Developing and evaluating the validity and reliability of the Iranian preschool food frequency questionnaire (IP-FFQ)

Abstract

IntroductionThis study aimed to assess the relative validity and reliability of a semi-quantitative food-frequency questionnaire (FFQ) among preschool children in Iran. MethodsA total of 161 children aged 4–6 years were enrolled in the validation phase, with a subsample of 120 subjects participating in the reliability study. A two-round Delphi study was conducted to assess content validity, and 24-hours dietary recall (24-HR) was used as reference for the criterion validity of the FFQ. Reliability was evaluated by intra-class correlation coefficients (ICCs) between results of two FFQs administered with eight weeks intervals. The Bland–Altman plot was used to examine the agreement between the FFQ-1 vs 24-HRs and FFQ-1 vs FFQ-2 for energy and nutrient intakes. ResultsThe Delphi showed satisfactory levels of Content Validity Ratio (0.84) and Content Validity Index (0.88), respectively. The Pearson’s correlation coefficients between FFQ-1 and 24-HRs showed low to moderate agreement, ranging from 0.06 for vitamin B12 to 0.45 for vitamin D. As for reliability, ICCs showed excellent agreement (>0.75) for all nutrients between repeated FFQs. Findings of the Bland–Altman plots showed that most data points fell within the 95 % limits of agreement (LOA) for all nutrients. The results confirm that the IP-FFQ has acceptable validity and good reliability to assess preschool children’s food intake. ConclusionThis questionnaire could be used in epidemiological studies and health sciences research, to implement evidence-based strategies and policies for optimal growth and heath amongst children.