Relative validity and reproducibility of a quantitative FFQ for assessing nutrient intakes of vegetarians in Taiwan

Abstract

Objective: To assess the relative validity and reproducibility of the quantitative FFQ used in the Tzu Chi Health Study (TCHS). Design: The reproducibility was evaluated by comparing the baseline FFQ with the 2-year follow-up FFQ. The validity was evaluated by comparing the baseline FFQ with 3 d dietary records and biomarkers (serum folate and vitamin B 12 ). Median comparison, cross-classification and Spearman correlation with and without energy adjustment and deattenuation for day-to-day variation were assessed. Setting: TCHS is a prospective cohort containing a high proportion of true vegetarians and part-time vegetarians (regularly consuming a vegetarian diet without completely avoiding meat). Subject: Subsets of 103, seventy-eight and 1528 TCHS participants were included in the reproducibility, dietary record-validity and biomarker-validity studies, respectively. Results: Correlations assessing the reproducibility for repeat administrations of the FFQ were in the range of 0?46-0?65 for macronutrients and 0?35-0?67 for micronutrients; the average same quartile agreement was 40%. The correlation between FFQ and biomarkers was 0?41 for both vitamin B 12 and folate. Moderate to good correlations between the baseline FFQ and dietary records were found for energy, protein, carbohydrate, saturated and monounsaturated fat, fibre, vitamin C, vitamin A, K, Ca, Mg, P, Fe and Zn (average crude correlation: 0?47 (range: 0?37-0?66); average energy-adjusted correlation: 0?43 (range: 0?38-0?55); average energy-adjusted deattenuated correlation: 0?50 (range: 0?44-0?66)) with same quartile agreement rate of 39% (range: 35-45%), while misclassification to the extreme quartile was rare (average: 4% (range: 0-6%)). Conclusions: The FFQ is a reliable and valid tool to rank relative intake of major nutrients for TCHS participants.

Online Dietary Intake Estimation: Reproducibility and Validity of the Food4Me Food Frequency Questionnaire Against a 4-Day Weighed Food Record

“…Cross-classification analysis of repeated measures of intakes of energy, nutrients, and food groups indicated a high level of reproducibility with classification into quartiles of exact agreement plus adjacent averaging 92% for energy and nutrient intake and for food group intakes. Cross-classifications were within the range reported by previous studies [21,32,38]. Bland-Altman plots demonstrated a good level of reproducibility for energy-controlled total fat, protein, and carbohydrate intake, which reinforces evidence for the reliability of the Food4Me FFQ.…”

“…Ranks of energy and nutrient intake estimated using the Food4Me FFQ were highly comparable to the 4-day WFR with the percentage of individuals classified into quartiles of exact agreement and exact agreement plus adjacent averaging 40% and 80%, respectively. Previous studies comparing FFQ with food records have reported average exact agreement classifications between 34% and 49% [32,38,41] and exact agreement plus adjacent quartile classifications of 77% [21]. Estimates of intake showing disagreement between measurement tools in the present study were small and were comparable with the aforementioned studies.…”

Online Dietary Intake Estimation: The Food4Me Food Frequency Questionnaire

“…Cross-classification of daily energy and nutrient intakes showed good agreement between the two FFQs indicating that the online Food4Me FFQ generates ranks of dietary intakes that are highly comparable with the previously validated printed EPIC-Norfolk FFQ. Similar to many previous published studies, classification into exact plus adjacent quartiles ranged from 77% to 97% and exact disagreement/misclassification ranged between 0% and 5% [21,28,44,45]. Furthermore, Bland and Altman plots demonstrated an acceptable level of agreement between the two methods for energy and total fat and carbohydrate intakes as a percentage of total energy.…”

Vascular burden and brain aging in a senior volunteer cohort: A pilot study

“…We assessed dietary components using a 64-item quantitative food frequency questionnaire, previously validated among registered Tzu Chi volunteers [14]. We conducted in-person interviews to obtain a medical history of multiple chronic diseases.…”