Analysis of the association of leptin and adiponectin concentrations with metabolic syndrome in children: Results from the IDEFICS study.

BACKGROUND AND AIMS: Adipokines may play a role in the pathogenesis of the metabolic syndrome (MetS) in children. We aimed to evaluate the association of leptin, adiponectin, and its ratio (L/A ratio) with the metabolic syndrome (MetS) in a subsample of the IDEFICS (Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS) cohort. METHODS AND RESULTS: Leptin, adiponectin and MetS parameters were measured in a subsample of 1253 children (3-9.9 years) participating to the IDEFICS study, grouped as: Non-OW (underweight/normal weight) and OW/Ob (overweight/obese). MetS was defined using the sex- and age-specific cut-offs based on the distribution of MetS components in the IDEFICS cohort. The prevalence of the MetS among OW/Ob was 24.8% and 27.1% in boys and girls respectively, whereas ≤2% among Non-OW. OW/Ob had significantly higher leptin and L/A ratio as compared to Non-OW. Significantly higher leptin was found in OW/Ob with MetS as compared with OW/Ob without MetS. Significantly lower adiponectin was observed only in OW/Ob girls as compared to Non-OW. A 1SD increase in leptin and L/A ratio z-scores or a 1SD decrease in adiponectin z-score were significantly associated with higher risk of MetS. After adjustment for BMI or body fat mass (BFM) the association remained significant only for leptin. CONCLUSION: We showed that in European children, higher leptin concentration is associated with MetS, even after adjusting for BMI or BFM, confirming an early role of leptin in MetS, while the association of adiponectin with MetS seems be mediated by body fat in this age range.

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.

Does the FTO gene interact with the socioeconomic status on the obesity development among young European children? Results from the IDEFICS study.

BACKGROUND: Various twin studies revealed that the influence of genetic factors on psychological diseases or behaviour is more expressed in socioeconomically advantaged environments. Other studies predominantly show an inverse association between socioeconomic status (SES) and childhood obesity in Western developed countries. The aim of this study is to investigate whether the fat mass and obesity-associated (FTO) gene interacts with the SES on childhood obesity in a subsample (N = 4406) of the IDEFICS (Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS) cohort. METHODS: A structural equation model (SEM) is applied with the latent constructs obesity, dietary intakes, physical activity and fitness habits, and parental SES to estimate the main effects of the latter three variables and a FTO polymorphism on childhood obesity. Further, a multiple group SEM is used to explore whether an interaction effect exists between the single nucleotide polymorphism rs9939609 within the FTO gene and SES. RESULTS: Significant main effects are shown for physical activity and fitness (standardised [betacrc ](s) = -0.113), SES ([betacrc ](s) = -0.057) and the FTO homozygous AA risk genotype ([betacrc ](s) = -0.177). The explained variance of obesity is ~9%. According to the multiple group approach of SEM, we see an interaction between SES and FTO with respect to their effect on childhood obesity (Δχ(2) = 7.3, df = 2, P = 0.03). CONCLUSION: Children carrying the protective FTO genotype TT seem to be more protected by a favourable social environment regarding the development of obesity than children carrying the AT or AA genotype.

Reference values of bone stiffness index and C-terminal telopeptide in healthy European children.

BACKGROUND/OBJECTIVE: Quantitative ultrasound measurements and bone metabolic markers can help to monitor bone health and to detect impaired skeletal development. Population-based reference values for children may serve as a basis for preventive measures to reduce the risk of osteoporosis and osteoporotic fractures in later life. This is the first paper providing age-, sex- and height-specific reference values for bone stiffness index (SI) and serum carboxy-terminal cross-linking telopeptide of type I collagen (CTX) in healthy, apparently prepubertal children. SUBJECTS/METHODS: In the population-based IDEFICS baseline survey (2007-2008) and follow-up (2009-2010), 18,745 children from eight European countries were newly recruited. A total of 10,791 2-10.9-year-old and 1646 3-8.9-year-old healthy children provided data on SI of the right and left calcaneus and serum CTX, respectively. Furthermore, height and weight were measured. Percentile curves were calculated using the General Additive Model for Location Scale and Shape (GAMLSS) to model the distribution of SI and CTX depending on multiple covariates while accounting for dispersion, skewness, and the kurtosis of this distribution. RESULTS: SI was negatively associated with age and height in children aged 2-5 years, whereas a positive association was observed in children aged 6-10 years. The dip in SI occurred at older age for higher SI percentiles and was observed earlier in taller children than in smaller children. The CTX reference curves showed a linear-positive association with age and height. No major sex differences were observed for the SI and CTX reference values. CONCLUSION: These reference data lay the ground to evaluate bone growth and metabolism in prepubertal children in epidemiological and clinical settings. They may also inform clinical practice to monitor skeletal development and to assess adverse drug reactions during medical treatments.

Blood pressure reference values for European non-overweight school children: the IDEFICS study.

OBJECTIVES: To provide oscillometric blood pressure (BP) reference values in European non-overweight school children. DESIGN: Cross-sectional analysis from the IDEFICS study (www.ideficsstudy.eu) database. METHODS: Standardised BP and anthropometric measures were obtained from children aged 2 to 10.9 years, participating in the 2007-2008 and 2009-2010 IDEFICS surveys. Age- and height-specific systolic and diastolic pressure percentiles were calculated by GAMLSS, separately for boys and girls, in both the entire population (n=16,937) and the non-overweight children only (n=13,547). The robustness of the models was tested by sensitivity analyses carried out in both population samples. RESULTS: Percentiles of BP distribution in non-overweight children were provided by age and height strata, separately for boys and girls. Diastolic BP norms were slightly higher in girls than in boys for similar age and height, while systolic BP values tended to be higher in boys starting from age 5 years. Sensitivity analysis, comparing BP distributions obtained in all children with those of non-overweight children, showed that the inclusion of overweight/obese individuals shifted the references values upward, in particular systolic BP in girls at the extreme percentiles. CONCLUSIONS: The present analysis provides updated and timely information about reference values for BP in children aged 2 to <11 years that may be useful for monitoring and planning population strategies for disease prevention.

C-reactive protein reference percentiles among pre-adolescent children in Europe based on the IDEFICS study population.

OBJECTIVES: C-reactive protein (CRP) is involved in a wide range of diseases. It is a powerful marker for inflammatory processes used for diagnostic and monitoring purposes. We aimed to establish reference values as data on the distribution of serum CRP levels in young European children are scarce. SUBJECTS: Reference values of high-sensitivity CRP concentrations were calculated for 9855 children aged 2.0-10.9 years, stratified by age and sex. The children were recruited during the population-based European IDEFICS study (Identification and prevention of Dietary- and lifestyle-induced health Effects in Children and infantS) with 18 745 participants recruited from 2007 to 2010. RESULTS: In 44.1% of the children, CRP values were below or equal the detection limit of 0.2 mg/l. Median CRP concentrations showed a slight negative age trend in boys and girls, whereas serum CRP values were slightly higher in girls than in boys across all age groups. CONCLUSIONS: Our population-based reference values of CRP may guide paediatric practice as elevated values may require further investigation or treatment. Therefore, the presented reference values represent a basis for clinical evaluation and for future research on risk assessment of diseases associated with increased CRP levels among children.

Percentiles of fasting serum insulin, glucose, HbA1c and HOMA-IR in pre-pubertal normal weight European children from the IDEFICS cohort.

OBJECTIVES: The aim of this study is to present age- and sex-specific reference values of insulin, glucose, glycosylated haemoglobin (HbA1c) and the homeostasis model assessment to quantify insulin resistance (HOMA-IR) for pre-pubertal children. METHODS: The reference population consists of 7074 normal weight 3- to 10.9-year-old pre-pubertal children from eight European countries who participated in at least one wave of the IDEFICS ('identification and prevention of dietary- and lifestyle-induced health effects in children and infants') surveys (2007-2010) and for whom standardised laboratory measurements were obtained. Percentile curves of insulin (measured by an electrochemiluminescence immunoassay), glucose, HbA1c and HOMA-IR were calculated as a function of age stratified by sex using the general additive model for location scale and shape (GAMLSS) method. RESULTS: Levels of insulin, fasting glucose and HOMA-IR continuously show an increasing trend with age, whereas HbA1c shows an upward trend only beyond the age of 8 years. Insulin and HOMA-IR values are higher in girls of all age groups, whereas glucose values are slightly higher in boys. Median serum levels of insulin range from 17.4 and 13.2 pmol l(-1) in 3-<3.5-year-old girls and boys, respectively, to 53.5 and 43.0 pmol l(-1) in 10.5-<11-year-old girls and boys. Median values of glucose are 4.3 and 4.5 mmol l(-1) in the youngest age group and 49.3 and 50.6 mmol l(-1) in the oldest girls and boys. For HOMA-IR, median values range from 0.5 and 0.4 in 3-<3.5-year-old girls and boys to 1.7 and 1.4 in 10.5-<11-year-old girls and boys, respectively. CONCLUSIONS: Our study provides the first standardised reference values for an international European children's population and provides the, up to now, largest data set of healthy pre-pubertal children to model reference percentiles for markers of insulin resistance. Our cohort shows higher values of Hb1Ac as compared with a single Swedish study while our percentiles for the other glucose metabolic markers are in good accordance with previous studies.

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.

Percentile reference values for anthropometric body composition indices in European children from the IDEFICS study.

INTRODUCTION: To characterise the nutritional status in children with obesity or wasting conditions, European anthropometric reference values for body composition measures beyond the body mass index (BMI) are needed. Differentiated assessment of body composition in children has long been hampered by the lack of appropriate references. OBJECTIVES: The aim of our study is to provide percentiles for body composition indices in normal weight European children, based on the IDEFICS cohort (Identification and prevention of Dietary- and lifestyle-induced health Effects in Children and infantS). METHODS: Overall 18,745 2.0-10.9-year-old children from eight countries participated in the study. Children classified as overweight/obese or underweight according to IOTF (N=5915) were excluded from the analysis. Anthropometric measurements (BMI (N=12 830); triceps, subscapular, fat mass and fat mass index (N=11,845-11,901); biceps, suprailiac skinfolds, sum of skinfolds calculated from skinfold thicknesses (N=8129-8205), neck circumference (N=12,241); waist circumference and waist-to-height ratio (N=12,381)) were analysed stratified by sex and smoothed 1st, 3rd, 10th, 25th, 50th, 75th, 90th, 97th and 99th percentile curves were calculated using GAMLSS. RESULTS: Percentile values of the most important anthropometric measures related to the degree of adiposity are depicted for European girls and boys. Age- and sex-specific differences were investigated for all measures. As an example, the 50th and 99th percentile values of waist circumference ranged from 50.7-59.2 cm and from 51.3-58.7 cm in 4.5- to <5.0-year-old girls and boys, respectively, to 60.6-74.5 cm in girls and to 59.9-76.7 cm in boys at the age of 10.5-10.9 years. CONCLUSION: The presented percentile curves may aid a differentiated assessment of total and abdominal adiposity in European children.

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.

Polymorphisms of matrix metalloproteinase gene and adiposity indices in European children: results of the IDEFICS study.

OBJECTIVE: We investigated the relationship between matrix metalloproteinase 3 (MMP3) polymorphisms and adiposity indices in European children of the IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) project. SUBJECTS: A total of 16 224 Caucasian children (2-9 years) were recruited into a population-based survey from eight European countries. In all, 4540 children were randomly selected for genetic studies (T0); 3238 children were re-examined 2 years later (T1). Anthropometric measures were collected by standardized protocols at T0 and T1. RESULTS: Six variants of MMP3 gene were genotyped. Homozygotes for the variant A allele of rs646910 and for the H3 haplotype had higher hip circumference (P=0.002 and 0.001; age, sex and country adjusted) at T0. The association remained significant after false discovery rate (FDR) correction. At T1, subjects carrying rs646910 A/A genotype or H3/H3 diplotype showed significantly higher values of body mass index, waist and hip circumference and sum of tricipital and subscapular skinfolds, all associations remaining significant after FDR correction (P=0.020-0.048). CONCLUSIONS: We showed for the first time an association between the MMP3 rs646910 variant and indices of adiposity in European children, highlighting the involvement of metalloproteinase genes in adipose tissue remodeling and growth.

Validation of anthropometry and foot-to-foot bioelectrical resistance against a three-component model to assess total body fat in children: the IDEFICS study.

OBJECTIVE: To compare different field methods for estimating body fat mass with a reference value derived by a three-component (3C) model in pre-school and school children across Europe. DESIGN: Multicentre validation study. SUBJECTS: Seventy-eight preschool/school children aged 4-10 years from four different European countries. METHODS: A standard measurement protocol was carried out in all children by trained field workers. A 3C model was used as the reference method. The field methods included height and weight measurement, circumferences measured at four sites, skinfold measured at two-six sites and foot-to-foot bioelectrical resistance (BIA) via TANITA scales. RESULTS: With the exception of height and neck circumference, all single measurements were able to explain at least 74% of the fat-mass variance in the sample. In combination, circumference models were superior to skinfold models and height-weight models. The best predictions were given by trunk models (combining skinfold and circumference measurements) that explained 91% of the observed fat-mass variance. The optimal data-driven model for our sample includes hip circumference, triceps skinfold and total body mass minus resistance index, and explains 94% of the fat-mass variance with 2.44 kg fat mass limits of agreement. In all investigated models, prediction errors were associated with fat mass, although to a lesser degree in the investigated skinfold models, arm models and the data-driven models. CONCLUSION: When studying total body fat in childhood populations, anthropometric measurements will give biased estimations as compared to gold standard measurements. Nevertheless, our study shows that when combining circumference and skinfold measurements, estimations of fat mass can be obtained with a limit of agreement of 1.91 kg in normal weight children and of 2.94 kg in overweight or obese children.

Relation between bone mineral density, biological markers and anthropometric measures in 4-year-old children: a pilot study within the IDEFICS study.

OBJECTIVE: To investigate the relationship between bone mineral density (BMD), anthropometric characteristics, levels of biological markers for growth, bone turnover, insulin resistance and fat mass in 4-year-old Swedish children. METHODS: Descriptive study with 41 children (28 boys) who had anthropometric measurements and blood samples taken and heel dual-energy X-ray absorptiometry and laser (DXL) performed. The study participants were divided into groups of normal-weight (n=28) and overweight or obese (n=13) children. RESULTS: There was a significant difference in bone mineral content (BMC), BMD and bone mineral apparent density (BMAD) between overweight and normal-weight children. There was a significant positive correlation between BMC, BMD, BMAD and body mass index standard deviation scores (r=0.36, 0.34 and 0.29, P<0.01, respectively), waist circumference (r=0.32, 0.30, P<0.01 and r=0.26, P<0.05, respectively) and subscapular skinfold (r=0.26, 0.25 and 0.23, P<0.05, respectively). BMC and BMD correlated significantly with the sum of skinfold measures (r=0.25 and 0.23, P<0.05, respectively). Adiponectin was significantly inversely correlated with BMC, BMD and BMAD (r=-0.41, -0.40 and -0.41, P<0.01, respectively). Adiponectin was not correlated with skinfold measures. Multiple regression analysis revealed that adiponectin was an independent determinant of BMD, BMC and BMAD. CONCLUSION: To our knowledge, this is the first study investigating BMD assessed by heel-DXL in relation to anthropometry and metabolic markers in 4-year-old children. Adiponectin was significantly inversely correlated with bone mass parameters. Adiponectin may have an independent role in bone development and metabolism in young children.

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

OBJECTIVE: To evaluate the influence of a standardised sampling protocol and process quality across the different IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) centres on the results of the biochemical measurements. DESIGN: Baseline survey within the community-based intervention study. SUBJECTS: A total of 16,224 children, aged 2-8 years, enrolled in the IDEFICS baseline survey in 8 European countries. Venous or capillary blood samples were collected from 12,430 children, urine samples from 13,890 children and saliva samples from 14,019 children. METHODS: A set of quality indicators was recorded for the biological blood, urine and saliva samples collected during the IDEFICS study. Results of blood and urine measurements were analysed and stratified by selected quality indicators. RESULTS: Concentrations of biological markers in blood and urine measured during the IDEFICS baseline survey are associated with several quality indicators assessed in this study. Between-country variations of these biomarkers are described. It was confirmed that fasting has a big influence on the concentration of certain biomarkers. Biomarkers in morning urine samples may be erroneous if the study subjects void during the night or if samples are not taken from the very first morning urine. CONCLUSIONS: The analysed data underline that a standardised sampling protocol is of major importance, especially in multicentre studies, but non-compliance is ever present in spite of well-defined standard operation procedures. Deviations from the protocol should therefore always be documented to avoid error pertaining to the concentration of biological markers.

The relationship between paediatric calcaneal quantitative ultrasound measurements and dual energy X-ray absorptiometry (DXA) and DXA with laser (DXL) as well as body composition.

BACKGROUND: Quantitative ultrasound (QUS) is a quick, non-invasive and inexpensive method to measure bone strength. Moreover, the device is portable, which makes it easy to be used in the field. In contrast to other bone measuring techniques, QUS does not use any ionised radiation. However, the validity of QUS in the measurement of bone health and the relationship between QUS output and body composition have not been assessed in very young children. OBJECTIVE: To investigate the relationship between paediatric calcaneal QUS and both dual-energy X-ray absorptiometry (DXA) and calcaneal DXA with laser (DXL) and body composition parameters. SUBJECTS: A total of 37 Belgian children (10 boys and 27 girls; 4 to 8 years old) underwent a calcaneal QUS as well as a DXA scan. A total of 24 Swedish children (15 boys and 9 girls; 3 to 5 years old) underwent a calcaneal QUS as well as a heel DXL scan. The height and weight of all children were measured. RESULTS: The QUS stiffness index (SI) was significantly negatively correlated with bone mineral density (BMD) of the total body (r=-0.370, P=0.02). No significant correlations were found between the SI and DXL results. In the total sample, the SI showed a significant positive correlation with body mass index (BMI) (r=0.298, P=0.02), even after correction for age, gender and centre. In the Belgian sample, the SI was also significantly positively correlated with total body fat mass content (r=0.416, P=0.01) and body fat percentage (r=0.566, P<0.01) obtained by whole-body DXA. CONCLUSION: The SI measured by QUS does not correlate significantly with BMD values measured by DXA or DXL in 3- to 8-year-old children. However, there is a significant positive correlation between SI and BMI and body fat %.

Intra- and inter-observer reliability in anthropometric measurements in children.

INTRODUCTION: Studies such as IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) seek to compare data across several different countries. Therefore, it is important to confirm that body composition indices, which are subject to intra- and inter-individual variation, are measured using a standardised protocol that maximises their reliability and reduces error in analyses. OBJECTIVE: To describe the standardisation and reliability of anthropometric measurements. Both intra- and inter-observer variability of skinfold thickness (triceps, subscapular, biceps, suprailiac) and circumference (neck, arm, waist, hip) measurements were investigated in five different countries. METHODS: Central training for fieldwork personnel was carried out, followed by local training in each centre involving the whole survey staff. All technical devices and procedures were standardised. As part of the standardisation process, at least 20 children participated in the intra- and inter-observer reliability test in each centre. A total of 125 children 2-5 years of age and 164 children 6-9 years of age took part in this study, with a mean age of 5.4 (± 1.2) years. RESULTS: The intra-observer technical error of measurement (TEM) was between 0.12 and 0.47 mm for skinfold thickness and between 0.09 and 1.24 cm for circumference measurements. Intra-observer reliability was 97.7% for skinfold thickness (triceps, subscapular, biceps, suprailiac) and 94.7% for circumferences (neck, arm, waist, hip). Inter-observer TEMs for skinfold thicknesses were between 0.13 and 0.97 mm and for circumferences between 0.18 and 1.01 cm. Inter-observer agreement as assessed by the coefficient of reliability for repeated measurements of skinfold thickness and circumferences was above 88% in all countries. CONCLUSION: In epidemiological surveys it is essential to standardise the methodology and train the participating staff in order to decrease measurement error. In the framework of the IDEFICS study, acceptable intra- and inter-observer agreement was achieved for all the measurements.

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.

The IDEFICS validation study on field methods for assessing physical activity and body composition in children: design and data collection.

OBJECTIVE: To describe the design, measurements and fieldwork of the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) physical activity and body composition validation study, and to determine the potential and limitations of the data obtained. DESIGN: Multicentre validation study. SUBJECTS: A total of 98 children from four different European countries (age: 4-10 years). METHODS: An 8-day measurement protocol was carried out in all children using a collaborative protocol. Reference methods were the doubly labelled water method for physical activity, and a three- and a four-compartment model for body composition. Investigated field methods were accelerometers, a physical activity questionnaire and various anthropometric measurements. RESULTS: For the validation of physical activity field methods, it was possible to gather data from 83 to 89 children, laying the basis for age- and sex-specific results. The validation of body composition field methods is possible in 64-80 children and allows sex-specific analyses but has only limited statistical power in the youngest age group (<6 years). The amount of activity energy expenditure (AEE) varied between centres, sexes and age groups, with boys and older children having higher estimates of AEE. After normalisation of AEE by body weight, most group-specific differences diminished, except for country-specific differences. CONCLUSION: The IDEFICS validation study will allow age- and sex-specific investigation of questions pertaining to the validity of several field methods of body composition and physical activity, using established reference methods in four different European countries. From the participant analyses it can be concluded that the compliance for the investigated field methods was higher than that for the reference methods used in this validation study.

The IDEFICS community-oriented intervention programme: a new model for childhood obesity prevention in Europe?

BACKGROUND AND OBJECTIVES: The European Union-as well as other parts of the world-faces a major challenge of increasing incidence of overweight/obesity. In particular, the increase in childhood obesity gives rise to a strong imperative for immediate action. Yet, little is known about the effectiveness of community interventions, and further research in this field is needed. There is, however, a growing consensus that such research should start from the paradigm that the current living environments tend to counteract healthy lifestyles. Questioning these environments thoroughly can help to develop new pathways for sustainable health-promoting communities. Against this background, the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) study developed and implemented innovative community-oriented intervention programmes for obesity prevention and healthy lifestyle primarily in children aged 2-10 years in eight European countries: Sweden, Estonia, Germany, Belgium, Hungary, Italy, Spain and Cyprus. MATERIALS AND METHODS: The IDEFICS community-oriented intervention study mobilised an integrated set of interventional efforts at different levels of society, with the aim of facilitating the adoption of a healthy obesity-preventing lifestyle. The overall programme has been composed of 10 modules: three at community level, six at school level and one for parents. The main focus was on diet, physical activity and stress-coping capacity. The sphere of action encompassed both children and their (grand) parents, schools, local public authorities and influential stakeholders in the community. All materials for the interventions were centrally developed and culturally adapted. RESULTS: So far, the following has been achieved: focus group research, literature review and expert consultations were done in an early phase as a basis for the development of the intervention modules. The intervention mapping protocol was followed as guide for structuring the intervention research. The overall intervention programme's duration was 2 years, but a longer-term follow-up programme is under development. CONCLUSIONS: This large-scale European effort is expected to contribute significantly to the understanding of this major public health challenge.

Prevalence and determinants of childhood overweight and obesity in European countries: pooled analysis of the existing surveys within the IDEFICS Consortium.

OBJECTIVE: To pool and analyse, according to standardized criteria and using harmonized variables, the existing databases of surveys on childhood overweight and obesity carried out from 1995 to 2005 in different European countries by research groups participating in the IDEFICS project. METHODS: Detailed information from seven surveys in five European countries was collected. A common database was built after harmonization of the single studies regarding sample size and age distribution. Variables were critically reviewed and harmonized according to a common protocol. On the pooled database, descriptive comparative analyses on the prevalence of overweight/obesity and association analyses of these conditions with perinatal, parental and environmental factors were performed. RESULTS: Starting from total number of 74,871 children, data of 18,626 children were included in the common database (Belgium, n=1766; Cyprus, n=5540; Estonia, n=583; Italy, n=4480 and Sweden, n=6257). After the exclusion of children outside the defined age ranges (4-5 and 9-11 years), the analysis was conducted on 1738 younger and 12,923 older children. Relevant differences in the prevalence of overweight/obesity were observed between countries in both age groups, the highest values being observed in Italy. Age- and gender-related associations between the risk of obesity/overweight and perinatal, parental and environmental factors were observed. An increased risk of high blood pressure in overweight/obese children was consistently observed. CONCLUSIONS: The results of this collaborative work of European research centres, although providing potentially useful findings, confirmed that the validity of comparisons between communities depends critically on the comparability of the survey methods. To monitor the current epidemic of childhood obesity and develop appropriate prevention strategies, a coordinated European approach is needed to collect homogeneous sets of epidemiological data.