Development and Validation of a Food Frequency Questionnaire for Population of Adolescents in Croatia

Abstract

Research background. Food frequency questionnaire (FFQ) is an important method for estimation of dietary intake in epidemiologic studies. The aim of the study was to develop FFQ and evaluate its relative validity for adolescents aged 12 to 18 years old. Experimental approach. FFQ was developed from previously validated Youth/Adolescent diet questionnaire (YAQ) by modifying it in order to include Croatian national foods. The final version of the FFQ (FFQ-m) was composed of 87 food items. The reference method was a set of two 3 day food records (3D-FR) administered twice during the 3 non-consecutive days, one month apart. The FFQ-m was administered approximately on the last day of the second applied dietary food record. Adolescents were recruited from randomly selected elementary and high schools in urban and rural areas of Croatia. FFQ-m was validated on a sample of 84 adolescents (70.2 % female). Nutritional intake from FFQ-m was analysed by Microsoft Office Excel 2007 worksheet derived from the PRODI 5.7 software database, while nutritional intake from 3D-FR was estimated using PRODI 5.7 software. Spearman correlation coefficients (r) and Bland-Altman method were used to assess validity of FFQ-m compared to 3D-FR. Anthropometric parameters were assessed in 78 adolescents. Results and conclusions. The mean nutrient intakes estimated by FFQ-m were higher than those of the 3D-FR. The average correlation coefficients for energy and nutrients in our validation study was 0.40. On average, 76.5 % of adolescents were classified in the same or adjacent quartile of nutrient intake. Bland-Altman analysis showed good agreement with all macronutrients and some micronutrients (sodium, phosphorus, potassium, calcium, magnesium, iron). A simple self-administrated questionnaire completed by adolescents is a valid tool for measuring energy and nutrient intake among adolescent population. Novelty and scientific contribution. This is the first FFQ developed and validated for population of adolescents in Croatia.