Influence of sample collection and preanalytical sample processing on the analyses of biological markers in the European multicentre study IDEFICS

Pre-analytical aspects in metabolomics of human biofluids - sample collection, handling, transport, and storage

Metabolomics is the field of omics research that offers valuable insights into the complex composition of biological samples. It has found wide application in clinical diagnostics, disease investigation, therapy prediction, monitoring of treatment efficiency, drug discovery, or in-depth analysis of sample composition. A suitable study design constitutes the fundamental requirements to ensure robust and reliable results from the study data. The study design process should include a careful selection of conditions for each experimental step, from sample collection to data analysis. The pre-analytical variability that can introduce bias to the subsequent analytical process, decrease the outcome reliability, and confuse the final results of the metabolomics research, should also be considered. Herein, we provide key information regarding the pre-analytical variables affecting the metabolomics studies of biological fluids that are the most desirable type of biological samples. Our work offers a practical review that can serve and guide metabolomics pre-analytical design. It indicates pre-analytical factors, which can introduce artificial data variation and should be identified and understood during experimental design (through literature overview or analytical experiments).

The temporal relationship between parental concern of overeating and childhood obesity considering genetic susceptibility: longitudinal results from the IDEFICS/I.Family study

BACKGROUND

Many genes and molecular pathways are associated with obesity, but the mechanisms from genes to obesity are less well known. Eating behaviors represent a plausible pathway, but because the relationships of eating behaviors and obesity may be bi-directional, it remains challenging to resolve the underlying pathways. A longitudinal approach is needed to assess the contribution of genetic risk during the development of obesity in childhood. In this study we aim to examine the relationships between the polygenic risk score for body mass index (PRS-BMI), parental concern of overeating and obesity indices during childhood.

METHODS

The IDEFICS/I.Family study is a school-based multicenter pan-European cohort of children observed for 6 years (mean ± SD follow-up 5.8 ± 0.4). Children examined in 2007/2008 (wave 1) (mean ± SD age: 4.4 ± 1.1, range: 2-9 years), in 2009/2010 (wave 2) and in 2013/2014 (wave 3) were included. A total of 5112 children (49% girls) participated at waves 1, 2 and 3. For 2656 children with genome-wide data we constructed a PRS based on 2.1 million single nucleotide polymorphisms. Z-score BMI and z-score waist circumference (WC) were assessed and eating behaviors and relevant confounders were reported by parents via questionnaires. Parental concern of overeating was derived from principal component analyses from an eating behavior questionnaire.

RESULTS

In cross-lagged models, the prospective associations between z-score obesity indices and parental concern of overeating were bi-directional. In mediation models, the association between the PRS-BMI and parental concern of overeating at wave 3 was mediated by baseline z-BMI (β = 0.16, 95% CI: 0.10, 0.21) and baseline z-WC (β = 0.17, 95% CI: 0.11, 0.23). To a lesser extent, baseline parental concern of overeating also mediated the association between the PRS-BMI and z-BMI at wave 3 (β = 0.10, 95% CI: 0.07, 0.13) and z-WC at wave 3 (β = 0.09, 95% CI: 0.07, 0.12).

CONCLUSIONS

The findings suggest that the prospective associations between obesity indices and parental concern of overeating are likely bi-directional, but obesity indices have a stronger association with future parental concern of overeating than vice versa. The findings suggest parental concern of overeating as a possible mediator in the genetic susceptibility to obesity and further highlight that other pathways are also involved. A better understanding of the genetic pathways that lead to childhood obesity can help to prevent weight gain.

TRIAL REGISTRATION

Registry number: ISRCTN62310987 Retrospectively registered 17 September 2018.

Evaluation of Existing Methods for Human Blood mRNA Isolation and Analysis for Large Studies

AIMS

Prior to implementing gene expression analyses from blood to a larger cohort study, an evaluation to set up a reliable and reproducible method is mandatory but challenging due to the specific characteristics of the samples as well as their collection methods. In this pilot study we optimized a combination of blood sampling and RNA isolation methods and present reproducible gene expression results from human blood samples.

METHODS

The established PAXgeneTM blood collection method (Qiagen) was compared with the more recent TempusTM collection and storing system. RNA from blood samples collected by both systems was extracted on columns with the corresponding Norgen and PAX RNA extraction Kits. RNA quantity and quality was compared photometrically, with Ribogreen and by Real-Time PCR analyses of various reference genes (PPIA, β-ACTIN and TUBULIN) and exemplary of SIGLEC-7.

RESULTS

Combining different sampling methods and extraction kits caused strong variations in gene expression. The use of PAXgeneTM and TempusTM collection systems resulted in RNA of good quality and quantity for the respective RNA isolation system. No large inter-donor variations could be detected for both systems. However, it was not possible to extract sufficient RNA of good quality with the PAXgeneTM RNA extraction system from samples collected by TempusTM collection tubes. Comparing only the Norgen RNA extraction methods, RNA from blood collected either by the TempusTM or PAXgeneTM collection system delivered sufficient amount and quality of RNA, but the TempusTM collection delivered higher RNA concentration compared to the PAXTM collection system. The established Pre-analytix PAXgeneTM RNA extraction system together with the PAXgeneTM blood collection system showed lowest CT-values, i.e. highest RNA concentration of good quality. Expression levels of all tested genes were stable and reproducible.

CONCLUSIONS

This study confirms that it is not possible to mix or change sampling or extraction strategies during the same study because of large variations of RNA yield and expression levels.

Efficacy of neck circumference to identify metabolic syndrome in 3-10 year-old European children: Results from IDEFICS study

BACKGROUND AND AIMS

Several studies demonstrated that larger neck circumference (NC) in children and adolescents may help to identify obesity and cardio-metabolic abnormalities. We aimed to evaluate the correlation between NC and metabolic syndrome (MetS) risk factors and to determine the utility of this anthropometric index to identify MetS in European children.

METHODS AND RESULTS

The present cross-sectional analysis includes 15,673 children (3-10 years) participating in the IDEFICS study. A continuous MetS (cMetS) score was calculated summing age and sex standardized z-scores of specific MetS risk factors. Receiver Operating Characteristic analysis, stratified by one-year age groups, was used to determine the ability of NC to identify children with unfavorable metabolic profile, corresponding to cMetS score ≥ 90th percentile. The areas under the curve values for NC associated with cMetS score values ≥ 90th percentile were significantly greater in girls than in boys (p < 0.001), except for 5 < 6 years group. For boys, optimal NC cut-off values ranged from 26.2 cm for the lowest age group (3 < 4 years), up to 30.9 cm for the highest age group (9 < 10 years). In girls, corresponding values varied from 24.9 cm to 29.6 cm.

CONCLUSION

The study demonstrated the efficacy of NC in identifying European children with an unfavorable metabolic profile.

Urinary Mineral Concentrations in European Pre-Adolescent Children and Their Association with Calcaneal Bone Quantitative Ultrasound Measurements

This study investigates differences and associations between urinary mineral concentrations and calcaneal bone measures assessed by quantitative ultrasonography (QUS) in 4322 children (3.1–11.9 years, 50.6% boys) from seven European countries. Urinary mineral concentrations and calcaneal QUS parameters differed significantly across countries. Clustering revealed a lower stiffness index (SI) in children with low and medium urinary mineral concentrations, and a higher SI in children with high urinary mineral concentrations. Urinary sodium (uNa) was positively correlated with urinary calcium (uCa), and was positively associated with broadband ultrasound attenuation and SI after adjustment for age, sex and fat-free mass. Urinary potassium (uK) was negatively correlated with uCa but positively associated with speed of sound after adjustment. No association was found between uCa and QUS parameters after adjustment, but when additionally adjusting for uNa, uCa was negatively associated with SI. Our findings suggest that urinary mineral concentrations are associated with calcaneal QUS parameters and may therefore implicate bone properties. These findings should be confirmed in longitudinal studies that include the food intake and repeated measurement of urinary mineral concentrations to better estimate usual intake and minimize bias.

Influence of physical fitness on cardio-metabolic risk factors in European children. The IDEFICS study

OBJECTIVE

The aim of the study was to assess the associations of individual and combined physical fitness components with single and clustering of cardio-metabolic risk factors in children.

SUBJECTS/METHODS

This 2-year longitudinal study included a total of 1635 European children aged 6-11 years. The test battery included cardio-respiratory fitness (20-m shuttle run test), upper-limb strength (handgrip test), lower-limb strength (standing long jump test), balance (flamingo test), flexibility (back-saver sit-and-reach) and speed (40-m sprint test). Metabolic risk was assessed through z-score standardization using four components: waist circumference, blood pressure (systolic and diastolic), blood lipids (triglycerides and high-density lipoprotein) and insulin resistance (homeostasis model assessment). Mixed model regression analyses were adjusted for sex, age, parental education, sugar and fat intake, and body mass index.

RESULTS

Physical fitness was inversely associated with clustered metabolic risk (P<0.001). All coefficients showed a higher clustered metabolic risk with lower physical fitness, except for upper-limb strength (β=0.057; P=0.002) where the opposite association was found. Cardio-respiratory fitness (β=-0.124; P<0.001) and lower-limb strength (β=-0.076; P=0.002) were the most important longitudinal determinants. The effects of cardio-respiratory fitness were even independent of the amount of vigorous-to-moderate activity (β=-0.059; P=0.029). Among all the metabolic risk components, blood pressure seemed not well predicted by physical fitness, while waist circumference, blood lipids and insulin resistance all seemed significantly predicted by physical fitness.

CONCLUSION

Poor physical fitness in children is associated with the development of cardio-metabolic risk factors. Based on our results, this risk might be modified by improving mainly cardio-respiratory fitness and lower-limb muscular strength.

Impact of a community based health-promotion programme in 2- to 9-year-old children in Europe on markers of the metabolic syndrome, the IDEFICS study

INTRODUCTION

One objective of 'Identification and prevention of Dietary-and lifestyle-induced health EFfects In Children and infantS', the IDEFICS study, was to implement a community-oriented childhood obesity prevention intervention in eight European countries.

OBJECTIVE

To assess the effect of an obesity primary prevention programme on metabolic markers.

METHODS

The study had a non-randomized cluster-experimental design. In each country, children were recruited from distinct communities serving as intervention and control regions. Health examinations were done during 2007-2008 before the intervention (T0 ) and during 2009-2010 (T1 ). Children with results available from T0 and T1 on blood pressure, waist circumference and at least one blood-marker (fasting glucose, insulin, HOMA-IR, HbA1c, HDL- and LDL-cholesterol, triglycerides, C-reactive protein) were included. A metabolic syndrome (MetS) score was calculated.

RESULTS

A total of 7,406 children (age 2-9.9 years) of the 16,228 participating at T0 provided the necessary data. No effect of the intervention was seen on insulin, HOMA-IR, CRP or the MetS score. Overall fasting glucose increased less in the intervention than in the control region, a pattern driven by three of the eight countries and more pronounced in children of parents with low education. Overall, HbA1c and waist circumference increased more and blood pressure less in the intervention regions.

CONCLUSION

We observed no convincing effect of the intervention on markers of the metabolic syndrome. We identified diverse patterns of change for several markers of uncertain relation to the intervention.

Association between bone stiffness and nutritional biomarkers combined with weight-bearing exercise, physical activity, and sedentary time in preadolescent children. A case-control study

Physical activity (PA) and micronutrients such as calcium (Ca), vitamin D (25OHD), and phosphate (PO) are important determinants of skeletal development. This case-control study examined the association of these nutritional biomarkers and different PA behaviours, such as habitual PA, weight-bearing exercise (WBE) and sedentary time (SED) with bone stiffness (SI) in 1819 2-9-year-old children from the IDEFICS study (2007-2008). SI was measured on the calcaneus using quantitative ultrasound. Serum and urine Ca and PO and serum 25OHD were determined. Children's sports activities were reported by parents using a standardised questionnaire. A subsample of 1089 children had accelerometer-based PA data (counts per minute, cpm). Moderate-to-vigorous PA (MVPA) and SED were estimated. Children with poor SI (below the 15th age-/sex-/height-specific percentile) were defined as cases (N=603). Randomly selected controls (N=1216) were matched by age, sex, and country. Odds ratios (OR) for poor SI were calculated by conditional logistic regression for all biomarkers and PA behaviour variables separately and combined (expressed as tertiles and dichotomised variables, respectively). ORs were adjusted for fat-free mass, dairy product consumption, and daylight duration. We observed increased ORs for no sports (OR=1.39, p<0.05), PA levels below 524 cpm (OR=1.85, p<0.05) and MVPA below 4.2% a day (OR=1.69, p<0.05) compared to WBE, high PA levels (<688 cpm) and high MVPA (6.7%), respectively. SED was not associated with SI. ORs were moderately elevated for low serum Ca and 25OHD. However, biomarkers were not statistically significantly associated with SI and did not modify the association between PA behaviours and SI. Although nutritional biomarkers appear to play a minor role compared to the osteogenic effect of PA and WBE, it is noteworthy that the highest risk for poor SI was observed for no sports or low MVPA combined with lower serum Ca (<2.5 mmol/l) or lower 25OHD (<43.0 nmol/l).

Metabolic syndrome in young children: definitions and results of the IDEFICS study

OBJECTIVE

To estimate the prevalence of the metabolic syndrome (MetS) using reference standards obtained in European children and to develop a quantitative MetS score and describe its distribution in children.

DESIGN AND METHODS

Population-based survey in eight European countries, including 18745 children 2.0 to 10.9 years, recruited during a second survey. Anthropometry (weight, height and waist circumference), blood pressure and serum-fasting triglycerides, HDL cholesterol, glucose and insulin were measured. We applied three widely accepted definitions of the pediatric MetS and we suggest a new definition, to guide pediatricians in decisions about close monitoring or even intervention (values of at least three of the MetS components exceeding the 90th or 95th percentile, respectively). We used a z-score standardisation to calculate a continuous score combining the MetS components.

RESULTS

Among the various definitions of MetS, the highest prevalence (5.5%) was obtained with our new definition requiring close observation (monitoring level). Our more conservative definition, requiring pediatric intervention gives a prevalence of 1.8%. In general, prevalences were higher in girls than in boys. The prevalence of metabolic syndrome is highest among obese children. All definitions classify a small percentage of thin or normal weight children as being affected. The metabolic syndrome score shows a positive trend with age, particularly regarding the upper percentiles of the score.

CONCLUSIONS

According to different definitions of pediatric MetS, a non-negligible proportion of mostly prepubertal children are classified as affected. We propose a new definition of MetS that should improve clinical guidance. The continuous score developed may also serve as a useful tool in pediatric obesity research. It has to be noted, however, that the proposed cutoffs are based on a statistical definition that does not yet allow to quantify the risk of subsequent disease.

Influence of breastfeeding on blood-cell transcript-based biomarkers of health in children

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

The expression of specific genes in peripheral blood cells (PBCs) may be used as biomarkers of the metabolic status. High levels of expression of CPT1A, SLC27A2, INSR, LEPR, FASN and PPARα in PBCs are indicative of a lower risk for the insulin resistant or dyslipidaemic state associated with obesity in children. Breastfeeding seems to confer protective effects against obesity and its related metabolic problems.

WHAT THIS STUDY ADDS

Children who had been breastfed showed higher expression levels of SLC27A2, FASN, PPARα and INSR in PBCs compared with formula-fed subjects. The relationship of the PBC transcript levels of SLC27A2, INSR, FASN and PPARα with insulin resistance and dyslipidaemia may be dependent on the type of infant feeding (breast vs. formula). The transcript levels of the mentioned biomarkers could be useful to distinguish the formula-fed children who are at higher risk of metabolic alterations.

BACKGROUND

Blood-cell transcripts have showed to be good biomarkers of metabolic alterations and their use in early detection and prevention of future disorders is promising.

OBJECTIVE

This study aimed to examine the relation between previously proposed transcriptional biomarkers of metabolic health (SLC27A2, CPT1A, FASN, PPARα, INSR, LEPR) in peripheral blood cells and the type of infant feeding in a subset of children from the IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) cohort.

SUBJECTS

A total of 237 children aged 2-9 years from eight European countries were studied.

RESULTS

Breastfed children showed higher expression levels of SLC27A2, FASN, PPARα and INSR, and lower risk of being overweight and of having high plasma triglyceride levels vs. formula-fed children. Besides, overweight formula-fed children presented higher HOMA-index than overweight breastfed children (1.90 vs. 1.62); however, this negative effect was absent in formula-fed children with high expression of SLC27A2. Moreover, formula-fed children with low expression of SLC27A2, FASN, PPARα and INSR presented higher triglyceride levels than subjects with high expression of these genes (77.7 mg dL(-1) vs. 44.8 mg dL(-1) ). This difference was absent in breastfed children.

CONCLUSIONS

Protective effects of breastfeeding are reflected in higher expression levels of SLC27A2, FASN, PPARα and INSR in blood cells. These biomarkers may also serve to discriminate the formula-fed children that are at higher risk of metabolic alterations.

World Endometriosis Research Foundation Endometriosis Phenome and Biobanking Harmonization Project: III. Fluid biospecimen collection, processing, and storage in endometriosis research

Objective

To harmonize standard operating procedures (SOPs) and standardize the recording of associated data for collection, processing, and storage of fluid biospecimens relevant to endometriosis.

Design

An international collaboration involving 34 clinical/academic centers and 3 industry collaborators from 16 countries on 5 continents.

Setting

In 2013, 2 workshops were conducted, followed by global consultation, bringing together 54 leaders in endometriosis research and sample processing worldwide.

Patient(s)

None.

Intervention(s)

Consensus SOPs were based on: [1] systematic comparison of SOPs from 18 global centers collecting fluid samples from women with and without endometriosis on a medium/large scale (publication on >100 cases), [2] literature evidence where available, or consultation with laboratory experts otherwise, and [3] several global consultation rounds.

Main Outcome Measure(s)

Standard recommended and minimum required SOPs for biofluid collection, processing, and storage in endometriosis research.

Result(s)

We developed recommended standard and minimum required SOPs for the collection, processing, and storage of plasma, serum, saliva, urine, endometrial/peritoneal fluid, and menstrual effluent, and a biospecimen data-collection form necessary for interpretation of sample-derived results.

Conclusion(s)

The Endometriosis Phenome and Biobanking Harmonisation Project SOPs allow endometriosis research centers to decrease variability in biofluid sample results, facilitating between-center comparisons and collaborations. The procedures are also relevant to research into other female conditions involving biofluid samples subject to cyclic reproductive influences. The consensus SOPs are based on the best available evidence; areas with limited evidence are identified as requiring further pilot studies. The SOPs will be reviewed based on investigator feedback, and through systematic tri-annual follow-up. Updated versions will be made available at: endometriosisfoundation.org/ephect.

Being macrosomic at birth is an independent predictor of overweight in children: results from the IDEFICS study

Fetal macrosomia is a risk factor for the development of obesity late in childhood. We retrospectively evaluated the relationship between maternal conditions associated with fetal macrosomia and actual overweight/obesity in the European cohort of children participating in the IDEFICS study. Anthropometric variables, blood pressure and plasma lipids and glucose were measured. Socio-demographic data, medical history and perinatal factors, familiar and gestational history, maternal and/or gestational diabetes were assessed by a questionnaire. Variables of interest were reported for 10,468 children (M/F = 5,294/5,174; age 6.0 ± 1.8 years, M ± SD). The sample was divided in four groups according to child birth weight (BW) and maternal diabetes: (1) adequate for gestational age offspring (BW between the 10th and 90th percentiles for gestational age) of mothers without diabetes (AGA-ND); (2) adequate for gestational age offspring of mothers with diabetes (AGA-D); (3) macrosomic offspring (BW > 90th percentile for gestational age) of mothers without diabetes (Macro-ND); (4) macrosomic offspring of mothers with diabetes (Macro-D). Children macrosomic at birth showed significantly higher actual values of body mass index, waist circumference, and sum of skinfold thickness. In both boys and girls, Macro-ND was an independent determinant of overweight/obesity, after the adjustment for confounders [Boys: OR = 1.7 95 % CI (1.3;2.2); Girls: OR = 1.6 95 % CI (1.3;2.0)], while Macro-D showed a significant association only in girls [OR = 2.6 95 % CI (1.1;6.4)]. Fetal macrosomia, also in the absence of maternal/gestational diabetes, is independently associated with the development of overweight/obesity during childhood. Improving the understanding of fetal programming will contribute to the early prevention of childhood overweight/obesity.

Understanding the links among neuromedin U gene, beta2-adrenoceptor gene and bone health: an observational study in European children

Neuromedin U, encoded by the NMU gene, is a hypothalamic neuropeptide that regulates both energy metabolism and bone mass. The beta-2 adrenergic receptor, encoded by the ADRB2 gene, mediates several effects of catecholamine hormones and neurotransmitters in bone. We investigated whether NMU single nucleotide polymorphisms (SNPs) and haplotypes, as well as functional ADRB2 SNPs, are associated with bone stiffness in children from the IDEFICS cohort, also evaluating whether NMU and ADRB2 interact to affect this trait. A sample of 2,274 subjects (52.5% boys, age 6.2±1.8 years) from eight European countries, having data on calcaneus bone stiffness index (SI, mean of both feet) and genotyping (NMU gene: rs6827359, rs12500837, rs9999653; ADRB2 gene: rs1042713, rs1042714), was studied. After false discovery rate adjustment, SI was significantly associated with all NMU SNPs. rs6827359 CC homozygotes showed the strongest association (recessive model, Δ = −1.8, p = 0.006). Among the five retrieved haplotypes with frequencies higher than 1% (range 2.0–43.9%), the CCT haplotype (frequency = 39.7%) was associated with lower SI values (dominant model, Δ = −1.0, p = 0.04) as compared to the most prevalent haplotype. A non-significant decrease in SI was observed in in ADRB2 rs1042713 GG homozygotes, while subjects carrying SI-lowering genotypes at both SNPs (frequency = 8.4%) showed much lower SI than non-carriers (Δ = −3.9, p<0.0001; p for interaction = 0.025). The association was more evident in preschool girls, in whom SI showed a curvilinear trend across ages. In subgroup analyses, rs9999653 CC NMU or both GG ADRB2 genotypes were associated with either lower serum calcium or β-CrossLaps levels (p = 0.01). This study in European children shows, for the first time in humans, a role for NMU gene through interaction with ADRB2 gene in bone strength regulation, more evident in preschool girls.

Physical activity and clustered cardiovascular disease risk factors in young children: a cross-sectional study (the IDEFICS study)

BACKGROUND

The relevance of physical activity (PA) for combating cardiovascular disease (CVD) risk in children has been highlighted, but to date there has been no large-scale study analyzing that association in children aged ≤9 years of age. This study sought to evaluate the associations between objectively-measured PA and clustered CVD risk factors in a large sample of European children, and to provide evidence for gender-specific recommendations of PA.

METHODS

Cross-sectional data from a longitudinal study in 16,224 children aged 2 to 9 were collected. Of these, 3,120 (1,016 between 2 to 6 years, 2,104 between 6 to 9 years) had sufficient data for inclusion in the current analyses. Two different age-specific and gender-specific clustered CVD risk scores associated with PA were determined. First, a CVD risk factor (CRF) continuous score was computed using the following variables: systolic blood pressure (SBP), total triglycerides (TG), total cholesterol (TC)/high-density lipoprotein cholesterol (HDL-c) ratio, homeostasis model assessment of insulin resistance (HOMA-IR), and sum of two skinfolds (score CRFs). Secondly, another CVD risk score was obtained for older children containing the score CRFs + the cardiorespiratory fitness variable (termed score CRFs + fit). Data used in the current analysis were derived from the IDEFICS ('Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS') study.

RESULTS

In boys <6 years, the odds ratios (OR) for CVD risk were elevated in the least active quintile of PA (OR: 2.58) compared with the most active quintile as well as the second quintile for vigorous PA (OR: 2.91). Compared with the most active quintile, older children in the first, second and third quintiles had OR for CVD risk score CRFs + fit ranging from OR 2.69 to 5.40 in boys, and from OR 2.85 to 7.05 in girls.

CONCLUSIONS

PA is important to protect against clustering of CVD risk factors in young children, being more consistent in those older than 6 years. Healthcare professionals should recommend around 60 and 85 min/day of moderate-to-vigorous PA, including 20 min/day of vigorous PA.

High-sensitivity C-reactive protein is a predictive factor of adiposity in children: results of the identification and prevention of dietary- and lifestyle-induced health effects in children and infants (IDEFICS) study

Background

Whereas cross‐sectional studies have shown that obesity is associated with increased C‐reactive protein (CRP) levels in children, little is known about the impact of low‐grade inflammation on body mass changes during growth.

Methods and Results

We assessed cross‐sectionally and longitudinally the association of high‐sensitivity (hs)‐CRP levels with overweight/obesity and related cardiometabolic risk factors in the Identification and prevention of Dietary‐ and lifestyle‐induced health Effects in Children and InfantS (IDEFICS) cohort. 16 224 children from 8 European countries (2 to 9 years) were recruited during the baseline survey (T0). After the exclusion of 7187 children because of missing hs‐CRP measurements and 2421 because of drug use during the previous week, the analysis was performed on 6616 children (Boys=3347; Girls=3269; age=6.3±1.7 years). Of them, 4110 were reexamined 2 years later (T1). Anthropometric variables, blood pressure, hs‐CRP, blood lipids, glucose and insulin were measured. The population at T0 was divided into 3 categories, according to the baseline hs‐CRP levels. Higher hs‐CRP levels were associated with significantly higher prevalence of overweight/obesity, body mass index (BMI) z‐score and central adiposity indices (P values all <0.0001), and with higher blood pressure and lower HDL‐cholesterol levels. Over the 2‐year follow‐up, higher baseline hs‐CRP levels were associated with a significant increase in BMI z‐score (P<0.001) and significantly higher risk of incident overweight/obesity.

Conclusions

Higher hs‐CRP levels are associated to higher body mass and overweight/obesity risk in a large population of European children. Children with higher baseline levels of hs‐CRP had a greater increase in BMI z‐score and central adiposity over time and were at higher risk of developing overweight/obesity during growth.

Food consumption and cardiovascular risk factors in European children: the IDEFICS study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Few studies addressing the relationship between food consumption and cardiovascular disease or metabolic risk have been conducted in children. Previous findings have indicated greater metabolic risk in children with high intakes of solid hydrogenated fat and white bread, and low consumption of fruits, vegetables and dairy products.

WHAT THIS STUDY ADDS

In a large multinational sample of 2 to 9 years old children, high consumption of sweetened beverages and low intake of nuts and seeds, sweets, breakfast cereals, jam and honey and chocolate and nut-based spreads were directly associated with increased clustered cardiovascular disease risk. These findings add new evidence to the limited literature available in young populations on the role that diet may play on cardiovascular health.

OBJECTIVE

To investigate food consumption in relation to clustered cardiovascular disease (CVD) risk.

METHODS

Children (n = 5548, 51.6% boys) from eight European countries participated in the IDEFICS study baseline survey (2007-2008). Z-scores of individual CVD risk factors were summed to compute sex- and age-specific (2-<6 years/6-9 years) clustered CVD risk scores A (all components, except cardiorespiratory fitness) and B (all components). The association of clustered CVD risk and tertiles of food group consumption was examined.

RESULTS

Odds ratio (OR) of having clustered CVD risk A increased in older children with higher consumption of chocolate and nut-based spreads (boys: OR = 0.46; 95% CI = 0.32-0.69; girls: OR = 0.60; 95% CI = 0.42-0.86), jam and honey (girls: OR = 0.45; 95% CI = 0.26-0.78) and sweets (boys: OR = 0.69; 95% CI = 0.48-0.98). OR of being at risk significantly increased with the highest consumption of soft drinks (younger boys) and manufactured juices (older girls). Concerning CVD risk score B, older boys and girls in the highest tertile of consumption of breakfast cereals were 0.41 (95% CI = 0.21-0.79) and 0.45 (95% CI = 0.22-0.93) times, respectively, less likely to be at risk than those in tertile 1.

CONCLUSIONS

High consumption of sugar-sweetened beverages and low intake of breakfast cereals, jam and honey, sweets and chocolate and nut-based spreads seem to adversely affect clustered CVD risk.

Gestational weight gain and adiposity, fat distribution, metabolic profile, and blood pressure in offspring: the IDEFICS project

OBJECTIVE

To investigate the association between gestational weight gain (GWG) and total adiposity, body fat distribution, blood pressure (BP), and metabolic profile in offspring.

DESIGN

Cross-sectional study.

METHODS

Body mass index (BMI), waist, subscapular and tricipital skinfolds, and BP were measured and blood samples drawn in 12 775 children (aged 2-9 years) from the IDEFICS cohort. Overweight/obesity was defined by IOTF criteria. Parents filled in a questionnaire investigating child and familiar medical history and lifestyle. A section was dedicated to pregnancy history (including GWG).

RESULTS

Anthropometric indices linearly and significantly increased across GWG tertiles (BMI z-score: tertile I =0.08, 0.03-0.13; tertile II =0.16, 0.12-0.21; tertile III =0.34, 0.28-0.40, P<0.01, mean, 95% CI) by analysis of covariance (ANCOVA) adjusted by child sex, age and practice of sport, birth weight, current maternal BMI, parental education, gestational age, age at delivery, alcohol and smoking during pregnancy, maternal diabetes mellitus, gestational hypertension, and breastfeeding duration. After inclusion of BMI z-score among covariates, HbA1c significantly increased across tertiles (P=0.009) while no differences were observed for BP, serum insulin, HOMA index, blood glucose and lipids. The adjusted risk of overweight/obesity significantly increased by 14 and 22% in tertiles II and III respectively, in comparison with tertile I by logistic regression analysis controlling for covariates.

CONCLUSION

Maternal GWG is an independent predictor of total adiposity and body fat distribution in offspring during infancy. Exposure to perinatal factors should be taken into account for early prevention of overweight and obesity.

Hair minerals and metabolic health in Belgian elementary school girls

Literature has repeatedly shown a relationship between hair minerals and metabolic health, although studies in children are currently lacking. This study aims to investigate hair levels of calcium (Ca), copper (Cu), magnesium (Mg), iron (Fe), phosphorus (P), and zinc (Zn) and their association with (1) overweight/obesity and (2) metabolic health in Flemish elementary school girls between 5 and 10 years old. Two hundred eighteen girls participated in this study as part of the baseline ChiBS project. Children were subjected to physical examinations, blood and hair sampling. Hair minerals were quantitatively determined via inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion. Body mass index (BMI) and body fat percentage (BF%) were studied as anthropometric parameters, and a metabolic score (including systolic and diastolic blood pressure, insulin resistance and non-high-density lipoprotein (non-HDL) cholesterol as parameters) was calculated, with higher scores indicating a more unhealthy metabolic profile. Hair Ca, Ca/Mg, and Ca/P positively correlated with the anthropometric parameters. An inverse correlation was observed between Ca, Mg, and Ca/P in hair and the metabolic score. Inverse correlations were also observed for individual metabolic parameters (i.e., diastolic blood pressure, homeostasis model assessment for insulin resistance, non-HDL cholesterol). In particular, girls with a total number of three or more metabolic parameters above the age-specific 75th percentile showed significantly reduced hair Ca, Mg, and Ca/P concentrations. This study showed reduced hair mineral concentrations in young girls with a more unhealthy metabolic profile. Positive associations were observed between some minerals and BMI and BF%.

From sleep duration to childhood obesity--what are the pathways?

Sleep duration has been identified as risk factor for obesity already in children. Besides investigating the role of fat mass (FM), this study addressed the question whether endocrine mechanisms act as intermediates in the association between sleep duration and overweight/obesity. Within the framework of the IDEFICS study, the present research was conducted in 609 German resident children aged 2-9 years with information on fasting insulin, C-reactive protein and cortisol levels next to anthropometric measurements and parental questionnaires. Emphasising methodological aspects, an age-specific measure of sleep duration was derived to account for alteration in sleep duration during childhood/period of growth. Multivariate linear regression and quantile regression models confirmed an inverse relationship between sleep duration and measures of overweight/obesity. The estimate for the association of sleep duration and body mass index (BMI) was approximately halved after adjustment for FM, but remained significant. The strength of this association was also markedly attenuated when adjusting for insulin mainly for the upper BMI quantiles (Q80, β = -0.36 vs. β = -0.26; Q95, β = -0.87 vs. β = -0.47). Adjustment for cortisol and CrP did not yield this attenuation.

CONCLUSION

The inverse relationship between sleep duration and BMI is mainly explained by the association between sleep duration and FM. Insulin may explain part of this association, in particular at the upper tail of the BMI distribution.

The IDEFICS cohort: design, characteristics and participation in the baseline survey

BACKGROUND

The European IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) study was set up to determine the aetiology of overweight, obesity and related disorders in children, and to develop and evaluate a tailored primary prevention programme.

OBJECTIVE

This paper focuses on the aetiological element of the multicentre study, the measures and examinations, sociodemographic characteristics of the study sample and proportions of participation.

DESIGN

Prospective cohort study with an embedded intervention study that started with a baseline survey in eight countries in 2007-2008.

SUBJECTS AND MEASUREMENTS

Baseline participants of the prospective cohort study were 16,224 children aged 2-9 years. Parents reported sociodemographic, behavioural, medical, nutritional and other lifestyle data for their children and families. Examinations of children included anthropometry, blood pressure, fitness, accelerometry, DNA from saliva and physiological markers in blood and urine. The built environment, sensory taste perception and other mechanisms of children's food choices and consumer behaviour were studied in subgroups.

RESULTS

Between 1507 and 2567, children with a mean age of 6.0 years and an even sex distribution were recruited from each country. Of them, 82% lived in two-parent families. The distribution of standardised income levels differed by study sample, with low-income groups being strongly represented in Cyprus, Italy and Germany. At least one 24-h dietary recall was obtained for two-thirds of the children. Blood pressure and anthropometry were assessed in more than 90%. A 3-day accelerometry was performed in 46%, motor fitness was assessed in 41%, cardiorespiratory fitness in 35% and ∼11% participated in taste perception tests. The proportion of children donating venous blood, urine and saliva was 57, 86 and 88%, respectively.

CONCLUSION

The IDEFICS cohort provides valuable data to investigate the interplay of social, environmental, genetic, physiological and behavioural factors in the development of major diet- and lifestyle-related disorders affecting children at present.