Extending the cystatin C based EKFC-equation to children - validation results from Europe.

BACKGROUND: A new cystatin C based European Kidney Function Consortium (EKFCCysC) equation was recently developed for adults, using the same mathematical form as the previously published full age spectrum creatinine based EKFC-equation (EKFCCrea). In the present study the cystatin C based EKFC-equation is extended to children, by defining the appropriate cystatin C rescaling factor QCysC. METHODS: Rescaling factor QCysC for cystatin C was defined as: a) 0.83 mg/L, exactly as it was defined for young adults in the adult equation, and b) a more complex QCysC-age relationship based on 4th degree cystatin C-age polynomials after evaluation of data from Uppsala, Stockholm and Canada and aggregated data from Germany. The EKFCCysC equation was then validated in an independent dataset in European children (n = 2,293) with measured GFR, creatinine, cystatin C, age, height and sex available. RESULTS: The EKFCCysC with the simple QCysC-value of 0.83 had a bias of -7.6 [95%CI -8.4;-6.5] mL/min/1.73 m2 and a P30-value of 85.8% [95%CI 84.4;87.3] equal to the EKFCCysC with the more complex 4th degree QCysC-value. The arithmetic mean of the EKFCCrea and EKFCCysC with the simple QCysC of 0.83 had a bias of -4.0 [95%CI -4.5;-3.1] mL/min/1.73 m2 and P30 of 90.4% [95%CI 89.2;91.6] similar to using the more complex 4th degree QCysC-polynomial. CONCLUSION: Using exactly the same QCysC of 0.83 mg/L, the adult EKFCCysC can easily be extended to children, with some bias but acceptable P30-values. The arithmetic mean of EKFCCrea and EKFCCysC results in bias closer to zero and P30 slightly over 90%.

Performance of creatinine-based equations to estimate glomerular filtration rate in White and Black populations in Europe, Brazil and Africa.

BACKGROUND: A new Chronic Kidney Disease Epidemiology Collaboration equation without the race variable has been recently proposed (CKD-EPIAS). This equation has neither been validated outside USA nor compared with the new European Kidney Function Consortium (EKFC) and Lund-Malmö Revised (LMREV) equations, developed in European cohorts. METHODS: Standardized creatinine and measured glomerular filtration rate (GFR) from the European EKFC cohorts (n = 13 856 including 6031 individuals in the external validation cohort), from France (n = 4429, including 964 Black Europeans), from Brazil (n = 100) and from Africa (n = 508) were used to test the performances of the equations. A matched analysis between White Europeans and Black Africans or Black Europeans was performed. RESULTS: In White Europeans (n = 9496), both the EKFC and LMREV equations outperformed CKD-EPIAS (bias of -0.6 and -3.2, respectively versus 5.0 mL/min/1.73 m², and accuracy within 30% of 86.9 and 87.4, respectively, versus 80.9%). In Black Europeans and Black Africans, the best performance was observed with the EKFC equation using a specific Q-value (= concentration of serum creatinine in healthy males and females). These results were confirmed in matched analyses, which showed that serum creatinine concentrations were different in White Europeans, Black Europeans and Black Africans for the same measured GFR, age, sex and body mass index. Creatinine differences were more relevant in males. CONCLUSION: In a European and African cohort, the performances of CKD-EPIAS remain suboptimal. The EKFC equation, using usual or dedicated population-specific Q-values, presents the best performance in the whole age range in the European and African populations included in this study.

Performance of creatinine-based equations to estimate glomerular filtration rate with a methodology adapted to the context of drug dosage adjustment.

AIM: The Cockcroft-Gault (CG) creatinine-based equation is still used to estimate glomerular filtration rate (eGFR) for drug dosage adjustment. Incorrect eGFR may lead to hazardous over- or underdosing. METHODS: In a cross-sectional analysis, CG was validated against measured GFR (mGFR) in 14 804 participants and compared with the Modification-of-Diet-in-Renal-Diseases (MDRD), Chronic-Kidney-Disease-Epidemiology (CKD-EPI), Lund-Malmö-Revised (LMR) and European-Kidney-Function-Consortium (EKFC) equations. Validation focused on bias, imprecision and accuracy (percentage of estimates within ±30% of mGFR, P30), overall and stratified for mGFR, age and body mass index at mGFR <60 mL/min, as well as classification in mGFR stages. RESULTS: The CG equation performed worse than the other equations, overall and in mGFR, age and BMI subgroups in terms of bias (systematic overestimation), imprecision and accuracy except for patients ≥65 years where bias and P30 were similar to MDRD and CKD-EPI, but worse than LMR and EKFC. In subjects with mGFR <60 mL/min and at BMI 18.5-25 kg/m2 , all equations performed similarly, and for BMI < 18.5 kg/m2 CG and LMR had the best results though all equations had poor P30-accuracy. At BMI ≥ 25 kg/m2 the bias of the CG increased with increasing BMI (+17.2 mL/min at BMI ≥ 40 kg/m2 ). The four more recent equations also classified mGFR stages better than CG. CONCLUSIONS: The CG equation showed poor ability to estimate GFR overall and in analyses stratified for mGFR, age and BMI. CG was inferior to correctly classify the patients in the mGFR staging compared to more recent creatinine-based equations.

[GFR estimation in children - age-adjusted creatinine makes the adult Lund-Malmö equation applicable in children and facilitates automatic GFR reporting from the clinical laboratory]. / Så kan formel för vuxna skatta glomerulär filtration hos barn.

Age-adjustment of creatinine, i.e. recalculation of childhood levels of creatinine to corresponding levels at 18 years of age and applied in the adult revised Lund-Malmö GFR equation led to markedly improved accuracy in Swedish children (n=1 718) at measured GFR <75 mL/min/1.73 m2 (n=318) and preserved high accuracy at ≥75 mL/min/1.73 m2 (n=1 400). The adjusted LMR equation performed as well as dedicated paediatric equations based on height. The proposed adjustment strategy has four strengths: (i) the original coefficients of the adult GFR equation can be used, (ii) the same equation can be used across the entire lifespan without artificial changes in estimated GFR when switching from paediatric to adult care, (iii) the lack of height factor makes it easier to automatically report estimated GFR by the laboratories and (iv) age-adjusted creatinine values imply that well-established creatinine reference intervals for adults can also be used for children.

Development and Validation of a Modified Full Age Spectrum Creatinine-Based Equation to Estimate Glomerular Filtration Rate : A Cross-sectional Analysis of Pooled Data.

BACKGROUND: The Chronic Kidney Disease in Children Study (CKiD) equation for children and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for adults are recommended serum creatinine (SCr)-based calculations for estimating glomerular filtration rate (GFR). However, these equations, as well as their combination, have limitations, notably the problem of implausible changes in GFR during the transition from adolescence to adulthood and overestimation of GFR in young adults. The full age spectrum (FAS) equation addresses these issues but overestimates GFR when SCr levels are low. OBJECTIVE: To develop and validate a modified FAS SCr-based equation combining design features of the FAS and CKD-EPI equations. DESIGN: Cross-sectional analysis with separate pooled data sets for development and validation. SETTING: Research and clinical studies (n = 13) with measured GFR available. PATIENTS: 11 251 participants in 7 studies (development and internal validation data sets) and 8378 participants in 6 studies (external validation data set). MEASUREMENTS: Clearance of an exogenous marker (reference method), SCr level, age, sex, and height were used to develop a new equation to estimate GFR. RESULTS: The new European Kidney Function Consortium (EKFC) equation is a FAS equation with low bias (-1.2 mL/min/1.73 m2 [95% CI, -2.7 to 0.0 mL/min/1.73 m2] in children and -0.9 mL/min/1.73 m2 [CI, -1.2 to -0.5 mL/min/1.73 m2] in adults) across the FAS (2 to 90 years) and SCr range (40 to 490 µmol/L [0.45 to 5.54 mg/dL]) and with fewer estimation errors exceeding 30% (6.5% [CI, 3.8% to 9.1%] in children and 3.1% [CI, 2.5% to 3.6%] in adults) compared with the CKiD and CKD-EPI equations. LIMITATION: No Black patients were included. CONCLUSION: The new EKFC equation shows improved accuracy and precision compared with commonly used equations for estimating GFR from SCr levels. PRIMARY FUNDING SOURCE: Swedish Research Council (Vetenskapsrådet).

Estimating glomerular filtration rate at the transition from pediatric to adult care.

The current Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommend the use of the bedside creatinine-based Chronic Kidney Disease in Children (CKiD) equation to estimate glomerular filtration rate (GFR) in children and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in adults. However, this approach causes implausible changes in estimated GFR (eGFR) at the transition from pediatric to adult care. We investigated the performance of the KDIGO strategy and various creatinine-based eGFR equations in a cross-sectional dataset of 5,764 subjects (age 10-30 years), using directly measured GFR (mGFR) as reference. We also evaluated longitudinal GFR slopes in 136 subjects who transitioned to adult care. Implausible changes in eGFR resulted from the large overestimation (bias=+21 mL/min/1.73m2) and poor precision of the CKD-EPI equation in the 18-20 year age group, compared to CKiD in the 16-18 year age group (bias=-2.7 mL/min/1.73m2), resulting in a mean change of 23 mL/min/1.73m2 at the transition to adult care. Averaging the CKiD and CKD-EPI estimates in young adults only partially mitigated this issue. The Full Age Spectrum equation (with and without height), the Lund-Malmö Revised equation, and an age-dependent weighted average of CKiD and CKD-EPI resulted in much smaller changes in eGFR at the transition (change of 0.6, -2.1, -0.9 and -1.8 mL/min/1.73m2, respectively). The longitudinal analysis revealed a significant difference in average GFR slope between mGFR and the KDIGO strategy (-2.2 vs. +2.9 mL/min/1.73 m2/year), which was not observed with the other approaches. These results suggest that the KDIGO recommendation for GFR estimation at the pediatric-adult care transition should be revisited.

Validation of standardized creatinine and cystatin C GFR estimating equations in a large multicentre European cohort of children.

BACKGROUND: Most validations of paediatric glomerular filtration rate (GFR) estimating equations using standardized creatinine (CR) and cystatin C (CYS) assays have comprised relatively small cohorts, which makes accuracy across subgroups of GFR, age, body mass index (BMI) and gender uncertain. To overcome this, a large cohort of children referred for GFR determination has been established from several European medical centres. METHODS: Three thousand four hundred eight measurements of GFR (mGFR) using plasma clearance of exogenous substances were performed in 2218 children aged 2-17 years. Validated equations included Schwartz-2009CR/2012CR/CYS/CR+CYS, FASCR/CYS/CR+CYS, LMRCR, Schwartz-LyonCR, BergCYS, CAPACYS, CKD-EPICYS, AndersenCR+CYS and arithmetic means of the best single-marker equations in explorative analysis. Five metrics were used to compare the performance of the GFR equations: bias, precision and three accuracy measures including the percentage of GFR estimates (eGFR) within ± 10% (P10) and ± 30% (P30) of mGFR. RESULTS: Three of the cystatin C equations, BergCYS, CAPACYS and CKD-EPICYS, exhibited low bias and generally satisfactory accuracy across all levels of mGFR; CKD-EPICYS had more stable performance across gender than the two other equations. Among creatinine equations, Schwartz-LyonCR had the best performance but was inaccurate at mGFR < 30 mL/min/1.73 m2 and in underweight patients. Arithmetic means of the best creatinine and cystatin C equations above improved bias compared to the existing composite creatinine+cystatin C equations. CONCLUSIONS: The present study strongly suggests that cystatin C should be the primary biomarker of choice when estimating GFR in children with decreased GFR. Arithmetic means of well-performing single-marker equations improve accuracy further at most mGFR levels and have practical advantages compared to composite equations.

Renal-limited vasculitis in children: a single-center retrospective long-term follow-up analysis.

Pauci-immune renal limited vasculitis (RLV) is a rare and aggressive autoimmune disease. We retrospectively analyzed the renal outcome of 6 children with biopsy proven RLV. Median age at diagnosis was 10.6 years (range 7.1 - 14.5) and the median follow-up was 4.4 years (range 2.3 - 6.6). At diagnosis, 5 patients were given induction therapy (methylprednisolone + cyclophosphamide pulses) followed by maintenance treatment (prednisolone + azathioprine) while 1 patient received maintenance treatment only. After induction, 4 patients either retained or recovered normal renal function, and 1 patient, in whom short-term plasma exchange was prescribed to try to rescue her renal function, became free from dialysis. Repeated biopsy showed no disease activity; however, renal scarring was evident in all renal specimens. At last follow-up, 2 patients had normal renal function, 3 patients had mild renal insufficiency, and 1 patient had advanced renal failure. In addition, 5 patients were treated for hypertension. Our case series suggests that an initial favorable response to immunosuppressive therapy might not necessarily prevent the occurrence of renal scarring and highlights the importance of regular follow-up.

Renal transplantation in infants and small children.

There are still concerns about renal transplantation in small children. The aim of this study was to identify prenatal data, underlying diseases, patient and graft survival, graft function and growth in young renal transplant recipients at our center. A retrospective analysis was performed on 50 kidney transplants performed during the period 1981-2008 in children weighing <13 kg. Their median age at transplantation was 1.4 (range 0.4-3.7) years and the median weight was 9.5 (3.4-12.1) kg. The underlying diseases were congenital in 88% of the patients and acquired in 12%. Ten-year patient survival was 88% (82% before 1998 and 95% since 1998). Ten-year graft survival was 82% (75 and 95%, respectively). Graft function (glomerular filtration rate) deteriorated from a mean of 75-48 ml/min/1.73 m(2) within 10 years. There was rapid catch-up growth within the first years post-transplant, from a median height of -2.44 standard deviation score (SDS) at transplantation to -0.74 SDS after 3 years. In small children, patient and graft survival were as good as those in older children. Renal function deteriorated during the first years post-transplant but stabilized within a few years. In most children, there was a substantial improvement in growth within the first years after transplantation.

Effects of prenatal food and micronutrient supplementation on child growth from birth to 54 months of age: a randomized trial in Bangladesh.

BACKGROUND: There is a lack of information on the optimal timing of food supplementation to malnourished pregnant women and possible combined effects of food and multiple micronutrient supplementations (MMS) on their offspring's growth. We evaluated the effects of prenatal food and micronutrient interventions on postnatal child growth. The hypothesis was that prenatal MMS and early invitation to food supplementation would increase physical growth in the offspring during 0-54 months and a combination of these interventions would further improve these outcomes. METHODS: In the large, randomized MINIMat trial (Maternal and Infant Nutrition Interventions in Matlab), Bangladesh, 4436 pregnant women were enrolled between November 2001 and October 2003 and their children were followed until March 2009. Participants were randomized into six groups comprising 30 mg Fe and 400 µg folic acid (Fe30F), 60 mg Fe and 400 µg folic acid (Fe60F) or MMS combined with either an early (immediately after identification of pregnancy) or a later usual (at the time of their choosing, i.e., usual care in this community) program invitation to food supplementation. The anthropometry of 3267 children was followed from birth to 54 months, and 2735 children were available for analysis at 54 months. RESULTS: There were no differences in characteristics of mothers and households among the different intervention groups. The average birth weight was 2694 g and birth length was 47.7 cm, with no difference among intervention groups. Early invitation to food supplementation (in comparison with usual invitation) reduced the proportion of stunting from early infancy up to 54 months for boys (p = 0.01), but not for girls (p = 0.31). MMS resulted in more stunting than standard Fe60F (p = 0.02). There was no interaction between the food and micronutrient supplementation on the growth outcome. CONCLUSIONS: Early food supplementation in pregnancy reduced the occurrence of stunting during 0-54 months in boys, but not in girls, and prenatal MMS increased the proportion of stunting in boys. These effects on postnatal growth suggest programming effects in early fetal life. TRIAL REGISTRATION NUMBER: ISRCTN: ISRCTN16581394.

Violence against women and increases in the risk of diarrheal disease and respiratory tract infections in infancy: a prospective cohort study in Bangladesh.

OBJECTIVE: To explore whether different forms of violence against women were associated with increased incidence rates of diarrhea and respiratory tract infections among infants. DESIGN: A 12-month follow-up study embedded in a food and micronutrient supplementation trial. SETTING: Rural Bangladesh. PARTICIPANTS: Pregnant women and their 3132 live-born children. MAIN EXPOSURE: Maternal exposure to physical, sexual, and emotional violence and level of controlling behavior in the family. MAIN OUTCOME MEASURES: Infants' risk of falling ill with diarrheal diseases and respiratory tract infections in relation to mothers' exposure to different forms of violence. Adjusted for household economic conditions, mother's education level, parity, and religion. RESULTS: Fifty percent of the women reported lifetime experience of family violence. Infants of mothers exposed to different forms of family violence had 26% to 37% higher incidence of diarrhea. Any lifetime family violence was positively associated with increased incidence of diarrheal diseases (adjusted rate ratio, 1.20; 95% confidence interval, 1.10-1.30) and lower respiratory tract infections (adjusted rate ratio, 1.31; 95% confidence interval, 1.17-1.46). Further, all forms of family violence were also independently positively associated with infant illness, and the highest incidence rates were found among the daughters of severely physically abused mothers. CONCLUSION: Family violence against women was positively associated with an increased risk of falling ill with diarrheal and respiratory tract infections during infancy. The present findings add to increasing evidence of the magnitude of public health consequences of violence against women.

Violence against women and the risk of under-five mortality: analysis of community-based data from rural Bangladesh.

AIM: To assess whether violence against women was associated with increased mortality risks for their daughters and sons before the age of 5. METHODS: Secondary analysis of longitudinal data from rural Bangladesh of 2691 live-born children in relation to their mother's experience of physical, sexual and emotional partner violence and level of controlling behaviour in marriage. Analyses were adjusted for potential confounders and stratified by gender. RESULT: Under five-mortality was 88 per 1000 in this cohort. Overall, there was no association between different forms of violence against women and under-five mortality. However, more educated women had an increased risk of under-five deaths of their female offspring if ever exposed to severe physical violence (adjusted hazard ratio 2.2, 95% CI 1.06-4.50) or to a high level of controlling behaviour in marriage (adjusted hazard ratio 2.5, 95% CI 1.30-4.90). Controlling behaviour in marriage increased the hazard ratios in a dose-response manner. Increased mortality risks were neither shown for offspring of women with low or no education nor for boys in any educational group. CONCLUSION: Severe physical violence and controlling behaviour in marriage were associated with higher under-five mortality among daughters of educated mothers in rural Bangladesh, indicating gender-biased consequences of partner violence for child mortality.

Violence against women increases the risk of infant and child mortality: a case-referent study in Nicaragua.

OBJECTIVE: To investigate the impact of violence against mothers on mortality risks for their offspring before 5 years of age in Nicaragua. METHODS: From a demographic database covering a random sample of urban and rural households in Le n, Nicaragua, we identified all live births among women aged 15-49 years. Cases were defined as those who had died before the age of 5 years, between January 1993 and June 1996. For each case, two referents, matched for sex and age at death, were selected from the database. A total of 110 mothers of the cases and 203 mothers of the referents were interviewed using a standard questionnaire covering mothers' experience of physical and sexual violence. The data were analysed for the risk associated with maternal experience of violence of infant and under-5 mortality. FINDINGS: A total of 61% of mothers of cases had a lifetime experience of physical and/or sexual violence compared with 37% of mothers of referents, with a significant association being found between such experiences and mortality among their offspring. Other factors associated with higher infant and under-5 mortality were mother's education (no formal education), age (older), and parity (multiparity). CONCLUSIONS: The results suggest an association between physical and sexual violence against mothers, either before or during pregnancy, and an increased risk of under-5 mortality of their offspring. The type and severity of violence was probably more relevant to the risk than the timing, and violence may impact child health through maternal stress or care-giving behaviours rather than through direct trauma itself.