Screening for CKD in children: a global controversy

Cost-Effectiveness of School Urinary Screening for Early Detection of IgA Nephropathy in Japan

Importance

The evidence for and against screening for chronic kidney disease in youths who are asymptomatic is inconsistent worldwide. Japan has been conducting urinary screening in students for 50 years, allowing for a full economic evaluation that includes the clinical benefits of early detection and intervention for chronic kidney disease.

Objectives

To evaluate the clinical effectiveness and cost-effectiveness of school urinary screening in Japan, with a focus on the benefits of the early detection and intervention for IgA nephropathy, and to explore key points in the model that are associated with the cost-effectiveness of the school urinary screening program.

Design, Setting, and Participants

This economic evaluation with a cost-effectiveness analysis used a computer-simulated Markov model from the health care payer's perspective among a hypothetical cohort of 1 000 000 youths aged 6 years in first grade in Japanese elementary schools, followed up through junior and high school. The time horizon was lifetime. Costs and clinical outcomes were discounted at a rate of 2% per year. Costs were calculated in Japanese yen and 2020 US dollars (¥107 = US $1).

Interventions

School urinary screening for IgA nephropathy was compared with no screening.

Main Outcomes and Measures

Outcomes were costs and quality-adjusted life-years (QALYs). Cost-effectiveness was determined by evaluating whether the incremental cost-effectiveness ratio (ICER) per QALY gained remained less than ¥7 500 000 (US $70 093).

Results

In the base case analysis, the ICER was ¥4 186 642 (US $39 127)/QALY, which was less than the threshold. There were 60.3 patients/1 000 000 patients in the no-screening strategy and 31.7 patients/1 000 000 patients in the screening strategy with an end-stage kidney disease. Cost-effectiveness improved as the number of screenings decreased (screening frequency <3 times: incremental cost, -¥75 [US $0.7]; incremental QALY, 0.00025; ICER, dominant), but the number of patients with end-stage kidney disease due to IgA nephropathy increased (40.9 patients/1 000 000 patients). Assuming the disutility due to false positives had a significant impact on the analysis; assuming a disutility of 0.01 or more, the population with no IgA nephropathy had an ICER greater than the threshold (¥8 304 093 [US $77 608]/QALY).

Conclusions and Relevance

This study found that Japanese school urinary screening was cost-effective, suggesting that it may be worthy of resource allocation. Key factors associated with cost-effectiveness were screening cost, the probability of incident detection outside of screening, and IgA nephropathy incidence, which may provide clues to decision-makers in other countries when evaluating the program in their own context.

Ethnicity and IgA nephropathy: worldwide differences in epidemiology, timing of diagnosis, clinical manifestations, management and prognosis

Immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis, is one of the major causes of end-stage renal disease. Significant variances in epidemiology, clinical manifestation, timing of diagnosis, management and renal prognosis of IgAN have been reported worldwide. The incidence of IgAN is the most frequent in Asia, followed by Europe, and lower in Africa. Moreover, Asian patients show more frequent acute lesions in renal histology and present poorer renal outcomes compared with Caucasians. The comorbidities also show the difference between Asians and Caucasians. Although the frequency of gross hematuria with upper respiratory tract infection is not different, comorbidities with gastrointestinal diseases are reported to be higher in Europe. Recently, genetic studies for variant ethnic patients revealed widely ranging genetic risks in each ethnicity. A genetic risk score is most elevated in Asians, intermediate in Europeans and lowest in Africans, consistent with the disease prevalence of IgAN globally. Ethnic variance might be highly affected by the difference in genetic background. However, it is also essential to mention that the different timing of diagnosis due to variant urinary screening systems and the indication for renal biopsy in different countries may also contribute to these variances. The management of IgAN also varies internationally. Currently, several novel therapies based on the pathogenesis of IgAN are being assessed and are expected to become available soon. Further understanding the ethnic variance of IgAN might help establish individualized care for this disease. Here, we review the issues of ethnic heterogeneities of IgAN.

Symptoms for early diagnosis of chronic kidney disease in children - a machine learning-based score

The objective of this study was to reveal the signs and symptoms for the classification of pediatric patients at risk of CKD using decision trees and extreme gradient boost models for predicting outcomes. A case-control study was carried out involving children with 376 chronic kidney disease (cases) and a control group of healthy children (n = 376). A family member responsible for the children answered a questionnaire with variables potentially associated with the disease. Decision tree and extreme gradient boost models were developed to test signs and symptoms for the classification of children. As a result, the decision tree model revealed 6 variables associated with CKD, whereas twelve variables that distinguish CKD from healthy children were found in the "XGBoost". The accuracy of the "XGBoost" model (ROC AUC = 0.939, 95%CI: 0.911 to 0.977) was the highest, while the decision tree model was a little lower (ROC AUC = 0.896, 95%CI: 0.850 to 0.942). The cross-validation of results showed that the accuracy of the evaluation database model was like that of the training.

CONCLUSION

In conclusion, a dozen symptoms that are easy to be clinically verified emerged as risk indicators for chronic kidney disease. This information can contribute to increasing awareness of the diagnosis, mainly in primary care settings. Therefore, healthcare professionals can select patients for more detailed investigation, which will reduce the chance of wasting time and improve early disease detection.

WHAT IS KNOWN

• Late diagnosis of chronic kidney disease in children is common, increasing morbidity. • Mass screening of the whole population is not cost-effective.

WHAT IS NEW

• With two machine-learning methods, this study revealed 12 symptoms to aid early CKD diagnosis. • These symptoms are easily obtainable and can be useful mainly in primary care settings.

Urine alpha 1-microglobulin-to-creatinine ratio and beta 2-microglobulin-to-creatinine ratio for detecting CAKUT with kidney dysfunction in children

BACKGROUND

The leading cause of advanced chronic kidney disease (CKD) in children is congenital anomalies of the kidney and urinary tract (CAKUT). However, the most appropriate parameters of biochemical urine analysis for detecting CAKUT with kidney dysfunction are not known.

METHODS

The present observational study analyzed data on children with CAKUT (stage 2-4 CKD) and the general pediatric population obtained from school urine screenings. The sensitivity and specificity of urine alpha 1-microglobulin-, beta 2-microglobulin-, protein-, and the albumin-to-creatinine ratios (AMCR, BMCR, PCR, ACR, respectively) in detecting CAKUT with kidney dysfunction were compared with those of the conventional urine dipstick, and the most appropriate of these four parameters were evaluated.

RESULTS

In total, 77 children with CAKUT and 1712 subjects in the general pediatric population fulfilled the eligibility criteria. Conventional dipstick urinalysis was insufficient due to its low sensitivity; even when the threshold of proteinuria was +/-, its sensitivity was only 29.7% for stage 2 and 44.1% for stage 3 CKD. Among the four parameters assessed, the AMCR and BMCR were adequate for detecting CAKUT in children with stage 3-4 CKD (the respective sensitivity and specificity of the AMCR for detecting CAKUT in stage 3 CKD was 79.4% and 97.5% while that of BMCR was 82.4% and 97.5%). These data were validated using national cohort data.

CONCLUSION

AMCR and BMCR are superior to dipstick urinalysis, PCR, and ACR in detecting CAKUT with kidney dysfunction, particularly stage 3 CKD. However, for AMCR, external validation is required. A higher resolution version of the Graphical abstract is available as Supplementary information.

Evaluation of Proteinuria and Hematuria in Ambulatory Setting

Proteinuria and/or hematuria are common findings in ambulatory settings. Proteinuria can be glomerular and/or tubular in origin and it may be transient, orthostatic, or persistent. Persistent proteinuria may be indicative of a serious kidney pathology. Hematuria, which denotes the presence of an increased number of red blood cells in the urine, can be gross or microscopic. Hematuria can originate from the glomeruli or other sites of the urinary tract. Asymptomatic microscopic hematuria or mild proteinuria in an otherwise healthy child is less likely to be of clinical significance. However, the presence of both requires further workup and careful monitoring.

Urinary Screening in Asymptomatic Indian Children: A Cross Sectional Epidemiological Study

BACKGROUND AND AIMS

Early detection and management of renal abnormalities in children can reduce the progression of paediatric chronic kidney disease. Currently, data on the prevalence of routine abnormal urinary parameters are scarce in Indian population. This study aims to identify the prevalence of asymptomatic kidney diseases in Indian school children and the population who may benefit from routine urinary screening tests for timely identification and intervention of asymptomatic renal diseases.

MATERIALS AND METHODS

A total of 1675 children from a North Indian, multiethnic population aged 5-19 years were screened for hematuria and proteinuria by dipstick test from a midstream, clean urine specimen. The children who tested positive had their urine tested further for microscopy. The incidences of proteinuria and hematuria were also separately checked in hypertensive children.

RESULTS

76 children had urinary abnormalities with the prevalence of isolated haematuria in 1.9%, isolated proteinuria in 0.35% and glycosuria in 0.06%. When these children were followed with urine microscopy, 44 were observed to have abnormal findings. Of these, 4.5% children had proteinuria, 34% had isolated hematuria, and 47.7% had isolated WBCs. The prevalence for proteinuria was 0.60% and the prevalence for hematuria was 2.99% (in upper decile of SBP) in hypertensive children, both of which were more than the prevalence in otherwise healthy children.

CONCLUSION

Urine screening is a non-invasive, inexpensive test for early detection of occult renal diseases. A large-scale study with follow-up of children with urinary abnormalities will further establish the benefit, if any, of a national paediatric urine screening programme.

Urinary biomarkers indicate pediatric renal injury among rural farming communities in Sri Lanka

Pediatric renal injury is an emerging health concern in communities affected by chronic kidney disease of uncertain etiology (CKDu). Early detection of susceptibilities through highly sensitive and specific biomarkers can lead to effective therapeutic and preventive interventions against renal diseases. Here, we aimed to investigate the utility of kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) in early detection of renal abnormalities in selected pediatric communities in Sri Lanka. The study areas were stratified as CKDu endemic, emerging, and non-endemic based on the prevalence of CKDu, and a total of 804 school students (10–18 years of age) participated in the study. The median (IQR) urinary KIM-1 levels of the participants were 0.193 (0.026–0.338), 0.082 (0.001–0.220) and 0.040 (0.003–0.242) ng/mgCr for CKDu endemic, emerging and non-endemic regions respectively. Participants from CKDu endemic regions reported elevated (p < 0.0001) urinary KIM-1 expression compared to those from the other regions. The median (IQR) NGAL levels in participants from CKDu endemic (2.969; 1.833–5.641), emerging (3.374; 1.766–6.103), and non-endemic (3.345; 1.742–5.128 ng/mgCr) regions showed no significant difference. Also, urinary albumin-creatinine ratio (UACR) showed no significant differences across gender or residency. The prevalence of albuminuria was 1–2% in the locations irrespective of CKDu burden. Albuminuric participants reported higher (p < 0.05) urinary KIM-1 levels in comparison to normoalbuminuric participants. Significantly elevated urinary KIM-1 expression in a pediatric population from CKDu affected regions, especially in the presence of albuminuria, may indicate low-grade early renal damage supporting the utility of KIM-1 as a quantifiable biomarker.

[Epidemiology of pediatric chronic kidney disease]

Major advances have been made in the management of children with chronic kidney disease over the past 30 years. However, existing epidemiology data are primarily from kidney replacement therapy registries, and information available at earlier stages of chronic kidney disease is limited. The incidence and prevalence of chronic kidney disease stages 2 to 5 remain poorly understood. However, rare population-based studies suggest that the prevalence of all-stage chronic kidney disease may be as high as 1% of the pediatric population. Congenital disorders including congenital abnormalities of the kidney and urinary tract and hereditary nephropathies account for one-half to two-thirds of pediatric chronic kidney disease cases in middle and high-income countries, whereas acquired nephropathies seem to predominate in low-income countries. The progression of chronic kidney disease is slower in children with congenital disorders than in those with acquired nephropathy, particularly glomerular disease, resulting in a lower proportion of congenital abnormalities of the kidney and urinary tract as a cause of end-stage kidney disease compared to less advanced stages of chronic kidney disease. The incidence of kidney replacement therapy in the pediatric population ranged by country from 1 to 14 per million children of the same age in 2018 (approximately 8 per million children in France) in patients younger than 20 years. The prevalence of kidney replacement therapy in children under 20 years of age in 2018 ranged from 15-30 per million children in some Eastern European and Latin American countries to 100 per million children in Finland and the United States (56 per million children in France). Most children with end-stage kidney disease initiate kidney replacement therapy with dialysis (more frequently hemodialysis than peritoneal dialysis). In about 20% of cases, the initial kidney replacement therapy modality is a pre-emptive kidney transplantation. In high-income countries, 60-80% of prevalent children with end-stage kidney disease live with a functioning transplant (75% in France). While the survival of children with chronic kidney disease has continuously improved over time, mortality remains about 30 times higher than in the general pediatric population.

Impact of a screen, triage and treat program for identifying chronic disease risk in Indigenous children

BACKGROUND

The First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis project was a point-of-care screening program in rural and remote First Nations communities in Manitoba that aimed to identify and treat hypertension, diabetes and chronic kidney disease. The program identified chronic disease in 20% of children screened. We aimed to characterize clinical screening practices before and after intervention in children aged 10-17 years old and compare outcomes with those who did not receive the intervention.

METHODS

This observational, prospective cohort study started with community engagement and followed the principles of ownership, control, access and possession (OCAP). We linked participant data to administrative data at the Manitoba Centre for Health Policy to assess rates of primary care and nephrology visits, disease-modifying medication prescriptions and laboratory testing (i.e., glycosylated hemoglobin [HbA_1c], estimated glomerural filtration rate [eGFR] and urine albumin- or protein-to-creatinine ratio). We analyzed the differences in proportions in the 18 months before and after the intervention. We also conducted a 1:2 propensity score matching analysis to compare outcomes of children who were screened with those who were not.

RESULTS

We included 324 of 353 children from the screening program (43.8% male; median age 12.3 yr) in this study. After the intervention, laboratory testing increased by 5.8% (95% confidence interval [CI] 1.1% to 10.1%) for HbA_1c, by 9.9% (95% CI 4.2% to 15.5%) for eGFR and by 6.2% (95% CI 2.3% to 10.0%) for the urine albumin- or protein-to-creatinine ratio. We observed significant improvements in laboratory testing in screened patients in the group who were part of the program, compared with matched controls.

INTERPRETATION

Chronic disease surveillance and care increased significantly in children after the implementation of a point-of-care screening program in rural and remote First Nation communities. Interventions such as active surveillance programs have the potential to improve the chronic disease care being provided to First Nations children.

Childhood risk factors for adulthood chronic kidney disease

Chronic kidney disease (CKD) is a major public health challenge, affecting as much as 8 to 18% of the world population. Identifying childhood risk factors for future CKD may help clinicians make early diagnoses and initiation of preventive interventions for CKD and its attendant comorbidities as well as monitoring for complications. The purpose of this review is to describe childhood risk factors that may predict development of overt kidney disease later in life. Currently, there are multiple childhood risk factors associated with future onset and progression of CKD. These risk factors can be grouped into five categories: genetic factors (e.g., monogenic or risk alleles), perinatal factors (e.g., low birth weight and prematurity), childhood kidney diseases (e.g., congenital anomalies, glomerular diseases, and renal cystic ciliopathies), childhood onset of chronic conditions (e.g., cancer, diabetes, hypertension, dyslipidemia, and obesity), and different lifestyle factors (e.g., physical activity, diet, and factors related to socioeconomic status). The available published information suggests that the lifelong risk for CKD can be attributed to multiple factors that appear already during childhood. However, results are conflicting on the effects of childhood physical activity, diet, and dyslipidemia on future renal function. On the other hand, there is consistent evidence to support follow-up of high-risk groups.

Alport Syndrome: Achieving Early Diagnosis and Treatment

Alport syndrome is a genetically and phenotypically heterogeneous disorder of glomerular, cochlear, and ocular basement membranes resulting from mutations in the collagen IV genes COL4A3, COL4A4, and COL4A5. Alport syndrome can be transmitted as an X-linked, autosomal recessive, or autosomal dominant disorder. Individuals with Alport syndrome have a significant lifetime risk for kidney failure, as well as sensorineural deafness and ocular abnormalities. The availability of effective intervention for Alport syndrome-related kidney disease makes early diagnosis crucial, but this can be impeded by the genotypic and phenotypic complexity of the disorder. This review presents an approach to enhancing early diagnosis and achieving optimal outcomes.

Uptake of further investigations following universal urinary screening among elementary and junior high school students in Shiga Prefecture, Japan: A retrospective cohort study

AIM

This study aimed to investigate the current progression status from screening phase to further investigation phase in the Japanese school urine mass screening (SUS) project.

METHODS

This retrospective cohort study on the SUS project across the Shiga Prefecture during 2012 to 2017 analysed data from school life instruction sheets, which are principal documents in the SUS project, regarding urinalysis, attendance at follow-up and diagnoses.

RESULTS

Between the years 2012 to 2017, a median of 107 out of 83 749 elementary school students (aged 6-11 years) and 215 out of 42 870 junior high students (aged 12-14 years) had urine abnormalities identified for the first time in the SUS project. Among those with urine abnormalities, a mean of 4.2% of elementary school and 1.8% of junior high school students, respectively, were diagnosed with suspected glomerulonephritis for the first time. Overall, 5.9% (95% confidence interval [CI] 4.1, 7.7) and 23.6% (95% CI 21.3, 25.9) of proteinuria-positive elementary and junior high school students, respectively, did not undergo further investigations. The probability of a student undergoing further investigations was not affected by the local availability of medical care benefits.

CONCLUSION

In the current SUS project, screening frequently does not lead to further investigation, especially among junior high school students. To maintain the integrity of the SUS project and to prevent the progression of renal disease in young students, efforts including elucidation of barriers to further investigations should be made to reduce the proportions of students not undergoing further investigations for abnormal urinalysis findings.

Screening for diabetes in asymptomatic children: A simple and efficient method

BACKGROUND/PURPOSE

Type 2 diabetes has become an important cause of diabetes in children. Since most children with type 2 diabetes are asymptomatic, a screening method is needed. However, physicians are required in the screening methods recommended by professional associations. We aimed to develop a simple and efficient screening method for children with diabetes.

METHODS

A nationwide survey was conducted, which included 2,270,496 seventh-grade students. Students with two abnormal results in sequential urinalyses were given a fasting blood test. Three screening methods were developed.

RESULTS

Among the screening methods, method C is simple, and can be performed by parents, teachers, or school nurses. It suggests children with two abnormal results in sequential urinalyses and who are overweight or have a family history of diabetes receive blood tests. As a result, 0.10% of boys and 0.16% of girls were recommended to receive blood tests, and 7.0% of boys and 6.7% of girls receiving blood tests were diagnosed diabetes. On average, 15,002 boys and 9056 girls had to be screened to find one child with diabetes. The cost per 1000 children by method C was 2466.84 US dollars.

CONCLUSION

Urinalysis screening followed by evaluation of risk factors is a simple and efficient way to identify children with diabetes in schools.

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

Objective

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

Study design

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

Results

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

Conclusions

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

Urinary Screening for Early Detection of Kidney Diseases

OBJECTIVE

Urinary screening is a simple inexpensive tool to evaluate kidney functions. The authors carried out urinary screening of school children for early detection of kidney diseases.

METHODS

Children in the age group 5-15 y were screened for urinalysis. They were divided in 2 groups; group-1 included 5-10 y and group-2 included >10-15 y old children.

RESULTS

Urine samples of 3340(78%) out of 4283 enrolled children were tested. Abnormal samples were found in 5.75%; with proteinuria in 4.59%, pyuria in 3.29% and hematuria in 4.31%. Males constituted 47.71% in group-1 and 54.64% in group-2. Low body mass index was found in 94.1% group-1 and 78.99% group-2 children. Mild proteinuria was found in 1.2% group-1 and 2.56% group-2 children. Severe proteinuria was more in group-2 (0.77% vs. 0.06%) with female preponderance. Glucosuria was found in 1 boy of group-2. Urobilinogen was more in group-2 (0.65% vs. 0.24%) with male preponderance. Nitrituria was found in 9 girls. Pyuria (2.02% vs. 1.27%) and hematuria were more in group-2 (3.04% vs. 1.87%) with female preponderance. Combined proteinuria and hematuria (0.42% vs. 0.24%) as well bacteruria and fungaluria were more in group-2 (4.11% vs. 1.39%). Six of 192 children with abnormal urinary findings were treated; 1 for urinary calculus and 5 for urinary tract infection.

CONCLUSIONS

Abnormal urinary findings were more common in children >10 y of age. Thus urinary screening program of children can become useful for early detection of kidney diseases and contribute towards building up of a healthy nation.

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

RATIONALE & OBJECTIVE

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

STUDY DESIGN

Serial cross-sectional national surveys.

SETTING & PARTICIPANTS

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

PREDICTORS

Demographic and clinical determinants of kidney markers.

OUTCOME

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

ANALYTICAL APPROACH

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Early renal damage among children living in the region of highest burden of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka

Background

Chronic kidney disease of unknown origin (CKDu) in Sri Lanka is grouped with several other epidemics of similar nature across the world as Chronic Interstitial Nephritis in Agricultural Communities (CINAC). In CKDu endemic countries, the focus has mainly been on adults. We hypothesized that studying distribution and factors associated with elevated urine albumin to creatinine ratio (UACR), an early marker of kidney injury, among children living in a CKDu endemic area may provide important clues about the onset and progression of the disease.

Methods

This cross sectional study was performed in rural primary schools in North Central Province of Sri Lnaka, a CKDu high endemic region. Total of 2880 students aging 5 to 11 years from 67 schools were enrolled for urinalysis in a random spot urine sample. Bedside Schwartz formula was used to measure estimated glomerular filtration rate (eGFR) on all children with UACR > 30 mg/g in Polonnaruwa district and a group of age matched controls. A standard multiple linear regression using log transformed UACR as the dependent variable was performed. Mean eGFR were compared between UACR elevated group and controls using independent sample t test.

Results

Median UACR was 10.3 mg/g. Sex, ethnicity, history of having a chronic disease and age uniquely contributed to the multiple regression model which only explained 2.8% of the variance in the log of the UACR (p < 0.001). Only 15 (0.5%) had UACR> 300 mg/g while 8.2% (n = 236) had UACR between 30 to 300 mg/g and 89.8% (n = 203) of them did not have a chronic disease (Chi square 2.21, p = 0.091). Mean eGFR was significantly lower in the group with elevated UACR (88.9 mg/dl/1.73 m2, 95% CI for mean 86.4- 91.3) compared to group with normal UACR (93.7 mg/dl/1.73 m2,95% CI 91.1- 96.3) (t 2.7, p 0.007). Three out of the four students with eGFR less than 60 mg/dl/1.73 m2 had moderately elevated UACR.

Conclusion

This study provides evidence to suggest that children in CKDu endemic regions are having an early renal damage. This observation needs to be investigated further in order to understand the worldwide epidemic of CKDu.

Screening for kidney disease in Indigenous Canadian children: The FINISHED screen, triage and treat program

Background

Indigenous populations are disproportionately affected by kidney failure at younger ages than other ethnic groups in Canada. As symptoms do not occur until disease is advanced, early kidney disease risk is often unrecognized.

Objectives

We sought to evaluate the yield of community-based screening for early risk factors for kidney disease in youth from rural Indigenous communities in Canada.

Methods

The FINISHED project screened 11 rural First Nations communities in Manitoba, Canada after community and school engagement. The results for the 10- to 17-year olds are reported here. Body mass index (BMI), blood pressure, estimated glomerular filtration rate (eGFR), hemoglobin A1c's (HbA1c) and urine albumin-to-creatinine ratios (ACR) were assessed. All children were triaged and referred to either primary or tertiary care, depending on risk.

Results

A total of 353 were screened (estimated 22.4% of population). The median age was 12 years (IQR 10 to 13), 55% were female and 55% were overweight or obese. Overall, 21.8% of children had at least one abnormality. Hypertension was identified in 5.4% and 11.9% had prehypertension. None of the children had an eGFR < 60 ml/min/1.73 m² however 10.5% had an ACR > 3 mg/mmol and 6.2% had an eGFR < 90 ml/min/1.73 m² suggestive of early kidney disease. Diabetes was identified in 1.4%, and 1.4% had HbA1c's between 6.1% and 6.49%.

Conclusions

Risk factors for chronic kidney disease are highly prevalent in rural Indigenous children. More research is required to confirm the persistence of these findings, and to evaluate the efficacy of screening children to prevent or delay progression to kidney failure.

Prevalence of Albuminuria in Children Living in a Rural Agricultural and Fishing Subsistence Community in Lake Chapala, Mexico

The occurrence of Chronic Kidney Disease (CKD) of unknown etiology in autochthonous child populations residing along the Lake Chapala lakeshore is endemic (Jalisco, México). The objective of this study was to determine the prevalence of albuminuria in the pediatric population and to measure the glomerular filtration rate in children with two positive albuminuria tests. Urinary albumin was measured in 394 children. Subjects with two or more positive albuminuria test donated blood samples for the determination of serum biomarkers. From a rural community with 565 children under the age of 17 years, 394 (69.7%) participated with first morning urine samples. A total of 180 children were positive (with two or more positive albuminuria tests). The prevalence of albuminuria among the children participating in the study was 45.7%. Of the 180 children with persistent albuminuria, 160 (88.9%) were tested for serum creatinine, urea, and cystatin C. The 68.1% of the children studied, were found in stages 3a and 3b of the Kidney Disease Improving Global Outcomes (KDIGO) classification (mean glomerular filtration rate (GFR) 51.9 and 38.4 mL/min/1.73 m² respectively). The lowest frequencies were for classifications 1 and 4. None of the subjects was classified as grade 5. The prevalence of albuminuria in children from this rural community is 3-5 times higher than reported in international literature. Regarding GFR, more than 50% of children studied are under 60 mL/min/1.73 m². It is a priority to find the causes of albuminuria and CKD in this Mexican region.

Non-Traditional Risk Factors of Albuminuria in the Pediatric Population: A Scoping Review

The presence of albumin in urine has been used for more than four decades as a marker of renal and cardiovascular damage. Most of the information on this marker is related to adults. The prevalence of albuminuria in the pediatric population has been reported as being 2.2–12.8% in some countries. Most research in this field is related to albuminuria and diseases, such as diabetes and hypertension. Using the methodology described by Arksey and O’Malley in 2005, a scoping review was carried out to show that the presence of albumin in urine in the pediatric population might be associated with environmental, demographic, congenital, infectious, and non-infectious factors. The information collected is supported by 74 references present in PubMed. The results reveal the multiple causes associated with albuminuria in the pediatric population. This information can be very useful for clinical practice by adding knowledge about albuminuria behavior in children.

A Cross-sectional Prospective Study of Asymptomatic Urinary Abnormalities, Blood Pressure, and Body Mass Index in Healthy School Children

Introduction

Screening school children for urinary abnormalities is an inexpensive task but is not commonly undertaken in India. Although debated in western countries, its utility in early diagnosis of kidney disorders has been proved by studies from Asia. We examined the prevalence of asymptomatic urinary abnormalities (AUA), obesity, and hypertension in school children and analyzed data to identify potential risk factors among those detected with such abnormalities.

Methods

Children and adolescents 8 to 18 years of age of either gender, attending 14 public schools in West Bengal, were screened prospectively from July 2013 to July 2016 for detecting asymptomatic urinary abnormalities by a spot urine test using a dipstick. Sociodemographic profile, medical examination (weight, height, and blood pressure), and questionnaire-based data were recorded.

Results

A total of 11,000 children were screened. Of these, data from 9306 children were available for AUA, obesity, and hypertension. The prevalence rate was 7.44% (95% confidence interval [CI] = 6.91%−7.97%) for at least 1 AUA. Isolated hematuria was present in 5.2% (95% CI 4.75%−5.65%), whereas isolated proteinuria was present in 1.9% (95% CI = 1.62%−2.18%). The prevalence of prehypertension was 13.43% (95% CI = 12.74%−14.12%) and that of hypertension and abnormal body mass index was 4.05% (95% CI = 6.43%−7.47%) and 38.67 (95% CI = 37.68%−39.66%) respectively.

Discussion

The prevalence rates of AUA were comparable with those in some Asian countries but higher than in most developed countries. Of children and adolescents 8 to 18 years of age, those 13 to 18 years had significantly more high risk factors such as AUA, hypertension, and obesity.

Pottels Equation for Estimation of Glomerular Filtration Rate

The retrospective study was carried out to examine performance of Pottels height- independent equation compared to Schwartzs height-dependent equation to estimate glomerular filtration rate in 115 children in Indian setting. The Pottels equation performed well compared to updated Schwartz equation (R2=0.94, mean bias 0.25, 95% LOA=20.4, -19.9). The precision was better at lower range of estimated GFR.

Signs and symptoms of developmental abnormalities of the genitourinary tract

OBJECTIVE

The abnormalities of the genitourinary tract development are the leading cause of chronic kidney disease (CKD) in children. The diagnosis of this disease in Brazil is late and incomplete, which results in increased morbidity and mortality in this age group. Early diagnosis of this condition is the prerogative of generalist pediatricians, and the aim of this study was to review the clinical signs and symptoms associated with developmental abnormalities of the genitourinary tract.

DATA SOURCES

Based on the description of a symbolic clinical case, the authors conducted a non-systematic review of medical literature.

DATA SYNTHESIS

The results suggest that the following data should be used as a warning for early diagnosis of affected children: (a) combined urinary tract abnormalities (chromosomal abnormalities; sequence of malformations [VACTERLand Prune-Belly]; and musculoskeletal, digestive tract, heart, and nervous system malformations); (b) previous history (congenital anomalies of the kidney and urinary tract [CAKUT] in the family, low birth weight, and oligoamnios); (c) clinical signs (polyuria/nocturia, urinary tract infection, systemic arterial hypertension, failure to thrive, weak urinary stream, difficulty to start urination, distended bladder, non-monosymptomatic enuresis, urinary/urge incontinence, and bowel and bladder dysfunction); and (d) pre- and postnatal ultrasonographic alterations (increased anteroposterior diameter of the renal pelvis, mainly in the third trimester of pregnancy; single kidney; hydronephrosis associated with other abnormalities; and hydronephrosis with parenchymal involvement in the post-neonatal assessment).

CONCLUSION

The suggestions shown here can help the pediatrician to establish clinical hypotheses for the early diagnosis of developmental abnormalities of the genitourinary tract without resorting to expensive and invasive procedures.

Urinary screening and urinary abnormalities in 3-year-old children in Japan

In Japan, urinary screening for preschool children has been obligatory since 1961. The system was reconsidered and has been under review since 2012, because many problems in the system had been identified, and its usefulness was uncertain. In the process, the following were analyzed: (i) frequency of urinary abnormalities identified on screening; (ii) diseases identified from urinary abnormalities; (iii) clinical course of children found to have urinary abnormalities; and (iv) screening for asymptomatic urinary tract infection (UTI) as a way of screening for congenital anomalies of the kidney and urinary tract. A computerized literature search was conducted, and study reports issued by the Ministry of Health, Labour and Welfare study group, and data of Akita City and Chiba City were reviewed. The prevalence of abnormal results at the first urinalysis was high, but at the second urinalysis the prevalence decreased in the range 1/6-1/20. The prevalence of tentative diagnosis at the third urinalysis was similar to the school urinary screening results. Serious illness was not found in children who had hematuria alone. In contrast, diseases requiring immediate attention were found in children with proteinuria, although the prevalence of proteinuria was not high. The dipstick method for leukocyturia was inefficient. The importance of two consecutive urinalyses before detailed examination, the lack of usefulness of screening for hematuria in 3-year-old children, and the importance of proteinuria were confirmed. Screening for asymptomatic UTI using urinary leukocytes was very inefficient.

Screening with urinary dipsticks for reducing morbidity and mortality

BACKGROUND

Urinary dipsticks are sometimes used for screening asymptomatic people, and for case-finding among inpatients or outpatients who do not have genitourinary symptoms. Abnormalities identified on screening sometimes lead to additional investigations, which may identify serious disease, such as bladder cancer and chronic kidney disease (CKD). Urinary dipstick screening could improve prognoses due to earlier detection, but could also lead to unnecessary and potentially invasive follow-up testing and unnecessary treatment.

OBJECTIVES

We aimed to quantify the benefits and harms of screening with urinary dipsticks in general populations and patients in hospitals.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 8 September 2014 through contact with the Trials Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials and other study types that compared urinary dipstick screening with no dipstick screening were eligible for inclusion. We searched for studies that investigated the use of urinary dipsticks for detecting haemoglobin, protein, albumin, albumin-creatinine ratio, leukocytes, nitrite, or glucose, alone or in any combination, and in any setting. We planned to exclude studies conducted in patients with urinary disorders.

DATA COLLECTION AND ANALYSIS

It was planned that two authors would independently extract data from included studies and assess risk of bias using the Cochrane risk of bias tool. However, no studies met our inclusion criteria.

MAIN RESULTS

Literature searches to 8 September 2014 yielded 4298 records, of which 4249 were excluded following title and abstract assessment. There were 49 records (44 studies) eligible for full text assessment; of these 18 studies were not RCTs and 26 studies compared interventions or controls that were not relevant to this review. Thus, no studies were eligible for inclusion.

AUTHORS' CONCLUSIONS

We found no evidence to assess the benefits and harms of screening with urinary dipsticks, which remain unknown.

Height-independent estimation of glomerular filtration rate in children: an alternative to the Schwartz equation

OBJECTIVE

To compare the diagnostic performance of 2 height-independent equations used to calculate estimated glomerular filtration rate (eGFR), those of Pottel (eGFR-Pottel) and the British Columbia Children's Hospital (BCCH) (eGFR-BCCH), with the commonly used Schwartz equation (eGFR-Schwartz).

STUDY DESIGN

We externally validated eGFR-Pottel and eGFR-BCCH in a well-characterized pediatric patient population (n = 152) and compared their diagnostic performance with that of eGFR-Schwartz using Bland-Altman analysis. All patients underwent glomerular filtration rate measurement using the gold standard single-injection inulin clearance method (GFR-inulin).

RESULTS

Median GFR-inulin was 92.0 mL/min/1.73 m² (IQR, 76.1-107.4 mL/min/1.73 m²). Compared with GFR-inulin, the mean bias for eGFR-Schwartz was -10.1 mL/min/1.73 m(2) (95% limits of agreement [LOA], -77.5 to 57.2 mL/min/1.73 m(2)), compared with -12.3 mL/min/1.73 m² (95% LOA, -72.6 to 47.9 mL/min/1.73 m(2)) for eGFR-Pottel and -22.1 mL/min/1.73 m² (95% LOA, -105.0 to 60.8 mL/min/1.73 m(2)) for eGFR-BCCH. eGFR-Pottel showed comparable accuracy to eGFR-Schwartz, with 77% and 76% of estimates within 30% of GFR-inulin, respectively. eGFR-BCCH was less accurate than eGFR-Schwartz (66% of estimates within 30% of GFR-inulin; P < .01).

CONCLUSION

The performance of eGFR-Pottel is superior to that of eGFR-BCCH and comparable with that of eGFR-Schwartz. eGFR-Pottel is a valid alternative to eGFR-Schwartz in children and could be reported by the laboratory if height data are not available.

Epidemiological urinalysis of children from kindergartens of Can Gio, Ho Chi Minh City - Vietnam

Background

Recent studies on Vietnamese children have shown that kidney diseases are not detected early enough to prevent chronic renal failure. The dipstick test is a simple and useful tool for detecting urinary abnormalities, especially in isolated or remote areas of Vietnam, where children have limited access to health care.

Methods

This cross-sectional study was conducted in 2011 at seven kindergartens in Can Gio district, Ho Chi Minh City, Vietnam. Two thousand and twelve children, aged 3 to 5, were enrolled. Morning mid-stream urine samples were examined by dipstick. Children with abnormal findings were re-examined with a second dipstick and underwent further investigations.

Results

Urinalysis was available for 1,032 boys and 980 girls. Mean age was 4.4 ± 0.8 years. Urinary abnormalities were detected in 108 (5.5%) of the subjects. Among them, nitrituria and leucocyturia accounted for more than 50%. Positive fractions of proteinuria, hematuria, nitrituria, leucocyturia, and combined nitrituria and leucocyturia after two dipsticks were 0.1%, 0.1%, 2%, 1% and 0.3%, respectively. Abnormal findings were more common in girls than boys (p < 0.001), and higher in communes with very low (< 50 persons/km²) population density (14.3% vs 4.1%, p < 0.001). A renal ultrasound detected four cases of hydronephrosis and one case of duplication of ureter.

Conclusions

The prevalence of urinary abnormalities in asymptomatic children in South Vietnam demonstrates the need for hygiene education among parents. Training for dipstick usage for all medical staff at health stations, especially in remote areas and in places with very low population density, is also clearly necessary. Routine urinalysis can be set up if a close control is conducted at locations.

Chronic renal disease in children aged 5-18 years: a population-based survey in Turkey, the CREDIT-C study

BACKGROUND

Data on the epidemiology of chronic kidney disease (CKD), which is a serious health problem and refers to a condition related to irreversible kidney damage that further progress to end-stage renal disease in children, are insufficient and data that are available were based on hospital records. The aim of this nationwide, population-based field study was to determine the prevalence of CKD in children in Turkey and to evaluate the association between CKD and possible risk factors such as obesity and hypertension.

METHODS

The study was the paediatric stratum (3622 children aged 5-18 years) of the previously published population-based survey of Chronic REnal Disease In Turkey (CREDIT study). Medical data were collected through home visits and interviews between November 2007 and July 2008; height, weight and blood pressure were also measured. Serum creatinine, total cholesterol, uric acid and complete blood count were determined from 12-h fasting blood samples, and spot urine tests were performed for subjects who gave consent to laboratory evaluation.

RESULTS

Following adjustment according to gender, residence, age groups and geographical regions, the prevalence of children with estimated glomerular filtration rate (eGFR) <75 mL/min/1.73 m(2) was 0.94 [95% confidence interval (CI): 0.63-1.35], and the prevalence of children with CKD Stages 3-5 [National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (K/DOQI)] was 2600 (95% CI 1100-5100) per million age related population. The mean eGFR was found to increase with age; the ratios of children with eGFR <90 and <75 mL/min/1.73 m(2) were higher in younger age groups. The frequencies of overweight and obese children were 9.3 and 8.9%, respectively, and the mean eGFR was lower in patients with higher body mass index. The prevalence of hypertension and hypercholesterolaemia was 6.1 and 5.8%, respectively; the mean eGFR was lower in children with hypercholesterolaemia.

CONCLUSIONS

This is the first population-based CKD study performed in children aged 5-18 years. The prevalence of CKD in our study was 25-100 times greater than that found in previous hospital-based studies. Our data suggest that approaches focusing on patients in tertiary centres are likely to lead to patients being missed at early stages of CKD and that a vast majority of these children will never develop symptomatic CKD during childhood.

Urinalysis interpretation for pediatricians

CME EDUCATIONAL OBJECTIVES: 1.Cost-effectively evaluate microscopic hematuria and proteinuria.2.Recognize important conditions associated with isolated microscopic hematuria.3.Review important conditions associated with asymptomatic proteinuria.

Chronic kidney disease and automatic reporting of estimated glomerular filtration rate: new developments and revised recommendations

The publication of the Australasian Creatinine Consensus Working Group's position statements in 2005 and 2007 resulted in automatic reporting of estimated glomerular filtration rate (eGFR) with requests for serum creatinine concentration in adults, facilitated the unification of units of measurement for creatinine and eGFR, and promoted the standardisation of assays. New advancements and continuing debate led the Australasian Creatinine Consensus Working Group to reconvene in 2010. The working group recommends that the method of calculating eGFR should be changed to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, and that all laboratories should report eGFR values as a precise figure to at least 90 mL/min/1.73 m(2). Age-related decision points for eGFR in adults are not recommended, as although an eGFR < 60 mL/min/1.73 m(2) is very common in older people, it is nevertheless predictive of significantly increased risks of adverse clinical outcomes, and should not be considered a normal part of ageing.If using eGFR for drug dosing, body size should be considered, in addition to referring to the approved product information. For drugs with a narrow therapeutic index, therapeutic drug monitoring or a valid marker of drug effect should be used to individualise dosing. The CKD-EPI formula has been validated as a tool to estimate GFR in some populations of non-European ancestry living in Western countries. Pending publication of validation studies, the working group also recommends that Australasian laboratories continue to automatically report eGFR in Aboriginal and Torres Strait Islander peoples. The working group concluded that routine calculation of eGFR is not recommended in children and youth, or in pregnant women. Serum creatinine concentration (preferably using an enzymatic assay for paediatric patients) should remain as the standard test for kidney function in these populations.

Dipstick urine analysis screening among asymptomatic school children

Background:

Mass urinary screening is a useful tool to identify children with asymptomatic progressive renal diseases. A dipstick urinalysis screening was conducted to detect such prevalence and to set up a more effective screening program for children.

Patients and Methods:

A cross sectional study was carried out in seven nurseries and primary schools in different regions of Lebanon (Beirut, North Lebanon, and Valley of Bekaa) between February 2010 and March 2010. Eight hundred seventy asymptomatic children were enrolled in this study. First morning mid steam urine samples were obtained from students and were tested by dipstick method. Children with abnormal findings were re-tested after fifteen days.

Results:

Twenty five (2.9%) children had urinary abnormalities at the first screening; Eighteen (72%) of them still had abnormal results at the second screening. Among all the students, hematuria was the most common abnormality found with a prevalence of 1.5%, followed by nitrituria (0.45%), combined hematuria and nitrituria (0.45%) and proteinuria (0.1%). Urinary abnormalities were more common in females than in males. With respect to age, most positive results were detected at 6 years of age. Hematuria and proteinuria were mainly present in the North of Lebanon.

Conclusion:

Asymptomatic urinary abnormalities might be detected by urine screening program at school age. Further work-up should be offered to define the exact etiology of any abnormal finding and to determine whether early detection of renal disorders in childhood will lead to effective interventions and reduction in the number of individuals who develop end-stage renal disease.

A simple height-independent equation for estimating glomerular filtration rate in children

BACKGROUND

The chronic kidney disease (CKD) classification system for children is similar to the CKD classification system for adults, using estimated glomerular filtration rate (eGFR) combined with fixed cut-off values of 60, 30, and 15 ml/min/1.73 m(2) for CKD stages III, IV, and V, respectively. To estimate GFR in children, eGFR-equations are used that require serum creatinine (Scr), but also height information, which is normally not available in clinical laboratory databases.

METHODS

This retrospective study is based on data from two different databases, one that has previously been used to develop the Flanders Metadata equation for children and one database including 353 children who underwent (51)Cr-EDTA GFR, serum creatinine, height, and weight measurements.

RESULTS

A height-independent eGFR equation based on the concept of a population-normalized Scr, presented before for adults, is extended to children: eGFR = 107.3/(Scr/Q), with Q the median Scr for healthy children of a particular age. This equation is validated against direct measurements of GFR, and against the updated Schwartz and Flanders Metadata equation.

CONCLUSIONS

The new simple height-independent equation performs very well and should make (mass) screening of kidney function in children easier.

Epidemiology of chronic kidney disease in children

In the past 30 years there have been major improvements in the care of children with chronic kidney disease (CKD). However, most of the available epidemiological data stem from end-stage renal disease (ESRD) registries and information on the earlier stages of pediatric CKD is still limited. The median reported incidence of renal replacement therapy (RRT) in children aged 0-19 years across the world in 2008 was 9 (range: 4-18) [corrected] per million of the age-related population). [corrected] The prevalence of RRT in 2008 ranged from 18 to 100 per million of the age-related population. Congenital disorders, including congenital anomalies of the kidney and urinary tract (CAKUT) and hereditary nephropathies, are responsible for about two thirds of all cases of CKD in developed countries, while acquired causes predominate in developing countries. Children with congenital disorders experience a slower progression of CKD than those with glomerulonephritis, resulting in a lower proportion of CAKUT in the ESRD population compared with less advanced stages of CKD. Most children with ESRD start on dialysis and then receive a transplant. While the survival rate of children with ERSD has improved, it remains about 30 times lower than that of healthy peers. Children now mainly die of cardiovascular causes and infection rather than from renal failure.

Clinical practice: proteinuria

Proteinuria detection in children is a challenge. Five percent to 15% and 0.4-1% of school children present either transient (benign) or persistent increased amount of protein in urine, respectively. Persistent proteinuria constitutes not only a sign of overt kidney disease but may also be the first indicator of silent renal damage. Proteinuria is a marker for hyperfiltration in individuals with reduced nephron mass and one of the most important independent risk factor for renal disease progression as well. It constitutes the single most important risk factor for future loss of kidney function, preceding glomerular filtration rate reduction. Further, proteinuria itself is diagnostic of cardiovascular disease with prognostic value and target organ involvement in high-risk populations such as diabetic, obese, hypertensive children, or those with known reduced renal mass or previous renal injury. Current strategies to prevent CKD progression, a concept known as renoprotection, are focused on reducing urinary protein excretion among other factors. Reversibility of organ damage in early stages is possible; therefore, pediatricians should screen children for proteinuria or microalbuminuria, mainly in high-risk groups.

Ultrasound of urinary system and urinary screening in 14 256 asymptomatic children in China

AIM

The aim of this study is to assess the characteristics of urinary system diseases and the role of the ultrasound screening and urinalysis screening for chronic kidney disease (CKD) in asymptomatic children in China.

METHODS

Between September 2008 and November 2008, 14 256 children excluding those with obvious symptoms and signs were enrolled in our study. All the subjects accepted ultrasound and urinary screening. A case-control study was performed to evaluate the relative risk of having stones in those children exposed to melamine formula.

RESULTS

Of the enrolled children, 6.10% (869 of 14 256) showed abnormalities, of which 409 (2.87%) were established by ultrasound, 572 (4.01%) by urinalysis and 112 (0.79%) by both ultrasound screening and urinalysis. The abnormalities included congenital anomalies of kidney and urinary tract, urinary stones and/or hydronephrosis, leucocyturia and haematuria and/or proteinuria. Children exposed to melamine formula were 5.17 times as likely to have kidney stones as children exposed to no-melamine formula (95% confidence interval, 3.28-8.14; P < 0.001); the probability of kidney stones in melamine-fed infants were 6.28 times as likely as those no melamine-fed (95% confidence interval, 3.71-10.65; P < 0.001).

CONCLUSION

Ultrasonography and urinalysis could complement each other and play important roles in the early diagnosis of anomalies of the urinary system, but urinalysis is a more cost-effective screening tool for CKD in children in China. Exposure to melamine-contaminated formula associated with urinary stones, especially in infants, was significantly higher than the control group.