Reproducibility and relative validity of a food frequency questionnaire for a diet-related study in a rural Chinese population

BACKGROUND: This study aimed to assess the reproducibility and validity of a food frequency questionnaire (FFQ) developed for diet-related studies in a rural population. METHODS: One hundred fifty-four healthy residents were interviewed with a 76-item FFQ at baseline (FFQ1) and 1 month later (FFQ2) to assess reproducibility, and required to complete two three-day dietary recalls (DRs) between two FFQs to determine the validity by comparing DRs with FFQ1. RESULTS: Crude Spearman correlation coefficients between FFQ1 and FFQ2 ranged from 0.58 to 0.92 and energy-adjusted coefficients ranged from 0.62 to 0.92; weighted kappa statistic covered a spectrum from 0.45 to 0.81, depicting moderate to good agreements. For validity, there were moderate to strong associations (0.40–0.68) in most nutrients and food between FFQ1 and DRs; weighted kappa statistic demonstrated fair to moderate agreements for nutrients and food (0.21–0.49). CONCLUSIONS: The results suggest that the FFQ has reasonably reproducibility and validity in measuring most nutrients and food intake, and it can be used to explore the dietary habits in studying the diet-disease relationship in Chinese rural populations.