Relative validity and reliability of an FFQ in youth with type 1 diabetes

Abstract

AbstractObjectiveTo evaluate the relative validity and reliability of the SEARCH FFQ that was modified from the Block Kids Questionnaire.DesignStudy participants completed the eighty-five-item FFQ twice plus three 24 h dietary recalls within one month. We estimated correlations between frequencies obtained from participants with the true usual intake for food groups and nutrients, using a two-part model for episodically consumed foods and measurement error adjustment.SettingThe multi-centre SEARCH for Diabetes in Youth Nutrition Ancillary Study.SubjectsA subgroup of 172 participants aged 10–24 years with type 1 diabetes.ResultsThe mean correlations, adjusted for measurement error, of food groups and nutrients between the FFQ and true usual intake were 0·41 and 0·38, respectively, with 57 % of food groups and 70 % of nutrients exhibiting correlations >0·35. Correlations were high for low-fat dairy (0·80), sugar-sweetened beverages (0·54), cholesterol (0·59) and saturated fat (0·51), while correlations were poor for high-fibre bread and cereal (0·16) and folate (0·11). Reliability of FFQ intake based on two FFQ administrations was also reasonable, with 54 % of Pearson correlation coefficients ≥0·5. Reliability was high for low-fat dairy (0·7), vegetables (0·6), carbohydrates, fibre, folate and vitamin C (all 0·5), but less than desirable for low-fat poultry and high-fibre bread, cereal, rice and pasta (0·2–0·3).ConclusionsWhile there is some room for improvement, our findings suggest that the SEARCH FFQ performs quite well for the assessment of many nutrients and food groups in a sample of youth with type 1 diabetes.