Study design & data collection

Study design & data collection

Timeline of the major study components (T0 = baseline survey; T1 = full follow-up; T2 = mail survey)

A cohort of 16 224 children aged 2–9 years from eight European countries (Sweden, Germany, Hungary, Italy, Cyprus, Spain, Belgium and Estonia) participated at the first population-based survey of the IDEFICS study. This first survey, defined as T0, was the baseline of the prospective cohort study with the largest European children’s cohort established to date and also represents the baseline measure for the IDEFICS intervention.

Country
Intervention
Non-Intervention
TOTAL
Germany
1,179

887

2,066
Sweden
902
907
1,809

Estonia

793
926
1,719
Spain
798
709
1,507
Cyprus
1,373
1,007
2,380
Italy
1,155
1,095
2,250
Hungary
1,277
1,290
2,567
Belgium
976
950
1,926
TOTAL
8,453
7,771
16,224

Study groups and sample size by country at baseline (T0)

A second survey (the follow-up, T1,) reassessed the children 2 years later to determine the associations between possible factors influencing health status observed at baseline and selected follow-up outcomes, and also for assessing short-term effects of the intervention, comparing children from control and intervention areas. By the end of T1 69% (=11,189) of the children who participated at T0 had participated, plus 2,433 new children who entered the corresponding schools or classes between T0 and T1.

Number of children recruited at T1 by country

A selection of morbidities observed at baseline (T0) was used for three retrospective case–control analyses in relation to overweight, insulin resistance (homeostasis model assessment (HOMA) and bone. Finally, a mailed questionnaire was completed by parents at the third survey (T2) to assess the sustainability of the intervention.

Study centre
Country
T0
T1
T2
T0 & T1
T0 & T1 & T2
ISA-CNR
Italy

2,250

1,738
1,827
1,548
1,311
NIHD
Estonia
1,719
1,765
1,840
1,334
1,223

REF

Cyprus
2,380
2,333
1,004
1,743
680
UGENT
Belgium
1,926
1,725
1,204
1,253
930
UGOT
Sweden
1,809
1,533
915
1,511
886
UNIHB
Germany
2,065
1,341
654
1,195
522
UPE
Hungary
2,569
1,920
1,815
1,247
891
UZAZ
Spain
1,507
1,241
1,009
1,207
971
TOTAL
16,225
13,596
10,268
11,038
7,414

Number of children eligible for analysis by country and time of examination; the last two columns give the number of children for whom measurements are available for the first two and for all three examinations, respectively

First results regarding the prevalence of overweight and obesity stratified by sex and country are displayed in the figures below. These results reveal a substantial variation of the corresponding prevalence values across study regions, with higher values in the South of Europe as compared to the North:

Prevalence of overweight and obesity in 2- to 9-year old boys (N=8,241) in the IDEFICS study (IOTF criteria)
Prevalence of overweight and obesity in 2- to 9-year old girls (N=7,947) in the IDEFICS study (IOTF criteria)

For learning about the study design of IDEFICS in detail we recommend following articles:

  • Ahrens W, Bammann K, Siani A, Buchecker K, De Henauw S, Iacoviello L, Hebestreit A, Krogh V, Lissner L, Mårild S, Molnár D, Moreno LA, Pitsiladis YP, Reisch L, Tornaritis M, Veidebaum T, Pigeot I; IDEFICS Consortium. The IDEFICS cohort: design, characteristics and participation in the baseline survey. Int J Obes (Lond). 2011 Apr;35 Suppl 1:S3-15. doi: 10.1038/ijo.2011.30.
    http://www.nature.com/ijo/journal/v35/n1s/full/ijo201130a.html
  • Ahrens W, Siani A, Adan R, De Henauw S, Eiben G, Gwozdz W, Hebestreit A, Hunsberger M, Kaprio J, Krogh V, Lissner L, Molnár D, Moreno LA, Page A, Picó C, Reisch L, Smith RM, Tornaritis M, Veidebaum T, Williams G, Pohlabeln H, Pigeot I, I.Family consortium. Cohort Profile: The transition from childhood to adolescence in European children-how I.Family extends the IDEFICS cohort. Int J Epidemiol. 2016 Dec 31. pii: dyw317. doi: 10.1093/ije/dyw317.
    http://ije.oxfordjournals.org/content/early/2016/12/31/ije.dyw317.extract

For the complete Final Publishable Report click here