Validity and Reproducibility of a Semi-Quantitative Food Frequency Questionnaire Adapted to an Israeli Population

ABSTRACT

Assessment of individual representative dietary practices in epidemiologic research has long been a challenge. Given the differences in eating habits and availability of foods between populations, a study was set to test the reproducibility and validity of an Israeli-adapted semi-quantitative food frequency questionnaire (SFFQ) used in case-control studies of cancer etiology.

Two hundred volunteers between the ages 22-60 were randomly assigned to either complete an SFFQ independently or by nutritionist interview. Participants were then asked to fill out a 3-day food record (FR). SSFQ was repeated 3 months later. Reliability of the repeated SSFQ was examined using Pearson correlations; paired t-tests and Mann-Whitney Rank Test were used to measure reliability and validity of the SFFQ.

Overall, there was >85% agreement ± 1 category between the two encounters in over 75% of the food items. Percent of calories from proteins, fats and carbohydrates were similar for both self-administered and interviewed groups. The majority of correlations between the 1^st and 2^nd SSFQs for the micronutrients were above 0.75. No differences were noted in percent energy from proteins, fats or carbohydrates between self-administered and interviewer-assisted SSFQ and FR.

The Israeli FFQ was found in our study to be highly reproducible and valid compared to a dietary record.

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