Delayed menarche in girls with chronic kidney disease and the association with short stature

BACKGROUND

Children with chronic kidney disease (CKD) have delays in normal growth and pubertal development. We describe factors associated with delayed menarche and the association of delayed menarche with short stature in girls with CKD.

METHODS

Two hundred eighty-seven girls with CKD onset prior to menarche within the Chronic Kidney Disease in Children (CKiD) cohort were studied. Delayed menarche was defined as menarche at age 15 years or older; short stature was defined as last available height 2 standard deviations below projected adult height. Kaplan-Meier cumulative incidence function was used to estimate median age at menarche. Chi-squared and Wilcoxon rank-sum tests were used to assess factors associated with delayed menarche. Chi-squared test was used to evaluate the association between delayed menarche and short stature.

RESULTS

Among 287 girls, 68 enrolled with prevalent menarche, 131 were observed to have incident menarche, and 88 were pre-menarchal at their last study visit. Median age at menarche was 12 years. Ten percent had delayed menarche. African American race, lower estimated glomerular filtration rate, ever corticosteroid use, and longer CKD duration were associated with delayed menarche (p < 0.05). Girls with delayed menarche had lower height and weight percentiles at the time of menarche (p < 0.05). Sixty-one percent of girls with delayed menarche had short stature compared with only 35% of girls without delayed menarche (p = 0.03).

CONCLUSION

Median age at menarche is similar among girls with CKD and healthy girls. Ten percent of girls with CKD had delayed menarche and may be at risk for short stature.

Adiposity, Sex, and Cardiovascular Disease Risk in Children With CKD: A Longitudinal Study of Youth Enrolled in the Chronic Kidney Disease in Children (CKiD) Study

RATIONALE & OBJECTIVE

Traditional and nontraditional cardiovascular disease risk factors are highly prevalent in children with chronic kidney disease (CKD). We examined the longitudinal association of adiposity with cardiac damage among children with CKD and explored whether this association was modified by sex.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Children with mild-to-moderate CKD enrolled in the Chronic Kidney Disease in Children (CKiD) Study at 49 pediatric nephrology centers across North America.

EXPOSURE

Age- and sex-specific body mass index (BMI) z score.

OUTCOME

Age- and sex-specific left ventricular mass index (LVMI) z score and left ventricular hypertrophy (LVH).

ANALYTICAL APPROACH

Longitudinal analyses using mixed-effects models to estimate sex-specific associations of BMI z scores with LVMI z score and with LVH, accounting for repeated measurements over time.

RESULTS

Among 725 children with 2,829 person-years of follow-up, median age was 11.0 years and median estimated glomerular filtration rate was 52.6mL/min/1.73m2. Nearly one-third of both boys and girls were overweight or obese, median LVMI z score was 0.18 (IQR: -0.67, 1.08), and 11% had LVH. Greater BMI z scores were independently associated with greater LVMI z scores and greater odds of LVH. For each 1-unit higher BMI z score, LVMI z score was 0.24 (95% CI, 0.17-0.31) higher in boys and 0.38 (95% CI, 0.29-0.47) higher in girls (Pinteraction = 0.01). For each 1-unit higher BMI z score, the odds of LVH was 1.5-fold (95% CI, 1.1-2.1) higher in boys and 3.1-fold (95% CI, 1.8-4.4) higher in girls (Pinteraction = 0.005).

LIMITATIONS

Not all children had repeated measurements. LVH is a surrogate and not a hard cardiac outcome. The observational design limits causal inference.

CONCLUSIONS

In children, adiposity is independently associated with the markers of cardiac damage, LVMI z score and LVH. This association is stronger among girls than boys. Pediatric overweight and obesity may therefore have a substantial impact on cardiovascular risk among children with CKD.

Multi-instance Deep Learning of Ultrasound Imaging Data for Pattern Classification of Congenital Abnormalities of the Kidney and Urinary Tract in Children

OBJECTIVE

To reliably and quickly diagnose children with posterior urethral valves (PUV), we developed a multi-instance deep learning method to automate image analysis.

METHODS

We built a robust pattern classifier to distinguish 86 children with PUV from 71 children with mild unilateral hydronephrosis based on ultrasound images (3504 in sagittal view and 2558 in transverse view) obtained during routine clinical care.

RESULTS

The multi-instance deep learning classifier performed better than classifiers built on either single sagittal images or single transverse images. Particularly, the deep learning classifiers built on single images in the sagittal view and single images in the transverse view obtained area under the receiver operating characteristic curve (AUC) values of 0.796 ± 0.064 and 0.815 ± 0.071, respectively. AUC values of the multi-instance deep learning classifiers built on images in the sagittal and transverse views with mean pooling operation were 0.949 ± 0.035 and 0.954 ± 0.033, respectively. The multi-instance deep learning classifiers built on images in both the sagittal and transverse views with a mean pooling operation obtained an AUC of 0.961 ± 0.026 with a classification rate of 0.925 ± 0.060, specificity of 0.986 ± 0.032, and sensitivity of 0.873 ± 0.120, respectively. Discriminative regions of the kidney located using classification activation mapping demonstrated that the deep learning techniques could identify meaningful anatomical features from ultrasound images.

CONCLUSION

The multi-instance deep learning method provides an automatic and accurate means to extract informative features from ultrasound images and discriminate infants with PUV from male children with unilateral hydronephrosis.

Establishing core outcome domains in pediatric kidney disease: report of the Standardized Outcomes in Nephrology-Children and Adolescents (SONG-KIDS) consensus workshops

Trials in children with chronic kidney disease do not consistently report outcomes that are critically important to patients and caregivers. This can diminish the relevance and reliability of evidence for decision making, limiting the implementation of results into practice and policy. As part of the Standardized Outcomes in Nephrology-Children and Adolescents (SONG-Kids) initiative, we convened 2 consensus workshops in San Diego, California (7 patients, 24 caregivers, 43 health professionals) and Melbourne, Australia (7 patients, 23 caregivers, 49 health professionals). This report summarizes the discussions on the identification and implementation of the SONG-Kids core outcomes set. Four themes were identified; survival and life participation are common high priority goals, capturing the whole child and family, ensuring broad relevance across the patient journey, and requiring feasible and valid measures. Stakeholders supported the inclusion of mortality, infection, life participation, and kidney function as the core outcomes domains for children with chronic kidney disease.

Bicarbonate, blood pressure, and executive function in pediatric CKD-is there a link?

BACKGROUND

In adult chronic kidney disease (CKD), metabolic acidosis is associated with diminished cognition, notably executive function (EF). Data from the Chronic Kidney Disease in Children (CKiD) study demonstrate a risk for impairment of EF, a finding associated with heightened blood pressure variability (BPV). We sought to determine whether low serum bicarbonate is also associated with performance on tests of EF in pediatric CKD and to investigate potential interaction with BPV.

METHODS

CKiD participants with serum bicarbonate, blood pressure, and selected cognitive measurements available were evaluated. An EF summary score was derived from scores on the Delis-Kaplan Executive Function System, Conners' Continuous Performance Test, and Digit Span Backwards subtest from the Wechsler Intelligence Scale for Children-IV-Integrated. Parents completed the Behavioral Rating Inventory of Executive Function (BRIEF) to yield a Global Executive Composite (GEC) score. Linear mixed models with bicarbonate and hypertension as predictors and linear regression with bicarbonate and BPV were used to predict EF level.

RESULTS

Data were available for 865 children. Twenty-two percent had low bicarbonate (CO₂ ≤ 20 mmol/L) at baseline. On multivariate analysis, there was no relationship between bicarbonate, hypertension, and EF. There was no significant CO₂×hypertension interaction found. A significant interaction (p = 0.01) between high CO₂ (≥ 26 mmol/L) and BPV was detected in the model with GEC as the EF outcome, indicating that while higher BPV was associated with worse EF in the low and normal CO₂ groups, higher BPV was associated with better EF in the high CO₂ group.

CONCLUSIONS

Our analyses revealed an interaction between one measure of BPV and low bicarbonate on neurocognition in pediatric CKD, suggesting a potential role for control of both bicarbonate and blood pressure in preserving cognition in early CKD. Further research is needed to confirm and further define this association.

Low Serum Bicarbonate and CKD Progression in Children

BACKGROUND AND OBJECTIVES

Studies of adults have demonstrated an association between metabolic acidosis, as measured by low serum bicarbonate levels, and CKD progression. We evaluated this relationship in children using data from the Chronic Kidney Disease in Children study.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The relationship between serum bicarbonate and a composite end point, defined as 50% decline in eGFR or KRT, was described using parametric and semiparametric survival methods. Analyses were stratified by underlying nonglomerular and glomerular diagnoses, and adjusted for demographic characteristics, eGFR, proteinuria, anemia, phosphate, hypertension, and alkali therapy.

RESULTS

Six hundred and three participants with nonglomerular disease contributed 2673 person-years of follow-up, and 255 with a glomerular diagnosis contributed 808 person-years of follow-up. At baseline, 39% (237 of 603) of participants with nonglomerular disease had a bicarbonate level of ≤22 meq/L and 36% (85 of 237) of those participants reported alkali therapy treatment. In participants with glomerular disease, 31% (79 of 255) had a bicarbonate of ≤22 meq/L, 18% (14 of 79) of those participants reported alkali therapy treatment. In adjusted longitudinal analyses, compared with participants with a bicarbonate level >22 meq/L, hazard ratios associated with a bicarbonate level of <18 meq/L and 19-22 meq/L were 1.28 [95% confidence interval (95% CI), 0.84 to 1.94] and 0.91 (95% CI, 0.65 to 1.26), respectively, in children with nonglomerular disease. In children with glomerular disease, adjusted hazard ratios associated with bicarbonate level ≤18 meq/L and bicarbonate 19-22 meq/L were 2.16 (95% CI, 1.05 to 4.44) and 1.74 (95% CI, 1.07 to 2.85), respectively. Resolution of low bicarbonate was associated with a lower risk of CKD progression compared with persistently low bicarbonate (≤22 meq/L).

CONCLUSIONS

In children with glomerular disease, low bicarbonate was linked to a higher risk of CKD progression. Resolution of low bicarbonate was associated with a lower risk of CKD progression. Fewer than one half of all children with low bicarbonate reported treatment with alkali therapy. Long-term studies of alkali therapy's effect in patients with pediatric CKD are needed.

Correction to: Mode of initial renal replacement therapy and transplant outcomes in the chronic kidney disease in children (CKiD) study

The original version of this article unfortunately contained a mistake.

Mode of initial renal replacement therapy and transplant outcomes in the chronic kidney disease in children (CKiD) study

BACKGROUND

Kidney transplant is the renal replacement therapy (RRT) of choice for children with end stage kidney disease (ESKD). Only 21.3% of children who initiate RRT receive a preemptive kidney transplant (PKT). We characterized the transition to RRT in children in the CKiD cohort including the prevalence of dialysis as first RRT vs. PKT and graft survival.

METHODS

258 children enrolled in CKiD have initiated RRT, and 202 had post-RRT initiation data collected through phone or in-person follow-up. Characteristics by first RRT modality were compared using Chi-square and Kruskal-Wallis tests. Parametric-accelerated failure time models were fit for transplantation. Graft failure was characterized using Kaplan-Meier methods and log rank tests.

RESULTS

Sixty-one percent received dialysis as first RRT modality and 39% PKT. Those with PKT were less likely to have glomerular disease and to be African-American, and had higher household-income. African-American subjects were nearly twice as likely to undergo dialysis prior to transplant. Those with a living donor and a college-educated mother had 40%-decreased odds of being dialysis experienced. Children with PKT were more likely to receive a living donor transplant. Only 5% of PKT subjects had graft failure by 4 years compared to 16% of those initially treated with dialysis (p = 0.092); however, after adjustment the effect of dialysis exposure was attenuated (p = 0.206).

CONCLUSION

CKiD subjects undergo PKT more often compared to nationally-reported rates, and are more likely to receive a kidney transplant within 1 year of starting dialysis. African-American race and lower household-income are associated with decreased access to PKT.

Association Between Chronic Kidney Disease-Mineral Bone Disease (CKD-MBD) and Cognition in Children: Chronic Kidney Disease in Children (CKiD) Study

Rationale & Objective

Chronic kidney disease (CKD) in children is associated with cognitive dysfunction that affects school performance and quality of life. The relationship between CKD-mineral and bone disorder and cognitive function in children is unknown.

Study Design

Observational study.

Participants

702 children enrolled in the Chronic Kidney Disease in Children (CKiD) Study.

Predictors

Plasma fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), calcium, phosphorus, 25 hydroxyvitamin D (25[OH]D), and 1,25 dihydroxyvitamin D (1,25[OH]₂D).

Outcomes

Neurocognitive tests of intelligence, academic achievement, and executive functions.

Analytical Approach

Linear regression models to analyze the cross-sectional associations between log₂FGF-23, 25(OH)D, 1,25(OH)₂D, PTH, calcium, and phosphorus z scores and the cognitive test scores of interest after adjustment for demographics, blood pressure, proteinuria, and kidney function.

Results

At baseline, median age was 12 (95% CI, 8.3, 15.2) years and estimated glomerular filtration rate was 54 (40.5, 67.8) mL/min/1.73 m². In fully adjusted analyses, 25(OH)D, 1,25(OH)₂D, PTH, calcium, and phosphorus z scores did not associate with cognitive test scores. In fully adjusted analyses, log₂FGF-23 was associated with abnormal test scores for attention regulation (P < 0.05); specifically, Conners' Continuous Performance Test II Errors of Omission (β = 2.3 [1.0, 3.6]), Variability (β=1.4 [0.4, -2.4]), and Hit Reaction Time (β = 1.3 [0.2, 2.4]). Children in the highest FGF-23 tertile group had 7% and 9% greater cognitive risk for Hit Reaction Time and Errors of Omission compared with those in the lowest tertile, respectively. In fully adjusted analyses, higher FGF-23 tertile was associated with increased cognitive risk (P < 0.05) for Errors of Omission (β = 0.4 [0.1, 0.7]) and Hit Reaction Time (β = 0.4 [0.1, 0.7]).

Limitations

The study does not assess the cumulative effects of FGF-23 excess on cognitive function over time. Within-population stratified analyses were not performed due to limited sample size.

Conclusions

In children with CKD, higher plasma FGF-23 level is associated with lower performance in targeted tests of executive function, specifically attention regulation, independent of glomerular filtration rate.

Computer-Aided Diagnosis of Congenital Abnormalities of the Kidney and Urinary Tract in Children Using a Multi-Instance Deep Learning Method Based on Ultrasound Imaging Data

Ultrasound images are widely used for diagnosis of congenital abnormalities of the kidney and urinary tract (CAKUT). Since a typical clinical ultrasound image captures 2D information of a specific view plan of the kidney and images of the same kidney on different planes have varied appearances, it is challenging to develop a computer aided diagnosis tool robust to ultrasound images in different views. To overcome this problem, we develop a multi-instance deep learning method for distinguishing children with CAKUT from controls based on their clinical ultrasound images, aiming to automatic diagnose the CAKUT in children based on ultrasound imaging data. Particularly, a multi-instance deep learning method was developed to build a robust pattern classifier to distinguish children with CAKUT from controls based on their ultrasound images in sagittal and transverse views obtained during routine clinical care. The classifier was built on imaging features derived using transfer learning from a pre-trained deep learning model with a mean pooling operator for fusing instance-level classification results. Experimental results have demonstrated that the multi-instance deep learning classifier performed better than classifiers built on either individual sagittal slices or individual transverse slices.

Grip strength in children with chronic kidney disease

BACKGROUND

The relationship between muscle strength and chronic kidney disease (CKD) in children is unknown. This study aims to quantify the association between grip strength (GS) and kidney function and to explore factors associated with grip strength in children and adolescents with CKD.

METHODS

We included 411 children (699 GS assessments) of the Chronic Kidney Disease in Children (CKiD) study. They were matched by age, sex, and height to a healthy control from the National Health and Nutrition Examination Survey to quantify the relationship between GS and CKD. Linear mixed models were used to identify factors associated with GS among CKD patients.

RESULTS

Median GS z-score was - 0.72 (IQR - 1.39, 0.11) among CKD patients with CKD stages 2 through 5 having significantly lower GS than CKD stage 1. Compared with healthy controls, CKiD participants had a decreased GS z-score (- 0.53 SD lower, 95% CI - 0.67 to - 0.39) independent of race/ethnicity and body mass index. Factors associated with reduced GS included longer duration of CKD, pre-pubertal status, delayed puberty, neuropsychiatric comorbidities, need of feeding support, need for alkali therapy, and hemoglobin level. Decreased GS was also associated with both a lower frequency and intensity of physical activity.

CONCLUSIONS

CKD is associated with impaired muscle strength in children independent of growth retardation and BMI. Exposure to CKD for a prolonged time is associated with impaired muscle strength. Potential mediators of the impact of CKD on muscle strength include growth retardation, acidosis, poor nutritional status, and low physical activity. Additional studies are needed to assess the efficacy of interventions targeted at these risk factors.

Prognostic Value of Ambulatory Blood Pressure Load in Pediatric CKD

BACKGROUND AND OBJECTIVES

Elevated BP load is part of the criteria for ambulatory hypertension in pediatric but not adult guidelines. Our objectives were to determine the prevalence of isolated BP load elevation and associated risk with adverse outcomes in children with CKD, and to ascertain whether BP load offers risk discrimination independently or in conjunction with mean ambulatory BPs.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We studied 533 children in the CKD in Children (CKiD) Study to determine the prevalence of normotension, isolated BP load elevation (≥25% of all readings elevated but mean BP normal), and ambulatory hypertension. We examined the association between these categories of BP control and adverse outcomes (left ventricular hypertrophy [LVH] or ESKD). We used c-statistics to determine risk discrimination for outcomes by BP load used either independently or in conjunction with other BP parameters.

RESULTS

Overall, 23% of the cohort had isolated BP load elevation, but isolated BP load elevation was not statistically significantly associated with LVH in cross-section (odds ratio, 1.8; 95% CI, 0.8 to 4.2) or time to ESKD (hazard ratio, 1.2; 95% CI, 0.7 to 2.0). In unadjusted cross-sectional analysis, every 10% higher systolic BP load was associated with 1.1-times higher odds of LVH (95% CI, 1.0 to 1.3), but discrimination for LVH was poor (c=0.61). In unadjusted longitudinal analysis, every 10% higher systolic BP load was associated with a 1.2-times higher risk of ESKD (95% CI, 1.1 to 1.2), but discrimination for ESKD was also poor (c=0.60). After accounting for mean systolic BP, systolic BP load was not statistically significantly associated with either LVH or ESKD. Findings were similar with diastolic BP load.

CONCLUSIONS

BP load does not provide additive value in discriminating outcomes when used independently or in conjunction with mean systolic BP in children with CKD.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2020_03_11_CPOD10130819.mp3.

Establishing the content validity of PROMIS Pediatric pain interference, fatigue, sleep disturbance, and sleep-related impairment measures in children with chronic kidney disease and Crohn's disease

BACKGROUND

PROMIS Pediatric patient-reported outcome measures were developed with children from the general population, and their content validity has not been established in children with chronic disease. This study was done to evaluate the content validity of the PROMIS Pediatric Pain Interference and Fatigue measures in children 8-17 years-old with Crohn's disease and the PROMIS Pediatric Fatigue, Sleep Disturbance, and Sleep-related Impairment measures for children 8-17 years-old with chronic kidney disease.

METHODS

We conducted semi-structured interviews with individuals affected by Crohn's disease and chronic kidney disease. The interviews were done to elicit children's lived experiences of the PROMIS outcomes of interest. We used deductive content analysis to contrast the participants' reports of their symptoms and impacts on daily life with existing conceptual frameworks for the PROMIS measures, each of which was developed with input from children in the general population.

RESULTS

On average, we elicited an average of 7 pain interference and 7 fatigue concepts from Crohn's disease participants (n = 37), while chronic kidney disease participants (n = 26) provided 9 concepts for fatigue, 4 for sleep disturbance, and 7 for sleep-related impairment. Concept saturation was achieved after 16-19 interviews across the four PROMIS measures. Children with these two chronic health conditions reported the same breadth and types of lived experiences as children from the development samples drawn from the general population.

CONCLUSION

The study supports the content validity of several PROMIS Pediatric measures for children with Crohn's disease and chronic kidney disease. These findings provide evidence that PROMIS Pediatric measures, developed as universally relevant patient-reported outcomes, may be more broadly applicable to children with chronic disease.

Automatic kidney segmentation in ultrasound images using subsequent boundary distance regression and pixelwise classification networks

It remains challenging to automatically segment kidneys in clinical ultrasound (US) images due to the kidneys' varied shapes and image intensity distributions, although semi-automatic methods have achieved promising performance. In this study, we propose subsequent boundary distance regression and pixel classification networks to segment the kidneys automatically. Particularly, we first use deep neural networks pre-trained for classification of natural images to extract high-level image features from US images. These features are used as input to learn kidney boundary distance maps using a boundary distance regression network and the predicted boundary distance maps are classified as kidney pixels or non-kidney pixels using a pixelwise classification network in an end-to-end learning fashion. We also adopted a data-augmentation method based on kidney shape registration to generate enriched training data from a small number of US images with manually segmented kidney labels. Experimental results have demonstrated that our method could automatically segment the kidney with promising performance, significantly better than deep learning-based pixel classification networks.

Plasma Soluble Urokinase Plasminogen Activator Receptor (suPAR) and CKD Progression in Children

RATIONALE & OBJECTIVE

Soluble urokinase plasminogen activator receptor (suPAR) is a novel biomarker associated with incident chronic kidney disease (CKD) and has been identified as an independent risk factor for CKD progression in children, although these findings remain preliminary, limited to a single point in time, and unreplicated in pediatric cohorts.

STUDY DESIGN

Prospective longitudinal cohort study.

SETTING & PARTICIPANTS

565 participants aged 1 to 16 years enrolled in the Chronic Kidney Disease in Children (CKiD) Study.

EXPOSURE

Plasma suPAR levels, categorized by quartiles, measured at study entry and a 6-month follow-up interval.

OUTCOME

CKD progression, defined as the initiation of kidney replacement therapy (dialysis or transplantation) or >50% decline in estimated glomerular filtrate rate (eGFR).

ANALYTIC APPROACH

Associations between plasma suPAR quartiles and risk for CKD progression were estimated using lognormal survival models, adjusting for potential confounders.

RESULTS

Participants in the highest suPAR quartile experienced 54% faster progression compared with the lowest quartile after adjustment for demographic and traditional CKD risk factors (P < 0.001). Addition of eGFR to the model attenuated the risk, although those in the highest quartile experienced 33% faster progression compared with the lowest quartile (P = 0.008). Plasma suPAR levels showed little change over 6 months.

LIMITATIONS

Potential for residual confounding, reliance on observational data, relatively fewer patients with higher eGFRs for subgroup analysis.

CONCLUSIONS

Higher suPAR levels are associated with shorter time to kidney replacement therapy or halving of eGFR in children with CKD. This association is attenuated slightly with inclusion of eGFR in regression modeling but remains a significant association for participants with the highest suPAR levels.

Association between day of the week and medication adherence among adolescent and young adult kidney transplant recipients

Disruption of usual routines may hinder adherence, increasing the risk of rejection. We aimed to compare weekend versus weekday medication adherence among adolescent and young adult kidney transplant recipients, hypothesizing poorer adherence on weekends. We examined data from the Teen Adherence in Kidney transplant Effectiveness of Intervention Trial (TAKE-IT). We assessed the 3-month run-in period (no intervention) and the 12-month intervention interval, considering a potential interaction between weekend/weekday and treatment group. Adherence was monitored using electronic pillboxes in participants 11-24 years followed in eight transplant centers in Canada and the United States. We used logistic regression with generalized estimating equations to estimate the association between weekends/weekdays and each of perfect taking (100% of prescribed doses taken) and timing (100% of prescribed doses taken on time) adherence. Taking (OR = 0.72 [95% CI 0.65-0.79]) and timing (OR = 0.66 [95% CI 0.59-0.74]) adherence were poorer on weekends than weekdays in the run-in (136 participants) and the intervention interval (taking OR = 0.74 [0.67-0.81] and timing OR = 0.71 [95% CI 0.65-0.77]). There was no interaction by treatment group (64 intervention and 74 control participants). Weekends represent a disruption of regular routines, posing a threat to adherence. Patients and families should be encouraged to develop strategies to maintain adherence when routines are disrupted. TAKE-IT registration number: Clinicaltrials.gov registration: NCT01356277 (May 17, 2011).

Incidence of Initial Renal Replacement Therapy Over the Course of Kidney Disease in Children

The Chronic Kidney Disease in Children Study, a prospective cohort study with data collected from 2003 to 2018, provided the first opportunity to characterize the incidence of renal replacement therapy (RRT) initiation over the life course of pediatric kidney diseases. In the current analysis, parametric generalized gamma models were fitted and extrapolated for RRT overall and by specific treatment modality (dialysis or preemptive kidney transplant). Children were stratified by type of diagnosis: nonglomerular (mostly congenital; n = 650), glomerular–hemolytic uremic syndrome (HUS; n = 49), or glomerular–non-HUS (heterogeneous childhood onset; n = 216). Estimated durations of time to RRT after disease onset for 99% of the nonglomerular and glomerular–non-HUS groups were 42.5 years (95% confidence interval (CI): 31.0, 54.1) and 25.4 years (95% CI: 14.9, 36.0), respectively. Since onset for the great majority of children in the nonglomerular group was congenital, disease duration equated with age. A simulation-based estimate of age at RRT for 99% of the glomerular population was 37.9 years (95% CI: 33.6, 63.2). These models performed well in cross-validation. Children with glomerular disease received dialysis earlier and were less likely to have a preemptive kidney transplant, while the timing and proportions of dialysis and transplantation were similar for the nonglomerular group. These diagnosis-specific estimates provide insight into patient-centered prognostic information and can assist in RRT planning efforts for children with moderate-to-severe kidney disease who are receiving regular specialty care.

Using Electronic Health Record Data to Rapidly Identify Children with Glomerular Disease for Clinical Research

BACKGROUND

The rarity of pediatric glomerular disease makes it difficult to identify sufficient numbers of participants for clinical trials. This leaves limited data to guide improvements in care for these patients.

METHODS

The authors developed and tested an electronic health record (EHR) algorithm to identify children with glomerular disease. We used EHR data from 231 patients with glomerular disorders at a single center to develop a computerized algorithm comprising diagnosis, kidney biopsy, and transplant procedure codes. The algorithm was tested using PEDSnet, a national network of eight children's hospitals with data on >6.5 million children. Patients with three or more nephrologist encounters (n=55,560) not meeting the computable phenotype definition of glomerular disease were defined as nonglomerular cases. A reviewer blinded to case status used a standardized form to review random samples of cases (n=800) and nonglomerular cases (n=798).

RESULTS

The final algorithm consisted of two or more diagnosis codes from a qualifying list or one diagnosis code and a pretransplant biopsy. Performance characteristics among the population with three or more nephrology encounters were sensitivity, 96% (95% CI, 94% to 97%); specificity, 93% (95% CI, 91% to 94%); positive predictive value (PPV), 89% (95% CI, 86% to 91%); negative predictive value, 97% (95% CI, 96% to 98%); and area under the receiver operating characteristics curve, 94% (95% CI, 93% to 95%). Requiring that the sum of nephrotic syndrome diagnosis codes exceed that of glomerulonephritis codes identified children with nephrotic syndrome or biopsy-based minimal change nephropathy, FSGS, or membranous nephropathy, with 94% sensitivity and 92% PPV. The algorithm identified 6657 children with glomerular disease across PEDSnet, ≥50% of whom were seen within 18 months.

CONCLUSIONS

The authors developed an EHR-based algorithm and demonstrated that it had excellent classification accuracy across PEDSnet. This tool may enable faster identification of cohorts of pediatric patients with glomerular disease for observational or prospective studies.

Change in Dyslipidemia with Declining Glomerular Filtration Rate and Increasing Proteinuria in Children with CKD

BACKGROUND AND OBJECTIVES

Dyslipidemia, a risk factor for cardiovascular disease, is common in CKD but its change over time and how that change is influenced by concurrent progression of CKD have not been previously described.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the CKD in Children study we prospectively followed children with progressive CKD and utilized multivariable, linear mixed-effects models to quantify the longitudinal relationship between within-subject changes in lipid measures (HDL cholesterol, non-HDL cholesterol, triglycerides) and within-subject changes in GFR, proteinuria, and body mass index (BMI).

RESULTS

A total of 508 children (76% nonglomerular CKD, 24% glomerular CKD) had 2-6 lipid measurements each, with a median follow-up time of 4 (interquartile range [IQR], 2.1-6.0) years. Among children with nonglomerular CKD, dyslipidemia was common at baseline (35%) and increased significantly as children aged; 43% of children with glomerular CKD had dyslipidemia at baseline and demonstrated persistent levels as they aged. Longitudinal increases in proteinuria were independently associated with significant concomitant increases in non-HDL cholesterol (nonglomerular: 4.9 [IQR, 3.4-6.4] mg/dl; glomerular: 8.5 [IQR, 6.0-11.1] mg/dl) and triglycerides (nonglomerular: 3% [IQR, 0.8%-6%]; glomerular: 5% [IQR, 0.6%-9%]). Decreases in GFR over follow-up were significantly associated with concomitant decreases of HDL cholesterol in children with nonglomerular CKD (-1.2 mg/dl; IQR, -2.1 to -0.4 mg/dl) and increases of non-HDL cholesterol in children with glomerular CKD (3.9 mg/dl; IQR, 1.4-6.5 mg/dl). The effects of increased BMI also affected multiple lipid changes over time. Collectively, glomerular CKD displayed stronger, deleterious associations between within-subject change in non-HDL cholesterol (9 mg/dl versus 1.2 mg/dl; P<0.001) and triglycerides (14% versus 3%; P=0.004), and within-subject change in BMI; similar but quantitatively smaller differences between the two types of CKD were noted for associations of within-subject change in lipids to within-subject change in GFR and proteinuria.

CONCLUSIONS

Dyslipidemia is a common and persistent complication in children with CKD and it worsens in proportion to declining GFR, worsening proteinuria, and increasing BMI.

Environmental lead exposure is associated with neurocognitive dysfunction in children with chronic kidney disease

BACKGROUND

Environmental lead exposure is associated with cognitive impairment in healthy children, with deficits seen in intelligence quotient (IQ), attention, and behavior. Neurocognitive dysfunction is also a well-described complication among children with chronic kidney disease (CKD). The objective was to evaluate the association between blood lead levels (BLL) and performance on neurocognitive assessments in a cohort of children with CKD.

METHODS

Cross-sectional study of children with mild to moderate CKD from the Chronic Kidney Disease in Children (CKiD) multicenter prospective cohort study. The primary exposure was BLL. The primary outcome was performance on age-specific neurocognitive assessments evaluating IQ, executive functioning, attention, hyperactivity, and behavior. Multivariable linear regression was used to evaluate the association between BLL and neurocognitive performance, adjusted for key sociodemographic and clinical variables.

RESULTS

A total of 412 subjects were included with median age 15.4 years, median estimated GFR 39 mL/min/1.73², median BLL 1.2 mcg/dL, and median IQ score 99. In multivariable linear regression, higher BLL was associated with significantly lower IQ score (- 2.1 IQ points for every 1-mcg/dL increase in BLL, p = 0.029). Higher BLL was associated with worse scores on the Conners' Continuous Performance Test II Variability T-Score, a measure of inattention (+ 1.8 T-Score points for every 1-mcg/dL increase in BLL, p = 0.033).

CONCLUSIONS

Low-level lead exposure is associated with significantly lower IQ and more inattention in children with CKD, a population already at high risk for neurocognitive dysfunction. Universal screening for elevated BLL should be considered for all children with CKD at age 12-24 months.

Multi-instance Deep Learning with Graph Convolutional Neural Networks for Diagnosis of Kidney Diseases Using Ultrasound Imaging

Ultrasound imaging (US) is commonly used in nephrology for diagnostic studies of the kidneys and lower urinary tract. However, it remains challenging to automate the disease diagnosis based on clinical 2D US images since they provide partial anatomic information of the kidney and the 2D images of the same kidney may have heterogeneous appearance. To overcome this challenge, we develop a novel multi-instance deep learning method to build a robust classifier by treating multiple 2D US images of each individual subject as multiple instances of one bag. Particularly, we adopt convolutional neural networks (CNNs) to learn instance-level features from 2D US kidney images and graph convolutional networks (GCNs) to further optimize the instance-level features by exploring potential correlation among instances of the same bag. We also adopt a gated attention-based MIL pooling to learn bag-level features using full-connected neural networks (FCNs). Finally, we integrate both instance-level and bag-level supervision to further improve the bag-level classification accuracy. Ablation studies and comparison results have demonstrated that our method could accurately diagnose kidney diseases using ultrasound imaging, with better performance than alternative state-of-the-art multi-instance deep learning methods.

The effect of transfer to adult transplant care on kidney function and immunosuppressant drug level variability in pediatric kidney transplant recipients

Adolescent age at time of transplant has been recognized as a risk factor for renal allograft loss. Increased risk for graft failure may persist from adolescence to young adulthood. Transfer of care is hypothesized as a risk factor for non-adherence and graft loss. We explored whether kidney allograft function declined at an accelerated rate after transfer of care to adult transplant centers and whether coefficient of variation of tacrolimus (CV TAC) trough levels predicted allograft loss. Single-center, retrospective chart review was performed for pediatric kidney transplant recipients who received transplants between 1999 and 2011. Change in eGFR pre- and post-transfer was performed via a linear mixed-effects model. CV TAC was calculated in transplant recipients with TAC data pre- and post-transfer. t test was performed to determine the difference between means of CV TAC in subjects with and without allograft loss following transfer of care. Of the 138 subjects who transferred to adult care, 47 subjects with data pre- and post-transfer demonstrated a decrease in the rate of eGFR decline post-transfer from 8.0 mL/min/1.73 m² per year to 2.1 mL/min/1.73 m² per year, an ~80% decrease in eGFR decline post-transfer (P = 0.01). Twenty-four subjects had CV TAC data pre- and post-transfer of care. Pretransfer CV TAC for subjects with allograft loss post-transfer was significantly higher than in subjects without allograft loss (49% vs 26%, P < 0.05). Transfer of care was not independently associated with acceleration in eGFR decline. CV TAC may aid in identifying patients at risk for allograft loss post-transfer.

Depression and neurocognitive dysfunction in pediatric and young adult chronic kidney disease

BACKGROUND

Depression affects 7-35% of children with chronic kidney disease (CKD), and in adults with CKD, the presence of depression links to poorer medical outcomes, social functioning difficulties, and neurocognitive impairments. The relationship between depression and neurocognitive function in youth with CKD is unclear. We sought to identify factors associated with depression in youth with CKD and to determine whether depression affects neurocognitive performance.

METHODS

We conducted cross-sectional analyses in 71 CKD and 64 control participants aged 8 to 25 years who completed depression inventories and neurocognitive assessments as part of the Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with CKD Study. In the CKD group, multivariable logistic regression analysis determined associations between clinical and demographic factors and depression. In the full study cohort, multivariable linear regression analyses, including an interaction term between CKD status and depression evaluated the effect of depression on 11 neurocognitive outcome domains.

RESULTS

Obesity significantly associated with depression in the CKD group (OR 10.25, P = 0.01). In adjusted analyses, depressed youth with CKD scored worse than non-depressed CKD participants by 0.6-1.0 standard deviations in 5 neurocognitive domains: attention, visual memory, visual-spatial, visual working memory, and problem solving.

CONCLUSIONS

CKD youth with obesity are more likely to be depressed, and those who are depressed exhibit worse neurocognitive performance. Depression may represent a therapeutic target to improve neurocognitive performance in youth with CKD.

Estimated kidney function in children and young adults with spina bifida: A retrospective cohort study

AIMS

Current estimated glomerular filtration rate (eGFR) equations may be inaccurate in patients with spina bifida (SB) because of reduced muscle mass and stature. Cross-sectional and longitudinal variability of eGFR were analyzed in these patients across multiple equations, hypothesizing greater variability in creatinine-based than cystatin-C (Cys-C)-based equations.

METHODS

This retrospective cohort study included children (age, 1-17.9 years) and adults (≥18 years) with SB from 2002-2017 at a large SB clinic. Those without all data needed to calculate eGFR were excluded. Four pediatric and three adult eGFR equations were compared for cross-sectional outcomes of eGFR and elevated office blood pressures using chronic kidney disease (CKD) stage classification, and for longitudinal outcome of eGFR slope over time using covariance pattern models accounting for repeated measures.

RESULTS

One hundred and eighty two children and 75 adults had greater than or equal to 1 set of data measurements; 118 and 52, respectively, had greater than or equal to 2 sets. The pediatric bedside Schwartz equation had the highest median eGFR and coefficient of variation. CKD stage classification by eGFR showed large differences across equations in children, with rates of eGFR < 60 and <90 ml/min/1.73 m² ranging from 2%-9% and 5%-69%, respectively. Only one equation showed a significant inverse association between eGFR and blood pressure. Longitudinally, eGFR slopes over time were different across pediatric equations (P < .001) but not adult equations. The bedside Schwartz equation had a positive eGFR slope; the other Cys-C-containing equations had negative slopes.

CONCLUSIONS

Creatinine-based equations in children with SB vary considerably from cystatin-C-containing equations in calculating both single point-in-time eGFR values and eGFR trends over time.