increase in uric acid over follow-up was independently associated with significant concomitant eGFR decreases of - 5.7% (95%CI - 8.4 to - 3.0%) (G) and - 5.1% (95%CI - 6.3 to - 4.0%) (NG) for those with baseline uric acid < 5.5 mg/dL and - 4.3% (95%CI - 6.8 to - 1.6%) (G) and - 3.3% (95%CI - 4.1 to - 2.6%) (NG) with baseline uric acid between 5.5 and 7.5 mg/dL.

CONCLUSIONS

Higher uric acid levels and increases in uric acid over time are risk factors for more severe progression of CKD in children and adolescents. A higher resolution version of the Graphical abstract is available as Supplementary information.

Evaluating Kidney Function Decline in Children with Chronic Kidney Disease Using a Multi-Institutional Electronic Health Record Database

BACKGROUND

The objectives of this study were to use electronic health record data from a US national multicenter pediatric network to identify a large cohort of children with CKD, evaluate CKD progression, and examine clinical risk factors for kidney function decline.

METHODS

This retrospective cohort study identified children seen between January 1, 2009, to February 28, 2022. Data were from six pediatric health systems in PEDSnet. We identified children aged 18 months to 18 years who met criteria for CKD: two eGFR values <90 and ≥15 ml/min per 1.73 m2 separated by ≥90 days without an intervening value ≥90. CKD progression was defined as a composite outcome: eGFR <15 ml/min per 1.73 m2, ≥50% eGFR decline, long-term dialysis, or kidney transplant. Subcohorts were defined based on CKD etiology: glomerular, nonglomerular, or malignancy. We assessed the association of hypertension (≥2 visits with hypertension diagnosis code) and proteinuria (≥1 urinalysis with ≥1+ protein) within 2 years of cohort entrance on the composite outcome.

RESULTS

Among 7,148,875 children, we identified 11,240 (15.7 per 10,000) with CKD (median age 11 years, 50% female). The median follow-up was 5.1 (interquartile range 2.8-8.3) years, the median initial eGFR was 75.3 (interquartile range 61-83) ml/min per 1.73 m2, 37% had proteinuria, and 35% had hypertension. The following were associated with CKD progression: lower eGFR category (adjusted hazard ratio [aHR] 1.44 [95% confidence interval (95% CI), 1.23 to 1.69], aHR 2.38 [95% CI, 2.02 to 2.79], aHR 5.75 [95% CI, 5.05 to 6.55] for eGFR 45-59 ml/min per 1.73 m2, 30-44 ml/min per 1.73 m2, 15-29 ml/min per 1.73 m2 at cohort entrance, respectively, when compared with eGFR 60-89 ml/min per 1.73 m2), glomerular disease (aHR 2.01 [95% CI, 1.78 to 2.28]), malignancy (aHR 1.79 [95% CI, 1.52 to 2.11]), proteinuria (aHR 2.23 [95% CI, 1.89 to 2.62]), hypertension (aHR 1.49 [95% CI, 1.22 to 1.82]), proteinuria and hypertension together (aHR 3.98 [95% CI, 3.40 to 4.68]), count of complex chronic comorbidities (aHR 1.07 [95% CI, 1.05 to 1.10] per additional comorbid body system), male sex (aHR 1.16 [95% CI, 1.05 to 1.28]), and younger age at cohort entrance (aHR 0.95 [95% CI, 0.94 to 0.96] per year older).

CONCLUSIONS

In large-scale real-world data for children with CKD, disease etiology, albuminuria, hypertension, age, male sex, lower eGFR, and greater medical complexity at start of follow-up were associated with more rapid decline in kidney function.

The Investigation of Kidney Involvement in 430 Hospitalized Patients with Omicron COVID-19 in Tianjin, China

INTRODUCTION

This study evaluated the incidence, clinical characteristics, and risk factors of kidney involvement in patients with the Omicron variant infection in the post-acute treatment phase in Tianjin, China.

METHODS

Data were collected from 430 patients with Omicron variant infection in Tianjin, China. Demographics, comorbidities, laboratory blood tests, urinalysis, vaccination status, and COVID-19 clinical classification were assessed. Patients were grouped based on kidney involvement, and associated risk factors of kidney involvement were also investigated.

RESULTS

Asymptomatic, mild, ordinary, and severe patients with Omicron COVID-19 variant comprised 1.5%, 49.1%, 48.9%, and 0.5% of the sample population, respectively, without critical illness or death. The incidences of hematuria, proteinuria, and concurrent hematuria and proteinuria were 14.7%, 14.2%, and 5.1%, respectively. Patients with and without kidney involvement differed in age, body mass index (BMI), comorbidity, creatinine levels, estimated glomerular filtration rate, and C-reactive protein (CRP) levels. Age, hypertension, higher CRP levels, and higher BMI were linked with kidney involvement.

CONCLUSION

The majority of the patients suffered from mild or ordinary symptoms of Omicron COVID-19 infection. The primary kidney involvement was hematuria and proteinuria. Proteinuria was significantly associated with Omicron variant infection, and patients with hypertensive comorbidity, higher CRP, and higher creatinine levels were at increased risk of proteinuria after Omicron variant infection.

Uncovering risk factors for kidney injury in children with a solitary functioning kidney

Children with a solitary functioning kidney (SFK) have an increased risk of kidney injury. The exact risk of and risk factors for kidney injury remain unknown, which impedes personalized care. Here, we recruited a nationwide multicenter cohort of 944 patients with SFK to get more insight into this by consenting patients born in 1993-2020 and diagnosed with congenital or acquired SFK before adulthood. The median follow-up was 12.8 years and four indications of kidney injury were studied: urine protein-creatinine ratios, blood pressure, estimated glomerular filtration rate and use of anti-hypertensive/proteinuric medication. For each indicator except medication use, separate cut-off values for any injury and severe injury were used. Survival analyses indicated that at 18 years of age, any or severe kidney injury were present in 75% and 39% of patients with congenital SFK, respectively. Risk factors for kidney injury included kidney agenesis as cause of the SFK, anomalies in the SFK, and high body mass index at last follow-up. Kidney agenesis and being overweight were specifically associated with proteinuria and high blood pressure, whereas anomalies in the SFK were associated with reduced estimated glomerular filtration rates. The high prevalence of kidney injury in patients with SFK emphasizes the need for long-term follow-up, in which lifestyle is an important topic to address. More research into the etiological role of risk factors will help to translate our findings into individualized care strategies. Thus, our study shows that a significant proportion of children with SFK will develop kidney injury over time.

Sporadic Case of Heterozygous X-Linked Alport Syndrome

Alport syndrome is a genetically and phenotypically heterogeneous disorder that can be transmitted in an X-linked, autosomal recessive, or autosomal dominant fashion and can affect glomerular, cochlear, and ocular basement membranes. The disorder results from mutations in the collagen IV genes COL4A5 (X chromosome), COL4A3, and COL4A4. Alport patients are at lifetime risk for kidney failure, sensorineural deafness, and ocular abnormalities. Males with Alport syndrome typically present with severe phenotype with progression to end-stage kidney disease and/or sensorineural deafness and eye changes. Females generally having less severe presentation and diagnosis of X-linked Alport syndrome are generally not considered. Here, we report a case of a 3-year-old girl with gross hematuria, proteinuria, and chronic kidney disease who was found to have features of Alport syndrome on kidney biopsy and a sporadic heterozygous pathogenic COL4A5 deletion on molecular testing. This case report emphasizes the importance of kidney biopsy and molecular testing in the work up of pediatric patients with hematuria, proteinuria, and/or chronic kidney disease. It is also a poignant illustration that females with heterozygous X-linked COL4A5 mutations are often affected patients. It further illustrates the phenomenon of sporadic occurrence of genetic kidney disease in the absence of family history of kidney disease.

Cure Glomerulonephropathy Pathology Classification and Core Scoring Criteria, Reproducibility, and Clinicopathologic Correlations

Introduction

Cure Glomerulonephropathy (CureGN) is an observational cohort study of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), or IgA nephropathy. We developed a conventional, consensus-based scoring system to document pathologic features for application across multiple pathologists and herein describe the protocol, reproducibility, and correlation with clinical parameters at biopsy.

Methods

Definitions were established for glomerular, tubular, interstitial, and vascular lesions evaluated semiquantitatively using digitized light microscopy slides and electron micrographs, and reported immunofluorescence. Cases with curated pathology materials as of April 2019 were scored by a randomly assigned pathologist, with at least 10% of cases scored by a second pathologist. Scoring reproducibility was assessed using Gwet's agreement coefficient (AC)1 statistic and correlations with clinical variables were performed.

Results

Of 800 scored biopsies (134 MCD, 194 FSGS, 206 MN, 266 IgA), 94 were scored twice (11.8%). Of 60 pathology features, 46 (76.7%) demonstrated excellent (AC1>0.8), and 12 (20.0%) had good (AC1 0.6-0.8) reproducibility. Mesangial hypercellularity scored as absent, focal, or diffuse had moderate reproducibility (AC1 = 0.58), but good reproducibility (AC1 = 0.71) when scored as absent or focal versus diffuse. The percent glomeruli scored as no lesions had fair reproducibility (AC1 = 0.34). Strongest correlations between pathologic features and clinical characteristics at biopsy included interstitial inflammation, interstitial fibrosis, and tubular atrophy with estimated glomerular filtration rate, foot process effacement with urine protein/creatinine ratio, and active crescents with hematuria.

Conclusions

Most scored pathology features showed excellent reproducibility, demonstrating consistency for these features across multiple pathologists. Correlations between certain pathologic features and expected clinical characteristics show the value of this approach for future studies on clinicopathologic correlations and biomarker discovery.

Glomerular filtration rate in critically ill neonates and children: creatinine-based estimations versus iohexol-based measurements

BACKGROUND

Acute kidney injury (AKI) and augmented renal clearance (ARC), both alterations of the glomerular filtration rate (GFR), are prevalent in critically ill children and neonates. AKI and ARC prevalence estimates are based on estimation of GFR (eGFR) using serum creatinine (SCr), which is known to be inaccurate. We aimed to test our hypothesis that AKI prevalence will be higher and ARC prevalence will be lower in critically ill children when using iohexol-based measured GFR (mGFR), rather than using eGFR. Additionally, we aimed to investigate the performance of different SCr-based eGFR methods.

METHODS

In this single-center prospective study, critically ill term-born neonates and children were included. mGFR was calculated using a plasma disappearance curve after parenteral administration of iohexol. AKI diagnosis was based on the KDIGO criteria, SCr-based eGFR, and creatinine clearance (CrCL). Differences between eGFR and mGFR were determined using Wilcoxon signed-rank tests and by calculating bias and accuracy (percentage of eGFR values within 30% of mGFR values).

RESULTS

One hundred five children, including 43 neonates, were included. AKI prevalence was higher based on mGFR (48%), than with KDIGO or eGFR (11-40%). ARC prevalence was lower with mGFR (24%) compared to eGFR (38-51%). eGFR equations significantly overestimated mGFR (60-71 versus 41 ml/min/1.73 m², p < 0.001-0.002). Accuracy was highest with eGFR equations based on age- and sex-dependent equations (up to 59%).

CONCLUSION

Iohexol-based AKI prevalence was higher and ARC prevalence lower compared to standard SCr-based eGFR methods. Age- and sex-dependent equations for eGFR (eGFR-Smeets for neonates and eGFR-Pierce for children) best approached measured GFR and should preferably be used to optimize diagnosis of AKI and ARC in this population. A higher resolution version of the Graphical abstract is available as Supplementary information.

Presentation of SLE after COVID vaccination in a pediatric patient

BACKGROUND

The outbreak of severe acute respiratory syndrome coronavirus 2 has had an enormous impact on global health. Vaccination remains one of the most effective interventions for disease prevention. Clinically significant vaccine side effects are uncommon, though autoimmune-mediated disease occurs in a small percentage of vaccine recipients. Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that is associated with significant morbidity and mortality. Childhood-onset SLE tends to have more severe disease manifestations than adult-onset SLE. In adults, there are a few reported cases of SLE developing soon after coronavirus disease 2019 (COVID-19) mRNA vaccination.

CASE PRESENTATION

A 14-year-old previously healthy male developed laboratory and clinical evidence of SLE, including maculopapular malar rash, arthritis, pleuritic chest pain, and class V (membranous) lupus nephritis, 2 days after his third dose of the Pfizer-BioNTech COVID-19 vaccine. The patient's symptoms improved after initiation of prednisone and mycophenolate mofetil. We also summarize eleven prior case reports describing SLE after COVID-19 vaccine in adults.

CONCLUSION

To our knowledge, this is the first reported pediatric patient with new onset SLE following COVID-19 mRNA vaccination. While potential mechanistic links exist between COVID-19 vaccination and SLE development, additional studies are necessary to elucidate the exact nature of this relationship.

Assessment of Kidney Function in Children

A good understanding of kidney function tests is essential for patient care. Urinalysis is the commonest used test for screening purposes in ambulatory settings. Glomerular function is assessed further by urine protein excretion and estimated glomerular filtration rate and tubular function by various tests such as urine anion gap and excretion of sodium, calcium, and phosphate. In addition, kidney biopsy and/or genetic analyses may be required to further characterize the underlying kidney disease. In this article, we discuss maturation and the assessment of kidney function in children.