Iris Pigeot

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 childrens 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.

Handbook of epidemiology

Preliminary Contents Preface - Wolfgang Ahrens, Iris Pigeot.Foreword - John M. Last.Introduction - Wolfgang Ahrens, Klaus Krickeberg, Iris Pigeot.1. Concepts and Methodological Approaches in Epidemiology 1.1. Basic Concepts - Kenneth J. Rothman, Sander Greenland1.2. Risk Measures - Jacques Benichou, Mari Palta1.3. Descriptive Studies - Donald M. Parkin, Freddie Bray1.4. Use of Routine Data and Disease Registries - Mans Rosen, Timo Hakulinen 1.5. Cohort Studies - Anthony B. Miller, David C. Goff Jr. Karin Bammann, Pascal Wild1.6. Case Control Studies - Norman E. Breslow1.7. Modern Study Designs - Philip H. Kass, Ellen B. Gold1.8. Intervention Trials - Silvia Franceschi, Martyn Plummer1.9. Confounding and Interaction - Neal Pearce, Sander Greenland1.10. Epidemiological Field Work in Population-Based Studies - Arlene Fink1.11. Exposure Assessment - Sylvaine Cordier, Patricia Stewart1.12. Design and Planning of Epidemiological Studies - Pascal Wild1.13. Quality Control and Good Epidemiological Practice - Preetha Rajaraman, Jonathan M. Samet 2. Statistical Methods in Epidemiology 2.1. Sample Size Determination in Epidemiologic Studies- Janet D. Elashoff, Stanley Lemeshow2.2. General Principles of Data Analysis - Heiko Becher2.3. Regression Mehtods for Epidemiologic Analysis - Sander Greenland2.4. Survival Analysis - Peter Sasieni2.5. Measurement Error - Jeffrey S. Buzas, Leonard A. Stefanski, Tor D. Tosteson2.6. Missing Data - Geert Molenberghs, Caroline Beunckens, Ivy Jansen, Herbert Thijs, Geert Verbeke, Michael G. Kenward2.7. Meta Analysis - Maria Blettner, Peter Schlattmann 2.8. Geographical Epidemiology - John F. Bithell3. Applications in Epidemiology 3.1. Social Epidemiology - Tarani Chandola, Michael Marmot3.2. Occupational Epidemiology - Franco Merletti, Dario Mirabelli, Lorenzo Richiardi 3.3. Environmental Epidemiology - Lothar Kreienbrock3.4. Nutritional Epidemiology - Dorothy Mackerras, Barrie M. Margetts3.5. Reproductive Epidemiology - JAA rn Olsen, Olga Basso3.6. Molecular Epidemiology - Paolo Vineis, Guiseppe Matullo, Marianne Berwick3.7. Genetic Epidemiology - Heike Bickeboller3.8. Clinical Epidemiology - Holger J. Schunemann, Gordon H. Guyatt 3.9. Pharmacoepidemiology - Edeltraut Garbe, Samy Suissa 3.10. Screening - Anthony B. Miller3.11. Prevention and Health Promotion - John W. Farquhar, Stephen P. Fortmann4. Research Areas in Epidemiology 4.1. Infectious Diseases - Susanne Straif-Bourgois, Raoult Ratard 4.2. Cardiovascular Diseases - Darwin R. Labarthe4.3. Cancer Epidemiology - Paolo Boffetta4.4. Musculoskeletal Disorders - Hilkka Riihimaki4.5. Health Systems Research - Thomas Schafer, Christian Gericke, Reinhard Busse4.6. Epidemiology in Developing Countries Part A: Klaus Krickeberg, Part B: Anita Kar, Asit Kumar Chakraborty4.7. Ethical Aspects of Epidemiological Research - Hubert G. Leufkens, Johannes J.M. van Delden

Prevalence of overweight and obesity in European children below the age of 10

Background:There is a lack of common surveillance systems providing comparable figures and temporal trends of the prevalence of overweight (OW), obesity and related risk factors among European preschool and school children. Comparability of available data is limited in terms of sampling design, methodological approaches and quality assurance. The IDEFICS (Identification and prevention of Dietary- and lifestyle-induced health Effects in Children and infantS) study provides one of the largest European data sets of young children based on state-of-the-art methodology.Objective:To assess the European distribution of weight status according to different classification systems based on body mass index (BMI) in children (2.0–9.9 years). To describe the prevalence of weight categories by region, sex, age and socioeconomic position.Design:Between 2007 and 2010, 18 745 children from eight European countries participated in an extensive, highly standardised protocol including, among other measures, anthropometric examinations and parental reports on socio-demographic characteristics.Results:The combined prevalence of OW/obesity ranges from more than 40% in southern Europe to less than 10% in northern Europe. Overall, the prevalence of OW was higher in girls (21.1%) as compared with boys (18.6%). The prevalence of OW shows a negative gradient with social position, with some variation of the strength and consistency of this association across Europe. Overall, population groups with low income and/or lower education levels show the highest prevalence of obesity. The use of different reference systems to classify OW results in substantial differences in prevalence estimates and can even reverse the reported difference between boys and girls.Conclusions:There is a higher prevalence of obesity in populations from southern Europe and in population groups with lower education and income levels. Our data confirm the need to develop and reinforce European public health policies to prevent early obesity and to reduce these health inequalities and regional disparities.

Assessment of diet, physical activity and biological, social and environmental factors in a multi-centre European project on diet- and lifestyle-related disorders in children (IDEFICS)

Obesity is a major public health problem in developed countries. We present a European project, called Identification and Prevention of Dietary and Lifestyle-induced Health Effects in Children and Infants (IDEFICS), that focuses on diet- and lifestyle-related diseases in children. This paper outlines methodological aspects and means of quality control in IDEFICS. IDEFICS will use a multicentre survey design of a population-based cohort of about 17,000 2- to 10-year-old children in nine European countries (Belgium, Cyprus, Estonia, Germany, Greece, Hungary, Italy, Spain and Sweden). The project will investigate the impact of dietary factors such as food intake and food preferences, lifestyle factors such as physical activity, psychosocial factors and genetic factors on the development of obesity and other selected diet- and lifestyle-related disorders. An intervention study will be set up in pre-school and primary school settings in eight of the survey centres. Standardised survey instruments will be designed during the first phase of the project and applied in the surveys by all centres. Standard operation procedures (SOPs) will be developed, as well as a plan for training the personnel involved in the surveys. These activities will be accompanied by a quality control strategy that will encompass the evaluation of process and result quality throughout the project. IDEFICS will develop comparable Europe-wide health indicators and instruments for data collection among young children. Establishment of a new European cohort within IDEFICS will provide a unique opportunity to document the development of the obesity epidemic in the current generation of young Europeans and investigate the impact of primary prevention in European children populations.

Establishment of a pharmacoepidemiological database in Germany: methodological potential, scientific value and practical limitations

We present a new population‐based pharmacoepidemiological (PE) database obtained from statutory health insurances (SHIs) that is able to generate signals, to monitor prescribed drugs and to describe drug utilisation. We discuss methodological features of the database and we assess to which degree this database reflects basic demographic characteristics and hospitalisation rates of the general population.

Socioeconomic factors and childhood overweight in Europe: results from the multi-centre IDEFICS study.

What is already known about this subject Overweight and obesity can be linked to different parental socioeconomic factors already in very young children. In Western developed countries, the association of childhood overweight and obesity and parental socioeconomic status shows a negative gradient. Ambiguous results have been obtained regarding the association between socioeconomic factors and childhood overweight and obesity in different countries and over time.

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 programmes 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.

Genetic associations of 115 polymorphisms with cancers of the upper aerodigestive tract across 10 european countries: The ARCAGE project

Cancers of the upper aerodigestive tract (UADT) include malignant tumors of the oral cavity, pharynx, larynx, and esophagus and account for 6.4% of all new cancers in Europe. In the context of a multicenter case-control study conducted in 14 centers within 10 European countries and comprising 1,511 cases and 1,457 controls (ARCAGE study), 115 single nucleotide polymorphisms (SNP) from 62 a priori-selected genes were studied in relation to UADT cancer. We found 11 SNPs that were statistically associated with UADT cancers overall (5.75 expected). Considering the possibility of false-positive results, we focused on SNPs in CYP2A6, MDM2, tumor necrosis factor (TNF), and gene amplified in squamous cell carcinoma 1 (GASC1), for which low P values for trend (P trend<0.01) were observed in the main effects analyses of UADT cancer overall or by subsite. The rare variant of CYP2A6 -47A>C (rs28399433), a phase I metabolism gene, was associated with reduced UADT cancer risk (P trend=0.01). Three SNPs in the MDM2 gene, involved in cell cycle control, were associated with UADT cancer. MDM2 IVS5+1285A>G (rs3730536) showed a strong codominant effect (P trend=0.007). The rare variants of two SNPs in the TNF gene were associated with a decreased risk; for TNF IVS1+123G>A (rs1800610), the P trend was 0.007. Variants in two SNPs of GASC1 were found to be strongly associated with increased UADT cancer risk (for both, P trend=0.008). This study is the largest genetic epidemiologic study on UADT cancers in Europe. Our analysis points to potentially relevant genes in various pathways.

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.

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.