The IDEFICS/I.Family Studies: Design and Methods of a Large European Child Cohort
Many unfavourable health outcomes such as excess body weight and resulting cardiovascular and metabolic sequelae have developmental origins and track into adulthood. The IDEFICS and I.Family studies investigated the impact of dietary, behavioural and socioeconomic factors on non-communicable chronic diseases in a large diverse sample of European children. The baseline examination of 16,229 children aged 2–9.9 years (mean age: 6.0 years; standard deviation: 1.8) from Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain and Sweden took place between September 2007 and June 2008. Two years later, 11,041 (68%) of these children and 2555 newly recruited children participated in the second round of examinations (mean age: 7.9 years; standard deviation: 1.9) where the same examination protocols were utilised as at baseline. In the interval between the two surveys, the children participated in a controlled trial of a community-oriented primary prevention programme to reduce overweight and obesity. A third round of examinations was conducted in 2013/2014 (mean age: 10.9 years; standard deviation: 2.9) to investigate the influence of familial characteristics on the children’s development with focus on diet and health outcomes. For this, we also invited siblings and at least one parent of the index child. Parents reported sociodemographic, behavioural, medical, nutritional and other lifestyle data for their younger children, themselves and their families while adolescents reported for themselves. Physical examinations of the offspring included anthropometry, blood pressure, heel ultrasonography, physical fitness, accelerometry as well as the collection of DNA from saliva and physiological markers in blood and urine. The built environment, sensory taste perception, neuropsychological traits and other characteristics presumably influencing children’s food choice (e.g. fMRI) as well as consumer behaviour were studied in subgroups. By covering the time from early childhood until adolescence, the studies allow the investigation of sensitive developmental periods using a life-course approach. The data set is enriched by further information from the pre-, peri- and postnatal phase gathered from registries and by self-report. The inclusion of parents and siblings and the assessment of peer groups enable the I.Family study to investigate the children as members of families and other social networks.
The development of instruments, the baseline data collection and the first follow-up work as part of the IDEFICS study (www.idefics.eu) were financially supported by the European Commission within the Sixth RTD Framework Programme Contract No. 016181 (FOOD). The most recent follow-up including the development of new instruments and the adaptation of previously used instruments was conducted in the framework of the I.Family study (www.ifamilystudy.eu) which was funded by the European Commission within the Seventh RTD Framework Programme Contract No. 266044 (KBBE 2010–14).
We thank all families for participating in the extensive examinations of the IDEFICS and I.Family studies. We are also grateful for the support from school boards, headmasters and communities.
Statement of Ethics
Approval by the appropriate Ethics Committees was obtained by each of the eight centres doing the field work. Study children did not undergo any procedure before both they and their parents had given consent for examinations, collection of samples, subsequent analysis and storage of personal data and collected samples. Study subjects and their parents could consent to single components of the study while abstaining from others. A common data protection protocol ensuring confidentiality of all collected data was approved by all survey centres. Access to study data is only granted to persons who have committed themselves to our confidentiality rules in writing.
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