Development and validation of a quantitative food frequency questionnaire to assess free sugar intake among Sri Lankan preschool children.

The present study aims to develop a quantitative food frequency questionnaire (FFQ) to assess free sugar intake as a whole and at the food group levels, retrospectively, over the past 3 months among 4 to 5-year-old preschool children in the Colombo district, Sri Lanka. Then, to assess its reliability and relative validity. In the development phase, three 24-hour dietary recalls (24 hDRs) of 518 preschool children were collected from caregivers. Based on that, a 67-item FFQ was developed, including commonly consumed free sugar-containing food items. The validation study was conducted among another 108 preschool children. The relative validity of the FFQ was assessed by comparing it with the 24 hDRs. The test-retest reliability was assessed by repeated application of the FFQ to the same population after 6 weeks. Wilcoxon sign rank test, cross-classification with weighted Kappa statistic, Spearman rank correlation and Bland-Altman plots were used for comparison. Comparing the free sugar intake calculated by the two methods showed no difference (P = 0⋅13), a good correlation (0⋅89), good agreement in cross-classifying participants (78⋅4 % correctly classified) and a good agreement in Bland-Altman plots. Repeated application of the FFQ yielded; no differences in free sugar intake values (P = 0⋅45) a good correlation (0⋅71), acceptable agreement in cross-classifying participants (52⋅3 % correctly classified) and acceptable agreement in the Bland-Altman plot. Results were the same for all food groups. According to the results, the newly developed quantitative FFQ provides a relatively valid and reliable measure for quantifying free sugar intake among preschool children as a whole or by food group.