Reproducibility and validity of a food-frequency questionnaire for use among low-income Brazilian workers

Abstract

Objectives: To assess the reproducibility and validity a 127-item, habitual intake, foodfrequency questionnaire (FFQ), developed for low-income and low-literacy Brazilian workers, by comparison with a 24-hour dietary recall (24-HDR). Design: The FFQ and 24-HDR were interviewer-administered at the local workplace to each subject twice, with a period of 6 months between estimates; and four 24-HDRs were conducted during the 4-month period between the two FFQs (FFQ1 and FFQ2). Reproducibility was tested by comparing mean nutrient intakes from the two FFQs. Validity was determined by comparing the mean nutrient intakes from the FFQs with the corresponding averages of the six 24-HDRs (reference method). Setting: Goiânia City, in Central West Brazil. Subjects: The study was based on 104 (62 women and 42 men) subjects, aged 18 to 60 years, who were randomly selected. Results: Dietary intake from the FFQ was higher than from the 24-HDR. Reproducibility was assessed by Pearson correlation coefficients for nutrients from FFQ1 and FFQ2, and ranged from 0.23 for retinol to 0.69 for total energy (mean 0.52). Intra-class coefficients for nutrients averaged by the 24-HDRs ranged from 0.29 for vitamin C to 0.76 for total energy; retinol was not significant. In the validation study, correlation between the FFQ and the 24-HDR ranged between 0.21 for vitamin C and 0.70 for total energy (mean 0.50). Adjusting for total energy lowered the coefficients, except for calcium, retinol and vitamin C. Coefficients increased with attenuation, ranging from 0.35 for carbohydrate to 0.65 for calcium. Conclusions: Results indicate that this questionnaire had satisfactory reproducibility and reasonable validity.

Development and validation of a food frequency questionnaire (FFQ-Porto Alegre) for adolescent, adult and elderly populations from Southern Brazil

“…The energy adjustment resulted nevertheless in a reduction in correlation coefficients for most nutrients, confirming previous findings 8,22 . The total energy adjustment was performed on the assumption that each participant reported similar nutrient intakes in both questionnaires 4 .…”

Validation of a food frequency questionnaire designed for adolescents in Salvador, Bahia, Brazil

“…The average correlation coefficient for the entire population studied was 0.52 23 . In another validation study conducted in Brazil, Fornes et al 26 found an average correlation coefficient of 0.50 for a population of adults; the same value that was found in the present study (0.50) for energy-adjusted coefficients.…”

Validation of a quantitative FFQ for a study of diet and risk of colorectal adenoma among Japanese Brazilians

“…Compared with an FFQ validation study among 104 Brazilian workers (23) , the present study demonstrated a slightly higher mean de-attenuated correlation coefficient for energy and the five nutrients in common between the two studies (0?42 v. 0?44).…”