Pubertal luteinizing hormone levels in children with chronic kidney disease and association with change in glomerular filtration rate

BACKGROUND

Children with chronic kidney disease (CKD) are at risk for abnormalities in pubertal development. We aimed to describe the timing of pubertal onset by luteinizing hormone (LH) levels and the association between hormonal onset of puberty with changes in GFR.

METHODS

Data from the Chronic Kidney Disease in Children (CKiD) study were collected prospectively. GFR was estimated at annual visits and measured by iohexol clearance every other year. LH was measured from stored repository serum samples in a nested sample of 124 participants. Hormonal onset of puberty was defined as LH level greater than or equal to 0.3 IU/L. A mixed effects model with random intercepts and slopes was used to compare the slope of decline of GFR before and after hormonal onset of puberty. The model was adjusted for age, glomerular disease diagnosis, baseline proteinuria on the log scale, and BMI.

RESULTS

Median age at hormonal onset of puberty was 9.9 years (IQR 8.1, 11.9) in girls and 10.2 years (IQR 9.2, 11.0) in boys. The mixed effects model showed faster decline in both estimated GFR and measured GFR in boys after hormonal onset of puberty (p < 0.001), and a similar but attenuated accelerated estimated GFR decline was observed for girls with no difference for measured GFR.

CONCLUSIONS

LH levels in the post-pubertal range were observed prior to clinical manifestations of puberty in children with CKD. Hormonal onset of puberty was associated with faster decline in GFR, particularly among boys with CKD.

Epidemiology and Risk Factors for Hemodialysis Access-Associated Infections in Children: A Prospective Cohort Study From the SCOPE Collaborative

RATIONALE & OBJECTIVE

Infections cause significant morbidity and mortality for children receiving maintenance hemodialysis (HD). The Standardizing Care to Improve Outcomes in Pediatric End-Stage Kidney Disease (SCOPE) Collaborative is a quality-improvement initiative aimed at reducing dialysis-associated infections by implementing standardized care practices. This study describes patient-level risk factors for catheter-associated bloodstream infections (CA-BSIs) and examines the association between dialysis center-level compliance with standardized practices and risk of CA-BSI.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Children enrolled in SCOPE between June 2013 and July 2019.

EXPOSURES

Data were collected on patient characteristics and center-level compliance with HD catheter care practices across the study period. Centers were categorized as consistent, dynamic (improved compliance over the study period), or inconsistent performers based on frequency of compliance audit submission and changes in compliance with HD care practices over time.

OUTCOME

CA-BSIs.

ANALYTICAL APPROACH

Generalized linear mixed models were used to evaluate (1) patient-level risk factors for CA-BSI and (2) associations between change in center-level compliance and CA-BSIs.

RESULTS

The cohort included 1,277 children from 35 pediatric dialysis centers; 1,018 (79.7%) had a catheter and 259 (20.3%) had an arteriovenous fistula or graft. Among children with a catheter, mupirocin use at the catheter exit site was associated with an increased rate of CA-BSIs (rate ratio [RR], 4.45; P = 0.004); the use of no antibiotic agent at the catheter exit site was a risk factor of borderline statistical significance (RR, 1.79; P = 0.05). Overall median compliance with HD catheter care practices was 87.5% (IQR, 77.3%-94.0%). Dynamic performing centers showed a significant decrease in CA-BSI rates over time (from 2.71 to 0.71 per 100 patient-months; RR, 0.98; P < 0.001), whereas no significant change in CA-BSI rates was detected among consistent or inconsistent performers.

LIMITATIONS

Lack of data on adherence to HD care practices on the individual patient level.

CONCLUSIONS

Improvement in compliance with standardized HD care practices over time may lead to a reduction in dialysis-associated infections.

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.

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.

Tubulointerstitial Nephritis

Tubulointerstitial nephritis (TIN) is a cause of acute kidney injury in children characterized histologically by an inflammatory cell infiltrate in the kidney interstitium. The most common causes of TIN in children include medications, infections, inflammatory disorders, and genetic conditions. TIN typically presents with nonoliguric acute kidney injury and may be associated with systemic symptoms, including fever, rash, and eosinophilia. The long-term prognosis is generally favorable, with full kidney recovery; however, some patients may develop progressive chronic kidney disease. Immunosuppressive therapy may be indicated for severe or prolonged disease.

Outcomes Among Children Who Received a Kidney Transplant in the United States From a Hepatitis B Core Antibody-Positive Donor, 1995-2010

BACKGROUND

Accepting kidneys for transplant from donors with a history of hepatitis B virus infection may increase the availability of organs for those with end-stage kidney disease. In adult recipients, kidney transplants from hepatitis B virus core antibody-positive donors have resulted in favorable graft and patient survival rates. However, pediatric organ transplant recipients have developing immune systems and a higher risk of infectious complications than adults. Accordingly, little is known about the outcomes of children who have received a kidney transplant from a hepatitis B virus core antibody-positive donor.

METHODS

We included 11 898 children ≤18 years of age who received a first kidney transplant in the United States between January 1, 1995, and December 31, 2010, and who were recorded in the Scientific Registry of Transplant Recipients. We examined differences in graft and patient survival rates among children who received a kidney transplant from a hepatitis B virus core antibody-positive donor.

RESULTS

There were 199 children (1.7%) who received a kidney transplant from a hepatitis B virus core antibody-positive donor. More than 80% of these transplants occurred in recipients who were hepatitis B virus core antibody and surface antigen negative. After a median follow-up of 7.9 years, there were no significant differences in the adjusted graft (hazard ratio [HR], 1.03 [95% confidence interval (CI), 0.80-1.31]) or patient (HR, 1.12 [95% CI, 0.73-1.73]) survival rates according to donor core antibody status.

CONCLUSIONS

It may be acceptable, on a case-by-case basis, to consider hepatitis B virus core antibody-positive donors for kidney transplants to seroprotected children with end-stage kidney disease.

Cardiovascular Disease Risk Factors and Left Ventricular Hypertrophy in Girls and Boys With CKD

BACKGROUND AND OBJECTIVES

Prior studies suggested that women with CKD have higher risk for cardiovascular disease (CVD) and mortality than men, although putative mechanisms for this higher risk have not been identified. We assessed sex differences in (1) CVD risk factors and left ventricular hypertrophy (LVH), and (2) the relationship of left ventricular mass (LVM) with different measures of body size in children with CKD.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

The study population comprised 681 children with CKD from the Chronic Kidney Disease in Children cohort, contributing 1330 visits. CVD risk factors were compared cross-sectionally by sex. LVH was defined as LVM/height2.7 >95th percentile and LVM relative to estimated lean body mass (eLBM) >95th percentile for age and sex. Differences in LVM by sex were assessed by adjusting for age, weight, height, and eLBM using bivariate and multivariate regression models.

RESULTS

Girls were less likely to have uncontrolled hypertension (26% versus 38%, P=0.001), had lower diastolic BP z-scores (+0.3 versus +0.6, P=0.001), and had lower prevalence of high triglycerides (38% versus 47%, P=0.03) compared with boys. When LVH was defined by LVM indexed to height, girls had higher prevalence of LVH (16% versus 9%, P=0.01); when LVH was defined by LVM relative to eLBM, prevalence of LVH was similar between girls and boys (18% versus 17%, P=0.92). In regression models adjusting for eLBM, no sex differences in LVM were observed.

CONCLUSIONS

Despite lack of increased prevalence of CVD risk factors, indexing LVM to height showed a higher proportion of LVH among girls, while estimates of LVH based on eLBM showed no sex differences. Indexing LVM to eLBM may be an alternative to height indexing in children with CKD.

Post-streptococcal glomerulonephritis associated with atypical hemolytic uremic syndrome: to treat or not to treat with eculizumab?

A 7-year-old male with poststreptococcal glomerulonephritis (PSGN) developed hemolytic uremic syndrome (HUS) and achieved remission. He was treated with eculizumab for 1 year. The eculizumab was discontinued and the patient remained in remission. This is the 10th reported case of PSGN associated with HUS. The histopathological feature observed at the 1-year follow-up was indistinguishable from the expected findings in an individual with healed PSGN without associated HUS. The relatively good prognosis in most prior cases and the absence of any reported recurrences strongly suggest that this form of atypical HUS does not warrant long-term eculizumab therapy.

Heart Retransplant Recipients Have Better Survival With Concurrent Kidney Transplant Than With Heart Retransplant Alone

BACKGROUND

Heart retransplant (HRT) recipients represent a growing number of transplant patients. The impact of concurrent kidney transplants (KTs) in this population has not been well studied. We tested the hypothesis that recipients of HRT with concurrent KT (HRT-KT) would have worse survival than recipients of HRT alone.

METHODS AND RESULTS

A retrospective analysis of the United Network of Organ Sharing database was performed for all patients undergoing HRT from 1987 to 2011. There were 1660 HRT patients, of which 116 (7%) received concurrent KT. Those who received HRT-KT had older age, longer wait-list time, worse kidney function, and more known diabetes. Survival among recipients of HRT-KT was significantly better than that of recipients of HRT alone (P=0.005). A subgroup of 323 HRT patients with severe kidney dysfunction (estimated glomerular filtration rate <30 mL/min per 1.73 m(2) or on dialysis) was studied in more detail, and 76 (24%) received concurrent KT. Those on dialysis at the time of HRT had better survival with versus without concurrent KT (P<0.0001). On multivariable analysis, concurrent KT was independently associated with better outcomes for all patients with HRT and for the subgroup of patients with severe kidney dysfunction.

CONCLUSIONS

Recipients of HRT-KT have better survival than recipients of HRT alone. Further research is needed to determine which HRT patients may benefit the most from concurrent KT.

Executive Functioning in Children, Adolescents, and Young Adults with Chronic Kidney Disease

OBJECTIVE

To compare behavior ratings of executive functioning in individuals with chronic kidney disease (CKD), using the Behavior Rating Inventory for Executive Functions (BRIEF), with a typically developing comparison group and to examine the correlation between disease severity and ratings of executive functioning.

METHODS

Participants included 92 individuals with CKD (eGFR < 90 mL/min per 1.73 m), aged 8 to 25 years, recruited from nephrology clinics in both hospital and community settings. The disease severity ranged from CKD Stage II to V. The BRIEF was completed by parents for individuals younger than 18 years of age and the BRIEF-Adult was completed by individuals who were older than 18.

RESULTS

For individuals with CKD younger than 18 years of age, the parent-reported BRIEF revealed significant group differences when compared with controls on the Metacognition Index and the individual scales of Initiate, Working Memory, and Plan/Organize. A large proportion of individuals with CKD were rated as being at-risk for executive dysfunction. For the individuals of 18 years of age and older, there were no significant group differences. The relationship between BRIEF ratings and disease severity was limited to a few scales across both versions of the BRIEF.

CONCLUSION

This study supported the presence of executive dysfunction through a parent report, although the level of impairment was mild and its association with disease severity was related to select executive functions. Few difficulties were reported by older adolescents and young adults with CKD. It will be important for developmental-behavioral pediatricians to be cognizant of the level and pattern of executive function capabilities in their patients with CKD, and possible discrepancies with parent reports, so as to facilitate their management and transition planning.

Neurocognitive Dysfunction in Children, Adolescents, and Young Adults With CKD

BACKGROUND

Neurocognitive dysfunction is a known complication in children with chronic kidney disease (CKD). However, less is known about putative mechanisms or modifiable risk factors. The objective of this study was to characterize and determine risk factors for cognitive dysfunction in children, adolescents, and young adults with CKD compared with controls.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

The Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults With Chronic Kidney Disease (NiCK) Study included 90 individuals aged 8 to 25 years with CKD compared with 70 controls.

PREDICTORS

CKD versus control, estimated glomerular filtration rate (eGFR), ambulatory blood pressure.

OUTCOMES

Performance on neurocognitive assessment with relevant tests grouped into 11 domains defined a priori by expert opinion. Results of tests were converted to age-normalized z scores.

MEASUREMENTS

Each neurocognitive domain was analyzed through linear regression, adjusting for eGFR and demographic and clinical variables. For domains defined by multiple tests, the median z score of tests in that domain was used.

RESULTS

We found significantly poorer performance in multiple areas of neurocognitive function among individuals with CKD compared with controls. Particular deficits were seen in domains related to attention, memory, and inhibitory control. Adjusted for demographic and clinical factors, we found lower performance in multiple domains with decreasing eGFRs (attention: β=0.053, P=0.02; visual spatial: β=0.062, P=0.02; and visual working memory: β=0.069, P=0.04). Increased diastolic load and decreased diastolic nocturnal dipping on ambulatory blood pressure monitoring were independently associated with impairments in neurocognitive performance.

LIMITATIONS

Unable to assess changes in neurocognitive function over time, and neurocognitive tests were grouped into predetermined neurocognitive domains.

CONCLUSIONS

Lower eGFR in children, adolescents, and young adults is associated with poorer neurocognitive performance, particularly in areas of attention, memory, and inhibitory control. Hypertension identified on ambulatory blood pressure monitoring may be an important risk factor, illustrating that neurocognitive function is an area of target-organ damage in CKD.

The Risk of End-Stage Renal Disease Among Living Donor Liver Transplant Recipients in the United States

Since initiation of model for end-stage liver disease (MELD)-based allocation for liver transplantation, the risk of posttransplant end-stage renal disease (ESRD) has increased. Recent US data have demonstrated comparable, if not superior survival, among recipients of living donor liver transplants (LDLT) when compared to deceased donor liver transplant (DDLT) recipients. However, little is known about the incidence of ESRD post-LDLT. We analyzed linked Scientific Registry of Transplant Recipients (SRTR) and US Renal Data System (USRDS) data of first-time liver-alone transplant recipients from February 27, 2002 to March 1, 2011, and restricted the cohort to recipients with a laboratory MELD score ≤25 not on dialysis prior to transplantation, in order to evaluate the incidence of ESRD post-LDLT, and to compare the incidence among LDLT versus DDLT recipients. There were 28 707 DDLT and 1917 LDLT recipients included in the analyses. The 1-, 3- and 5-year unadjusted risk of ESRD was 1.7%, 2.9% and 3.4% in LDLT recipients, compared with 1.5%, 3.0% and 4.8% in DDLT recipients (p > 0.05), respectively. In multivariable competing risk Cox regression models, there was no association between receiving an LDLT and risk of ESRD (sub-hazard ratio: 0.99, 95% CI: 0.77-1.26, p = 0.92). In conclusion, the incidence of ESRD post-LDLT in the United States is low, and there are no significant differences among LDLT and DDLT recipients with MELD scores ≤25 at transplantation.

Design and methods of the NiCK study: neurocognitive assessment and magnetic resonance imaging analysis of children and young adults with chronic kidney disease

Background

Chronic kidney disease is strongly linked to neurocognitive deficits in adults and children, but the pathophysiologic processes leading to these deficits remain poorly understood. The NiCK study (Neurocognitive Assessment and Magnetic Resonance Imaging Analysis of Children and Young Adults with Chronic Kidney Disease) seeks to address critical gaps in our understanding of the biological basis for neurologic abnormalities in chronic kidney disease. In this report, we describe the objectives, design, and methods of the NiCK study.

Design/methods

The NiCK Study is a cross-sectional cohort study in which neurocognitive and neuroimaging phenotyping is performed in children and young adults, aged 8 to 25 years, with chronic kidney disease compared to healthy controls. Assessments include (1) comprehensive neurocognitive testing (using traditional and computerized methods); (2) detailed clinical phenotyping; and (3) multimodal magnetic resonance imaging (MRI) to assess brain structure (using T1-weighted MRI, T2-weighted MRI, and diffusion tensor imaging), functional connectivity (using functional MRI), and blood flow (using arterial spin labeled MRI). Primary analyses will examine group differences in neurocognitive testing and neuroimaging between subjects with chronic kidney disease and healthy controls. Mechanisms responsible for neurocognitive dysfunction resulting from kidney disease will be explored by examining associations between neurocognitive testing and regional changes in brain structure, functional connectivity, or blood flow. In addition, the neurologic impact of kidney disease comorbidities such as anemia and hypertension will be explored. We highlight aspects of our analytical approach that illustrate the challenges and opportunities posed by data of this scope.

Discussion

The NiCK study provides a unique opportunity to address key questions about the biological basis of neurocognitive deficits in chronic kidney disease. Understanding these mechanisms could have great public health impact by guiding screening strategies, delivery of health information, and targeted treatment strategies for chronic kidney disease and its related comorbidities.

Kidney and liver transplantation in children with fibrocystic liver-kidney disease: data from the US Scientific Registry of Transplant Recipients: 1990-2010

The natural history and survival of children with fibrocystic liver-kidney disease undergoing solid organ transplantation have infrequently been described. We report outcomes in a cohort of US children with fibrocystic liver-kidney disease receiving solid organ transplants over 20 yr. Retrospective cohort study of pediatric transplant recipients with diagnoses of fibrocystic liver-kidney disease from 1/1990 to 3/2010, using data from the SRTR. Subjects were categorized by the first transplanted organ: LT, KT, or SLK. Primary outcomes were death, re-transplant, transplant of the alternate organ, or initiation of dialysis. Seven hundred and sixteen subjects were transplanted in this period. Median age at first transplant was 9.7 yr. Of the LT, 14 (19%) required a second liver transplant at median of 0.2 yr, and five (7%) required kidney transplant or dialysis at a median of 9.0 yr. Of the KT, 188 (31%) required a second kidney transplant or dialysis at a median of 5.9 yr. Twenty-nine (5%) subsequently received liver transplant at a median of 6.0 yr. Among patients in this registry, far more children underwent kidney than liver transplants. The risk of subsequently needing transplantation of an alternate organ was low.

Renal function assessment in child and adolescent heart transplant recipients during routine cardiac catheterization

CKD identification after pediatric heart transplantation (PHT) is limited by inaccuracies in estimates of GFR. We hypothesized that GFR can be measured by a modified iohexol clearance protocol in PHT recipients and that the CKiD formula provides a better estimate of GFR than other estimating equations. A cross-sectional study of PHT recipients, ages 2-18 yr, undergoing coronary angiography was undertaken. The angiography dose of iohexol was divided by the area under the curve from three iohexol levels post-infusion to calculate GFR. Agreement between iGFR and multiple estimating equations (eGFR) was assessed. In 31 subjects, median age was 15.0 yr (IQR 7.6, 16.6). Mean iGFR was 93.8 (s.d. 22.5) mL/min/1.73 m(2) ; 16 (52%) had an iGFR <90 mL/min/1.73 m(2) . The full CKiD formula (mean eGFR 88.9, s.d. 14.9) had low bias (-5.0), narrowest 95% limits of agreement (-42.0, 32.1), highest 30% (94%) and 10% (52%) accuracy, and highest correlation coefficient (0.576) relative to iGFR. We describe a novel modified iohexol clearance method to assess GFR after PHT. Over half of the cohort had an iGFR <90, suggesting CKD. The full CKiD formula performs best with respect to bias, accuracy, and correlation.

Donation after cardiac death liver transplantation is associated with increased risk of end-stage renal disease

Limited organ supply has led to greater use of liver allografts with higher donor risk indices (DRI) and/or donated after cardiac death (DCD). DCD status is associated with acute kidney injury after liver transplantation; however, less is known about the association between donor quality and end-stage renal disease (ESRD). Using SRTR data, we assembled a cohort of liver transplant recipients from 2/2002 to 12/2010. We fit multivariable Cox regression models for ESRD. Model 1 included total DRI; model 2 included components of DRI, including DCD, as separate variables. Forty thousand four hundred and sixty-three liver transplant recipients were included. Median DRI was 1.40 (IQR 1.14, 1.72); 1822 (5%) received DCD livers. During median follow-up of 3.93 years, ESRD occurred in 2008 (5%) and death in 11 075 (27%) subjects. There was a stepwise increase in ESRD risk with higher DRI (DRI ≥1.14 and <1.40: HR 1.17, P = 0.06; DRI ≥1.40 and <1.72: HR 1.29, P = 0.003; DRI ≥1.72: HR 1.39, P < 0.001, compared with DRI <1.14). Adjusting for DRI components separately, DCD status was most strongly associated with ESRD (HR 1.40, P = 0.008). Higher DRI is associated with ESRD after liver transplantation, driven in part by DCD status. Donor quality is an important predictor of long-term renal outcomes in liver transplant recipients.

Nephrotic syndrome associated with tyrosine kinase inhibitors for pediatric malignancy: case series and review of the literature

BACKGROUND

Tyrosine kinase (TK) inhibitors are increasingly being used to treat a variety of pediatric malignancies. Reports in adult patients describe a range of effects of TK inhibitors on the kidney, including hypertension, proteinuria, acute kidney injury, and thrombotic microangiopathy (TMA); however, there are only a few reports of TK-inhibitor-associated nephrotic syndrome.

METHODS

We report four pediatric patients with various malignancies (chronic myelogenous leukemia, acute lymphoblastic leukemia, and glioma/renal cell carcinoma) who developed nephrotic syndrome during treatment with TK inhibitors (imatinib, sunitinib, dasatinib, and quizartinib). One of the four patients also had clinical features of TMA.

RESULTS

Three of the four patients achieved complete remission of nephrotic syndrome with discontinuation of the TK inhibitor and have had no additional nephrotic syndrome relapses to date. The temporal relationship of nephrotic syndrome onset to TK-inhibitor therapy and resolution of nephrotic syndrome with cessation of therapy strongly imply an association in these patients.

CONCLUSIONS

TK inhibitors are important therapies in pediatric cancer, and their use is expanding. Nephrotic syndrome with or without features of TMA is a potential complication of these therapies in children.

Current treatment of atypical hemolytic uremic syndrome

Tremendous advances have been made in understanding the pathogenesis of atypical Hemolytic Uremic Syndrome (aHUS), an extremely rare disease. Insights into the molecular biology of aHUS resulted in rapid advances in treatment with eculizumab (Soliris(®), Alexion Pharmaceuticals Inc.). Historically, aHUS was associated with very high rates of mortality and morbidity. Prior therapies included plasma therapy and/or liver transplantation. Although often life saving, these were imperfect and had many complications. We review the conditions included under the rubric of aHUS: S. pneumoniae HUS (SpHUS), inborn errors of metabolism, and disorders of complement regulation, emphasizing their differences and similarities. We focus on the clinical features, diagnosis, and pathogenesis, and treatment of aHUS that results from mutations in genes encoding alternative complement regulators, SpHUS and HUS associated with inborn errors of metabolism. Mutations in complement genes, or antibodies to their protein products, result in unregulated activity of the alternate complement pathway, endothelial injury, and thrombotic microangiopathy (TMA). Eculizumab is a humanized monoclonal antibody that inhibits the production of the terminal complement components C5a and the membrane attack complex (C5b-9) by binding to complement protein C5a. This blocks the proinflammatory and cytolytic effects of terminal complement activation. Eculizumab use has been reported in many case reports, and retrospective and prospective clinical trials in aHUS. There have been few serious side effects and no reports of tachphylaxis or drug resistance. The results are very encouraging and eculizumab is now recognized as the treatment of choice for aHUS.

Long-term outcomes of Shiga toxin hemolytic uremic syndrome

Shiga toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome (HUS) is an important cause of acute kidney injury (AKI). The outcomes of STEC HUS have improved, and the acute mortality rate in children is 1-4%. About 70% of patients recover completely from the acute episode and the remainder have varying degrees of sequelae. Only a few retrospective studies have reviewed these patients over long periods. Methodological flaws include a lack of strict definitions, changing modes of treatment, ascertainment bias and loss of subjects to follow-up. The kidneys bear the brunt of the long-term damage: proteinuria (15-30% of cases); hypertension (5-15%); chronic kidney disease (CKD; 9-18%); and end-stage kidney disease (ESKD; 3%). A smaller number have extra-renal sequelae: colonic strictures, cholelithiasis, diabetes mellitus or brain injury. Most renal sequelae are minor abnormalities, such as treatable hypertension and/or variable proteinuria. Most of the patients who progress to ESKD do not recover normal renal function after the acute episode. Length of anuria (more than 10 days) and prolonged dialysis are the most important risk factors for a poor acute and long-term renal outcome. After the acute episode all patients must be followed for at least 5 years, and severely affected patients should be followed indefinitely if there is proteinuria, hypertension or a reduced glomerular filtration rate (GFR).

End-stage kidney disease after pediatric nonrenal solid organ transplantation

OBJECTIVES

Adult solid organ transplant (SOT) recipients commonly develop advanced kidney disease; however, the burden of end-stage kidney disease (ESKD) in children after SOT is not well-described. The objectives of this study were to determine the incidence of ESKD after pediatric SOT and the relative risk by SOT type.

METHODS

Retrospective multicenter cohort study of children, ages ≤ 18 years, who received SOTs from 1990 through 2010 using Scientific Registry of Transplant Recipients data linked to the US Renal Data System. We performed a competing risks analysis to determine cumulative incidence of ESKD (chronic dialysis or kidney transplant), treating death as a competing risk, and fit a multivariable Cox regression model to assess hazard of ESKD by organ type.

RESULTS

The cohort included 16,604 pediatric SOT recipients (54% liver, 34% heart, 6% lung, 6% intestine, and 1% heart-lung). During a median follow-up of 6.2 years (interquartile range 2.2-12.1), 426 (3%) children developed ESKD. Compared with liver transplant recipients, in whom the incidence of ESKD was 2.1 cases per 1000 person-years, in adjusted analyses the highest risk of ESKD was among intestinal (hazard ratio [HR] 7.37, P < .001), followed by lung (HR 5.79, P < .001) and heart transplant recipients (HR 1.79, P < .001).

CONCLUSIONS

In a 20-year national cohort of pediatric SOT recipients, the risk of ESKD was highest among intestinal and lung transplant recipients. The burden of earlier stages of chronic kidney disease is probably much higher; modifiable risk factors should be targeted to prevent progressive kidney damage in this high-risk population.

Risk factors for end-stage kidney disease after pediatric liver transplantation

Adult liver transplant (LT) recipients commonly develop advanced kidney disease. However, burden of end-stage kidney disease (ESKD) after pediatric LT has not been well-described. We performed a retrospective cohort study of pediatric LTs in the United States from 1990 to 2010. Multivariable Cox regression models were fit to determine risk factors for ESKD and death. Eight thousand nine hundred seventy six children received LTs. During median follow-up of 7.8 years, 2005 (22%) subjects died (mortality rate 26.1 cases/1000 person-years); 167 (2%) developed ESKD (incidence rate 2.2 cases/1000 person-years). Risk factors for ESKD included older age at LT (highest risk age >15 vs. < 5 years, HR = 4.94, p < 0.001), hepatitis C (HR 2.79, p = 0.004), liver re-transplant (HR 2.67, p < 0.001), eGFR pre-LT < 60 versus ≥ 60 (HR 2.37, p < 0.001), hepatitis B (HR 2.25, p = 0.027), black race (HR 1.46, p = 0.046), and male sex (HR 1.44, p = 0.022). LT recipients with ESKD had increased risk of mortality (HR 2.37, p < 0.001). Among pediatric LT recipients, rate of ESKD was lower than among adults and far exceeded by rate of death, however follow-up time in this study may underestimate lifetime burden of ESKD. Although uncommon, ESKD was highly associated with mortality. Pediatric LT recipients should be routinely monitored for kidney disease, particularly those at highest risk of ESKD.

A time for reappraisal of "atypical" hemolytic uremic syndrome: should all patients be treated the same?

Atypical hemolytic uremic syndrome (HUS) refers to the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury in the absence of Shiga toxin-producing Escherichia coli exposure or Streptococcus pneumoniae infection. Currently, approximately 50 % of the atypical cases have demonstrable mutations in complement regulatory proteins. Historically, the diagnosis of atypical HUS portends a poor prognosis with a high rate of disease recurrence, progression to end-stage renal disease, and death. However, it is now evident that atypical HUS actually encompasses a heterogeneous group of disorders, and there are reports suggesting that some cases of atypical HUS have a favorable prognosis, similar to that of diarrhea-associated disease. We present three patients with the atypical HUS phenotype who had complete renal recovery and no disease recurrence. We believe it is important to distinguish those cases of atypical HUS associated with disorders of complement regulatory proteins from other idiopathic causes of nondiarrheal HUS given the implications for prognosis and treatment.

CONCLUSION

Given the heterogeneous nature and variable prognosis of atypical HUS, treatment should be carefully considered prior to the use of long-term plasma therapy and/or eculizumab.