Development, repeatability and validity regarding energy and macronutrient intake of a semi-quantitative food frequency questionnaire: Methodological considerations

Background and Aim: The aim of this work was to evaluate the repeatability and the validity of a food frequency questionnaire (FFQ), and to discuss the methodological framework of such procedures. Methods and Results: The semi-quantitative FFQ included 69 questions regarding the frequency of consumption of all main food groups and beverages usually consumed and 7 questions regarding eating behaviors. Five hundred individuals (37 +/- 15 yrs, 38% males) were recruited for the repeatability process, while another 432 (46 +/- 16 yrs, 40% males) also completed 3-Day Diaries (3DD) for the validation process. The repeatability of the FFQ was adequate for all food items tested (Kendall's tau-b: 0.26-0.67, p < 0.05), energy and macro-nutrients intake (energy adjusted correlation coefficients ranged between 0.56-0.69, p < 0.05). Moderate validity of the FFQ was observed for "dairy products", "fruit", "alcohol" and "stimulants" (tau-b: 0.31-0.60, p < 0.05), whereas low agreement was shown for "starchy products", "legumes", "vegetables", "meat", "fish", "sweets", "eggs", "fats and oils" (tau-b < 0.30, p < 0.05). The FFQ was also valid regarding energy and macronutrients intake. Sensitivity analyses by sex and BMI category (< or >= 25 kg/m(2)) showed similar validity of the FFQ for all food groups (apart from "fats and oils" intake), as well as energy and nutrient intake. Conclusion: The proposed FFQ has proven repeatable and relatively valid for foods' intake, and could therefore be used for nutritional assessment purposes. (C) 2010 Elsevier B. V. All rights reserved.