Kidney Disease in African American Children: Biological and Nonbiological Disparities

Kidney disease and reproductive health

Understanding the relationship between reproductive health and kidney function is important to provide holistic care for people living with kidney disease. Chronic kidney disease (CKD) has negative impacts on both male and female fertility owing to factors including inflammation, hormonal dysregulation, reduced ovarian reserve, reduced sperm quality and sexual dysfunction. However, pregnancy is achievable for most cisgender women with kidney disease, including kidney transplant recipients and patients on dialysis. CKD in pregnancy is associated with health risks to the mother and child, including increased risk of progression of kidney disease, hypertensive complications of pregnancy, and neonatal complications including fetal growth restriction, preterm birth and stillbirth. However, with appropriate pre-pregnancy counselling, fertility assessment and support, health optimization, and evidence-based antenatal care, the majority of patients will achieve a good outcome. Medication safety should be reviewed before and during pregnancy and lactation, weighing the risk of disease flare against potential adverse effects on the offspring. Important areas for further research include the optimal timing of delivery and the short- and long-term cardiovascular and renal impacts of pregnancy in patients with CKD, as well as long-term kidney and cardiovascular outcomes in their offspring.

Disparities in Access to Timely Waitlisting Among Pediatric Kidney Transplant Candidates

BACKGROUND AND OBJECTIVES

Kidney transplantation with minimal or no dialysis exposure provides optimal outcomes for children with end-stage kidney disease. We sought to understand disparities in timely access to transplant waitlisting.

METHODS

We conducted a retrospective, registry-based cohort study of candidates ages 3 to 17 added to the US kidney transplant waitlist 2015 to 2019. We defined "preemptive waitlisting" as waitlist addition before receiving dialysis and compared demographics of candidates based on preemptive status. We used competing risk regression to determine the association between preemptive waitlisting and transplantation. We then identified waitlist additions age >18 who initiated dialysis as children, thereby missing pediatric allocation prioritization, and evaluated the association between waitlisting with pediatric prioritization and transplantation.

RESULTS

Among 4506 pediatric candidates, 48% were waitlisted preemptively. Female sex, Hispanic ethnicity, Black race, and public insurance were associated with lower adjusted relative risk of preemptive waitlisting. Preemptive listing was not associated with time from waitlist activation to transplantation (adjusted hazard ratio 0.94, 95% confidence interval 0.87-1.02). Among transplant recipients waitlisted preemptively, 68% had no pretransplant dialysis, whereas recipients listed nonpreemptively had median 1.6 years of dialysis at transplant. Among 415 candidates initiating dialysis as children but waitlisted as adults, transplant rate was lower versus nonpreemptive pediatric candidates after waitlist activation (adjusted hazard ratio 0.54, 95% confidence interval 0.44-0.66).

CONCLUSIONS

Disparities in timely waitlisting are associated with differences in pretransplant dialysis exposure despite no difference in time to transplant after waitlist activation. Young adults who experience delays may miss pediatric prioritization, highlighting an area for policy intervention.

Prevalence and Risk Factors for Kidney Disease and Elevated BP in 2-Year-Old Children Born Extremely Premature

BACKGROUND AND OBJECTIVES

Extremely low gestational age neonates born <28 weeks gestation are at risk for chronic disease. We sought to describe the prevalence of kidney outcomes by gestational age and determine risk factors for their development.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Recombinant Erythropoietin for Protection of Infant Renal Disease (REPAIReD) study examined kidney outcomes of extremely low gestational age neonates enrolled in the Preterm Epo NeuroProtection Trial (PENUT) study. Kidney function, urine albumin, and BP were measured at 2-year (24±2 months) corrected gestational age. We compared outcomes across gestational age categories and evaluated associations between kidney-related outcomes and neonatal and maternal characteristics. The primary outcome was eGFR <90 ml/min per 1.73 m² (CKD); secondary outcomes were spot urine albumin-creatinine ratio ≥30 mg/g (albuminuria) and either systolic BP or diastolic BP >90th percentile for height, age, and sex.

RESULTS

A total of 832 survived to 2 years, and 565 (68%) had at least one outcome measured. Overall, 297 (53%) had one abnormal kidney outcome; 61 (18%) had an eGFR <90 ml/min per 1.73 m², 155 (36%) had albuminuria, 65 (22%) had elevated systolic BP, and 128 (44%) had elevated diastolic BP. Gestational age (odds ratio, 0.94; 95% confidence interval, 0.89 to 0.99), birth weight z-score (odds ratio, 0.92; 95% confidence interval, 0.85 to 0.98), and prenatal steroids (odds ratio, 1.23; 95% confidence interval, 1.08 to 1.39) were associated with an eGFR <90 ml/min per 1.73 m². An elevated systolic BP was associated with indomethacin use (odds ratio, 1.18; 95% confidence interval, 1.04 to 1.33) and Black race (odds ratio, 1.19; 95% confidence interval, 1.01 to 1.39); elevated diastolic BP was associated with male sex (odds ratio, 1.29; 95% confidence interval, 1.12 to 1.49), severe AKI (odds ratio, 1.24; 95% confidence interval, 1.04 to 1.48), and indomethacin use (odds ratio, 1.16; 95% confidence interval, 1.01 to 1.33).

CONCLUSIONS

Approximately 18% of extremely low gestational age neonates have CKD, 36% have albuminuria, 22% have an elevated systolic BP, and 44% have an elevated diastolic BP at 2 years of age. Gestational age, birthweight z-score, and prenatal steroids were associated with CKD. Male sex, Black race, indomethacin use, and severe AKI were associated with elevated BP.

PODCAST

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Chronic kidney disease emerging trends in children and what to do about it

Chronic Kidney disease (CKD) is a major public health problem associated with increased health costs, morbidity, and mortality. There is a 30-fold higher mortality rate and severely impaired quality of life in children with chronic kidney disease (CKD), requiring dialysis or kidney transplant compared to the aged-match general population. The early diagnosis and treatment of pediatric CKD can reverse, delay or prevent progression to advanced kidney disease. It is worth noting that CKD with rapid progression, which carries a poor prognosis, is more common in African American children. Thus, the development of a universal pediatric CKD screening program for high-risk children can be vital for social equity. The disparity in prevalence and severity of CKD is likely due to a complex interaction between biological and nonbiological risk factors that influence the development and progression of CKD in children of African descent. For example, high-risk alleles in the gene encoding for apolipoprotein L1 (APOL1) have been recognized as the most important factor in the high incidence of some chronic kidney diseases in African Americans. In this review, we will focus on the trends in the incidence of pediatric CKD and management strategies aimed at enhancing health outcomes and reducing disease progression.

Mortality Risk Factors among Infants Receiving Dialysis in the Neonatal Intensive Care Unit

OBJECTIVES

To identify risk factors associated with mortality for infants receiving dialysis in the neonatal intensive care unit (NICU).

STUDY DESIGN

In this retrospective cohort study, we extracted data from the Pediatrix Clinical Data Warehouse on all infants who received dialysis in the NICU from 1999 to 2018. Using a Cox proportional hazards model with robust SEs we estimated the mortality hazard ratios associated with demographics, birth details, medical complications, and treatment exposures.

RESULTS

We identified 273 infants who received dialysis. Median gestational age at birth was 35 weeks (interquartile values 33-37), median birth weight was 2570 g (2000-3084), 8% were small for gestational age, 41% white, and 72% male. Over one-half of the infants (59%) had a kidney anomaly; 71 (26%) infants died before NICU hospital discharge. Factors associated with increased risk of dying after dialysis initiation included lack of kidney anomalies, Black race, gestational age of <32 weeks, necrotizing enterocolitis, dialysis within 7 days of life, and receipt of paralytics or vasopressors (all P < .05).

CONCLUSION

In this cohort of infants who received dialysis in the NICU over 2 decades, more than 70% of infants survived. The probability of death was greater among infants without a history of a kidney anomaly and those with risk factors consistent with greater severity of illness at dialysis initiation.

APOL1 genotypes: Do they contribute to ethnicity-associated biological health inequalities in pregnancy?

Inferior health outcomes for people of African and Afro-Caribbean ancestry compared to those of European ancestry are well recognised. There is a disproportionate impact within these communities compared to other ethnic groups including pregnancy outcomes, hypertension, kidney disease and diabetes. The ‘Black Lives Matter’ movement has highlighted that it is imperative to examine all factors contributing to this inequity and to strive to explore multifaceted ways, including social, economic, psychological and biological to improve overall health equity. It is within this context that we discuss the novel finding of Apolipoprotein 1 genetic polymorphisms which have been identified in some populations of African ancestry. We will explore the history and evolutionary advantages of Apolipoprotein 1 polymorphisms and the pathophysiology resulting from these adaptations and examine the impact of Apolipoprotein 1 on pregnancy outcomes, the risks and benefits of screening for high-risk Apolipoprotein 1 alleles in black communities and potential treatments currently being investigated.

Pruritus Features in Children with End-Stage Renal Disease Underwent Dialysis: A Cross-Sectional Study

Objective

Evaluation of the pruritus features in children with end-stage renal disease (ESRD) who underwent dialysis at an academic tertiary pediatric dialysis center.

Methods

This cross-sectional study was conducted at an academic tertiary pediatric dialysis center, Isfahan, Iran. The reviewed medical records of the children included their characteristics, dialysis properties, and laboratory parameters. The 4-item itch questionnaire was utilized to assess distribution, severity, frequency, and associated sleeping disorders.

Results

Thirty ESRD patients with pruritus, including 23 males (76.7%) with a mean age of 11.7 ± 3.64 years, were recruited. The most common cause of CKD was nephronophthisis (23.3%). The median total score of pruritus was 5 (range: 3-15). The distribution score of pruritus was directly correlated with the age (Spearman's rho = 0.42, P = 0.02) and serum level of parathyroid hormone (PTH) (Spearman's rho = 0.42, P = 0.04). In the reduced multiple logistic regression model, the increasing level of serum calcium was associated with increased odds of having total pruritus score ≥ 5 (OR (odds ratio): 4.5; 95% CI 1.12 to 18.05). In addition, an increase in age for one year was found to be associated with 50% higher odds of having total pruritus score ≥ 5 (OR: 1.5; 95% CI 1.03 to 2.18).

Conclusion

Increased level of serum Ca and higher age were associated with increased odds of having more severe pruritus score in children.

A focus on the association of Apol1 with kidney disease in children

Individuals of African origin have an increased risk of developing various progressive chronic kidney diseases (CKD). This risk has been attributed to genetic variants (G1, G2) in apolipoprotein-L1 (APOL1) gene. In the pediatric population, especially in children affected by sickle cell disease (SCD), by human immunodeficiency virus (HIV), or with various glomerular diseases, APOL1 risk variants have been associated with the development of hypertension, albuminuria, and more rapid decline of kidney function. The present review focuses on existing APOL1-related epidemiological data in children with CKD. It also includes data from studies addressing racial disparities in CKD, the APOL1-related innate immunity, and the relationship between APOL1 and CKD and pathogenic pathways mediating APOL1-related kidney injury.

Chromogranin A pathway: from pathogenic molecule to renal disease

BACKGROUND

Chromogranin A (CHGA) is an index granin protein critical for biogenesis and exocytotic release of catecholamine storage granules. It is elevated in plasma of patients with sympathetic over-activity and kidney dysfunction. Several CHGA polymorphisms are associated with hypertensive kidney disease. Previously, we unraveled the molecular mechanism by which CHGA expression is regulated in African Americans carrying a genetic variation associated with hypertensive chronic kidney disease (CKD).

METHOD

Experimental CKD mouse model were created by 5/6th nephrectomy (Npx) using wild-type and Chga-/- knockout mouse strains to delineate the role of CHGA in CKD.

RESULT

Wild-type-Npx mice expressing Chga developed exacerbated azotemia and fibrosis as compared with their knockout-Npx counterparts. Gene expression profiling revealed downregulation of mitochondrial respiratory complexes genes consistent with maladaptive mitochondria in wild-type-Npx mice, contrasted to knockout-Npx. In healthy individuals, an inverse relationship between circulating CHGA levels and glomerular function was observed. In vitro, mesangial cells treated with CHGA-triggered nitric oxide release by a signaling mechanism involving scavenger receptor SR-A. The CHGA-treated and untreated mesangial cells displayed differential expression of cytokine, chemokine, complement, acute phase inflammatory and apoptotic pathway genes. Thus, build-up of plasma CHGA because of kidney injury served as an insult to the mesangial cells resulting in expression of genes promoting inflammation, fibrosis, and progression of CKD.

CONCLUSION

These findings improve understanding of the role of elevated CHGA in the progression of CKD and reveal novel pathways that could be exploited for therapeutic strategies in hypertensive kidney disease.

Long-term survival of children following acute peritoneal dialysis in a resource-limited setting

BACKGROUND

There is a paucity of data on long term-outcomes of children who undergo acute peritoneal dialysis (PD) in resource-limited settings. We reviewed the outcomes of children who underwent PD after 18 months of follow-up.

METHODS

We conducted a prospective cohort study in children with acute kidney injury (AKI) who underwent PD. Diagnosis of AKI was based on the 2012 Kidney Disease: Improving Global Outcomes definition. We assessed outcomes of in-hospital mortality, 18-month post-dialysis survival, factors associated with survival, and progression to chronic kidney disease (CKD).

RESULTS

Twenty-nine children with a median age of 6 (3 to 11) years underwent acute PD. In-hospital mortality was 3/29 (10.3%) and rose to 27.6% during follow-up. Seven (24.1%) children were lost to follow-up. Of the 14 remaining children, six (42.9%) experienced full recovery of renal function, while eight (57.1%) progressed to CKD. Among those who experienced full recovery, median (interquartile range) estimated glomerular filtration rate (eGFR) rose from 12.67 (7.05, 22.85) mL/min/1.73 m2 to 95.56 (64.50, 198.00) mL/min/1.73 m2, P = 0.031. No significant changes in median eGFR from baseline were observed among those who progressed to CKD (P = 0.383) or in non-survivors (P = 0.838). According to Kaplan-Meier curve analyses, 18-month survival during follow-up was 66.0% (95% CI, 45.0% to 86.5%). Age < 5 was associated with greater likelihood of survival (OR, 3.217; 95% CI, 1.240 to 8.342).

CONCLUSION

Progression of post-PD AKI to CKD occurred in more than half of survivors. Age < 5 was associated with greater likelihood of survival.

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.

Fluoride exposure and kidney and liver function among adolescents in the United States: NHANES, 2013-2016

BACKGROUND

Hepato- and nephrotoxicity of fluoride have been demonstrated in animals, but few studies have examined potential effects in humans. This population-based study examines the relationship between chronic low-level fluoride exposure and kidney and liver function among United States (U.S.) adolescents. This study aimed to evaluate whether greater fluoride exposure is associated with altered kidney and liver parameters among U.S. youth.

METHODS

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2013-2016). We analyzed data from 1983 and 1742 adolescents who had plasma and water fluoride measures respectively and did not have kidney disease. Fluoride was measured in plasma and household tap water. Kidney parameters included estimated glomerular filtration rate (calculated by the original Schwartz formula), serum uric acid, and the urinary albumin to creatinine ratio. Liver parameters were assessed in serum and included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, gamma-glutamyl transferase, and albumin. Survey-weighted linear regression examined relationships between fluoride exposure and kidney and liver parameters after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons.

RESULTS

The average age of adolescents was 15.4 years. Median water and plasma fluoride concentrations were 0.48 mg/L and 0.33 μmol/L respectively. A 1 μmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73 m2 lower estimated glomerular filtration rate (95% CI: -17.50, -3.22; p = 0.05), a 0.29 mg/dL higher serum uric acid concentration (95% CI: 0.09, 0.50; p = 0.05), and a 1.29 mg/dL lower blood urea nitrogen concentration (95%CI: -1.87, -0.70; p < 0.001). A 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen concentration (95% CI: -1.44, -0.42; p = 0.007).

CONCLUSIONS

Fluoride exposure may contribute to complex changes in kidney and liver related parameters among U.S. adolescents. As the study is cross-sectional, reverse causality cannot be ruled out; therefore, altered kidney and/or liver function may impact bodily fluoride absorption and metabolic processes.