Relative validity and reproducibility of a parent-administered semi-quantitative FFQ for assessing food intake in Danish children aged 3-9 years

Objective: To assess the relative validity and reproducibility of the semi-quantitative FFQ (SFFQ) applied in the evaluation of a community intervention study, SoL-Bornholm, for estimating food intakes. Design: The reference measure was a 4 d estimated food record. The SFFQ was completed two times separated by a 1-month period in order to test reproducibility. Setting: The Capital Region and the Regional Municipality of Bornholm, Denmark. Subjects: A total of fifty-four children aged 3-9 years were enrolled in the study. Results: In terms of validity, the SFFQ generally overestimated intakes compared with the food records, especially for vegetables. For most intakes, the mean difference increased with increasing intake. Gross misclassification was on average higher for energy and nutrients (17 %) than for foods (8 %). Spearman correlation coefficients were significant for twelve out of fourteen intakes, ranging from 0.29 to 0.63 for foods and from 0.12 to 0.48 for energy and nutrients. Comparing the repeated SFFQ administrations, the intakes of the first SFFQ were slightly higher than those of the second SFFQ. Gross misclassification was low for most intakes; on average 6 % for foods and 8 % for energy and nutrients. Intra-class correlations were significant for all intakes, ranging from 0.30 to 0.82 for foods and from 0.46 to 0.81 for energy and nutrients. Conclusions: The results indicate that the SFFQ gives reproducible estimates. The relative validity of the SFFQ was low to moderate for most intakes but comparable to other studies among children.