Repeatability and relative validity of a quantitative food-frequency questionnaire among French adults

Abstract

BackgroundA 50-item self-administered food frequency questionnaire (FFQ) was developed for French adults, to assess the intake of energy, 10 macronutrients, 11 vitamins, and 11 minerals, and to be used in the context of a medical consultation.ObjectiveTo assess the repeatability and relative validity of this FFQ compared to a 7-day diet record (7-DR).DesignA total of 54 and 100 French adults were included in the repeatability and validation studies, respectively. Repeatability was assessed using two FFQs, the second carried out 3 weeks after the first. In the validation study, subjects first completed the FFQ, then the 7-DR the following week. Energy and nutrient intakes were compared using Pearson correlation. The degree of misclassification by the FFQ, compared to the 7-DR, was calculated by a contingency table of quintiles. Bland–Altman plots assessed the correlation between FFQ and 7-DR across the intake range.ResultsRepeatability for intake, explored by Pearson correlation, was 0.62–0.90 (median: 0.81). Relative validity, as determined by Pearson correlation for the nutrient intake derived from the FFQ and 7-DR, was 0.36–0.80 (0.64). The FFQ tended to report higher fiber and micronutrient intake than 7-DR. Misclassification into opposite quintiles ranged 0–6% (1%), whereas classification into same or adjacent quintiles ranged 59–83% (74%). Bland–Altman plots showed good agreement for most nutrients across the range of intake.ConclusionThis new FFQ showed a high repeatability and good relative validity, and thanks to its short length, should be a useful tool for rapidly evaluating the nutrient intake of French adults.

Validity and reproducibility of a food frequency questionnaire for adults of São Paulo, Brazil

“…The underestimation of the second FFQ compared to the first has been observed in other studies 11,12 . This may occur because the participants learn to respond to the questionnaire more accurately.…”

“…And it is possible to assume that the overestimation of consumption of four nutrients (carbohydrates, fiber, beta-carotene and vitamin C) by FFQ2 in comparison with 24HR happens by overestimating the consumption of sources of these nutrients, such as fruits, a common bias among individuals seeking for social approval of their diet 13 . It is noteworthy that the overestimation of nutrients can hide the poor consumption of the population 11 .…”

The relative validity and repeatability of an FFQ for estimating intake of zinc and its absorption modifiers in young and older Saudi adults

“…It should be noted that the time periods between the two FFQ in the latter studies were longer (from 3 months up to 1 year, compared with 1 month in the present study), which increased the likelihood of real changes in dietary habits and thus reduced correlation coefficients (37) .…”

“…Alternatively, the chore of completing the FFQ on a second or subsequent occasion may lead to less careful completion of the questionnaire. None the less, Lee et al (40) found that correlations between the first FFQ and the best estimate from dietary records were slightly lower than those between a third application of the FFQ and the dietary records, confirming the possibility of a learning effect (37) . This trend is confirmed by findings from the present study in which correlations between the second FFQ and the FR were slightly higher than those obtained from the first FFQ (results not shown).…”

Development and Validation of a Semi-Quantitative Food Frequency Questionnaire to Assess Dietary Intake of Turkish School-Aged Children

“…Both vitamin C and vitamin A were indicated by the poor correlation between the FFQ and DRs [Chen et al, 2004;Barrat et al, 2012]. In other study, the time reference can also refl ect changes in intake due to seasonality, so that lowering the true correlations of fruits and vegetables which are the main source of vitamins like vitamin C and caretonoids [Marchioni et al, 2007].…”