Relative validity and reproducibility of a food frequency questionnaire to evaluate food group intakes among Jordanian children and adolescents

Introduction: studies of the impact of diet on the prevention and occurrence of diseases in all life stages require a reliable and valid dietary assessment tool for assessing dietary intake. Objectives: this study aimed to develop and evaluate the relative validity and reproducibility of a culturally sensitive quantitative food frequency questionnaire (FFQ) to assess food group intake among Jordanian children and adolescents. Methods: the validation study was carried out on 136 children and adolescents aged between 6 and 18 years who enrolled from selected public and private schools. Fifty of these children and adolescents participated in the reproducibility phase. Food group intake from a quantitative FFQ was compared with food group intake from 24-hour dietary recalls (24h-DRs). Four 24-HRs were collected weekly for one month. Results: intraclass correlation coefficients between the two FFQs ranged from 0.18 for nuts to 0.98 for tea. De-attenuated and energy-adjusted correlations ranged from 0.08 for nuts to 0.95 for vegetable oils. On average, 46.6 % and 43.6 % of participants were ranked by the FFQ-1 and the 24h-DRs into the same quartile based on their crude and energy-adjusted food group intake, respectively. Bland-Altman plots showed a satisfactory agreement between the two methods for milk and milk products and vegetables. Conclusions: the findings of this study suggested that the developed FFQ has excellent reproducibility and good relative validity for most food groups.