Validity and reproducibility of a food frequency interview in a multi-cultural epidemiologic study

PURPOSE: There is limited support for the validity and reproducibility of d ietary assessment in culturally diverse populations. The goal of this study was to evaluate the comparative validity and reproducibility of a Food Fre quency Questionnaire (FFQ) used in the observational, multi-culcural Insuli n Resistance Atherosclerosis Study (IRAS). METHODS: Women (n = 186) were approximately equally distributed by ethnicit y from one urban center (African Americans and non Hispanic whites) and one rural center (Hispanics and non Hispanic whites). The IRAS FFQ was modifie d from the National Cancer Institute Health Habits and History Questionnair e to include ethnic and regional foods. Validity was assessed by comparing dietary values, including supplements, obtained from the FFQ to the average intake estimated from a series of 8 24-hour dietary recalls collected by t elephone over the same 1 year period. Reproducibility was assessed among wo men who reported no change in their usual diet (n = 133) by comparing data from the original IRAS FFQ (in person) with the FFQ administered for the va lidity study (two to four years later, by telephone). RESULTS: Correlation coefficients for validity were statistically significa nt for most nutrients (mean r = 0.62 urban non Hispanic white, 0.61 rural n on-Hispanic whites, 0.50 African American, 0.41 Hispanic) and did not diffe r among subgroups of obesity or diabetes status. The median correlation coe fficient for the total sample was 0.49. Correlations were lower for women w ith less than 12 years of education (mean r = 0.30; median r = 0.25). The l ower correlations among Hispanics was largely explained by the lower educat ional attainment in that sample. For reproducibility, the mean correlation for nutrients evaluated was r = 0.62 (median r = 0.63) and did not differ f or subgroups. CONCLUSIONS: Although educational attainment must be considered, the IRAS F FQ appears to be reasonably valid and reliable in a diverse cohort. (C) 199 9 Elsevier Science Inc. All rights reserved.