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Validation Information: German EPIC FFQ1
The Relative Validity of Vitamin Intakes Derived from a Food Frequency Questionnaire Compared to 24-Hour Recalls and Biological Measurements: Results from the EPIC Pilot Study in Germany
Background:For the European Prospective Investigation into Cancer and Nutrition (EPIC) study Germany, a self-administered food frequency questionnaire (FFQ) was developed and tested for its relative validity and reproducibility in 1991/1992. Study participants were 92 potential cohort members. This paper reports results regarding retinol, carotenoids, tocopherols and ascorbic acid.
Methods:Study participants were invited to the study centre in Heidelberg once a month over one year. At each visit, a 24 hour recall was obtained. The FFQ was filled in twice with a 6-month interval (FFQ1, FFQ2). In addition, a questionnaire on general consumption frequencies of 14 broad food groups was completed. This information was combined with estimates derived from FFQ2 and frequency-corrected food and nutrient intakes were calculated (FFQcorr). Blood specimens were taken in winter and summer 1992.
Results:The intraclass correlation of the FFQ ranged from 0.65 to 0.67 for retinol, tocopherols, carotenoids, and ascorbic acid. Intake of carotenoids by FFQcorr showed de-attenuated Pearson correlation coefficients with blood values in the order of 0.37, and with recall data of 0.44. Respective correlations for retinol were 0.21 and 0.29, for tocopherols 0.18 and 0.52, and for ascorbic acid 0.36 and 0.69. Errors of FFQcorr and 24-hour diet recalls were not correlated.
Conclusions:In general, it was demonstrated that the FFQ was able to rank participants into biologically meaningful categories of intake or blood concentrations for carotenoids and ascorbic acid, but misclassification was higher for tocopherol and retinol.
Total number of nutrients validated: 4
Not all of the nutrients validated in the validation studies are included in the table below, as statistical data was only selected to be displayed for a number of nutrients, this included:
- Saturated Fat
- Mono-unsaturated Fat
- Poly-unsaturated Fat
- Non‐starch polysaccharides(NSP)
- Folic Acid
- Vitamin B12
- Vitamin C
- Fruit & Vegetables
- Urinary Nitrogen
To find information on the other validated nutrients please read the validation study.
- Macronutrients: 0
- Micronutrients: 4
|Comparator||Lifestage||Sex||Nutrient Measured||Mean Difference||Standard Deviation||Correlation Coefficient||Cohen's Kappa Coefficient||Percentage Agreement||Percentage Agreement Categories||Lower Limits of Agreement||Upper Limits of Agreement|
|24hr Recall||Adults||Both||Retinol (µg)||0.22 (P)|
|Vitamin C (mg)||0.61 (P)|
|Biomarkers||Adults||Both||Retinol (µg)||0.19 (P)|
|Vitamin C (mg)||0.24 (P)|
Some results have been calculated using statistical techniques based on the published data.
For further information on statistical terms click on Statistical tests used in validation studies
All correlations coefficients in the table are unadjusted unless stated otherwise. For adjusted correlation coefficients and other statistical methods used in the study e.g. paired t-tests, please read the validation articles.
- # Adjusted
- † Energy adjusted.
- ‡ For loge-transformed, energy-adjusted nutrient intakes.
- ^ Adjacent included.
- ᵟ Participants provided identical responses.
- (w) = Weighted.
Boeing H, Bohlscheid-Thomas S, Voss S, Schneeweiss S, Wahrendorf J. The relative validity of vitamin intakes derived from a food frequency questionnaire compared to 24-hour recalls and biological measurements: results from the EPIC pilot study in Germany. European Prospective Investigation into Cancer and Nutrition. International journal of epidemiology. 1997;26 Suppl 1:S82-90.