Application of the method of triads to evaluate the performance of food frequency questionnaires and biomarkers as indicators of long-term dietary intake.

Little is documented about the performance of the food frequency questionnaire (FFQ) in US minority groups and in populations in developing countries. The authors applied a novel technique, the method of triads, to assess the validity and reproducibility of the FFQ among Hispanics. The subjects were men (n = 78) and women (n = 42) living in Costa Rica. Seven 24-hour dietary recalls and two FFQ interviews (12 months apart) were conducted between 1995 and 1998 to estimate dietary intake during the past year. Plasma and adipose tissue samples were collected from all subjects. Validity coefficients, which measure the correlation between observed and "true" dietary intake, were also estimated. The median validity coefficients for tocopherols and carotenoids estimated by dietary recall, the average of the two FFQs, and plasma were 0.71, 0.60, and 0.52, respectively. Compared with adipose tissue, plasma was a superior biomarker for carotenoids and tocopherols. Adipose tissue was a poor biomarker for saturated and monounsaturated fatty acids but performed well for polyunsaturated fatty acids (validity coefficients, 0.45-1.01) and lycopene (validity coefficient, 0.51). This study also showed that biomarkers did not perform better than the FFQ and that they should be used to complement the FFQ rather than substitute for it.     

Relative Validity and Reproducibility of a Food Frequency Questionnaire to Assess Food Group Intake in Pregnant Jordanian Women

BackgroundResearch on the relationship between maternal diet and pregnancy outcomes requires valid dietary assessment tools in pregnancy.ObjectiveThis study aimed to develop and examine the relative validity and reproducibility of a quantitative food frequency questionnaire (FFQ) to estimate food group intake in a sample of pregnant Jordanian women.DesignIn this validation study, food group intake from a culturally sensitive quantitative FFQ was compared with food group intake from three 24-hour dietary recalls.Participants and settingThe validation study was conducted from 2015 to 2017 at the maternity clinics in Jordan University Hospital among 131 healthy singleton pregnant Jordanian women. Of these women, 30 also took part in the reproducibility phase, which involved repeated completion of the FFQ in a time frame of 1 month. Pregnant women who had gestational diabetes, preeclampsia, and chronic diseases were excluded.Main outcome measuresRelative validity and reproducibility of a 117-item quantitative FFQ used to estimate usual food intake over a period of 1 month.Statistical analyses performedIntraclass correlation coefficients and weighted κ statistics were calculated to test the reproducibility between the two administrations of the FFQ. Pearson correlations were estimated to validate the FFQ against 24-hour dietary recalls. Cross-classification and Bland-Altman plots were used to examine the agreement between the two dietary assessment methods.ResultsThe intraclass correlation coefficients between the two FFQs ranged from 0.24 for legumes to 0.93 for processed meats. A moderate level of agreement was observed between two FFQs. De-attenuated and energy-adjusted correlations ranged from 0.08 for sweets and sugar to 0.93 for sugary drinks. On average, 50.9% and 45.2% of participants were classified by the FFQ and the 24-hour dietary recalls into the same quartile based on their crude and energy-adjusted food group intake, respectively. Bland-Altman plots showed satisfactory agreement between two methods for most food groups.ConclusionsThe FFQ showed moderate reproducibility and good relative validity for most food groups.     

中国孕妇及儿童青少年食物频率问卷信效度系统综述

目的 系统性梳理我国孕妇及儿童青少年食物频率问卷（food frequency questionnaire, FFQ）的信效度研究现状。方法 基于中国知网、万方数据知识服务平台、维普期刊、PubMed、Embase数据库,系统检索截至2022年4月6日发表的关于中国孕妇及儿童青少年FFQ的信效度研究。对文献进行筛选评价,分析研究基本特征及整体信效度。结果 共纳入12篇文献（孕妇组、儿童青少年组各6篇）,样本量范围为100~405名,FFQ食物清单数目范围为63~172项。大多数研究缺乏针对FFQ设计、实施及数据处理标准化流程的详细说明。经质量评价,6篇评价为质量好,4篇中等,2篇较差。 FFQ信度均值范围:孕妇组为0.32~0.45（食物组）和0.29~0.71（营养素）;儿童青少年组为0.40~0.53（食物组）和0.34~0.66（营养素）。FFQ对比金标准（包括24小时膳食回顾或膳食记录法）的效度均值范围:孕妇组为0.34~0.43（食物组）和0.16~0.69（营养素）,其中禽肉、鱼类和叶酸的效度较低（＜0.30）;儿童青少年组为0.21~0.60（食物组）和0.29~0.85（营养素）,其中鱼类和坚果的效度较低（＜0.30）。结论 中国孕妇及儿童青少年FFQ的信效度水平存在一定差异,部分FFQ的平均信效度能达到中等及较高水平,个别营养素和食物组的效度较低。此外,FFQ应用的规范化标准流程仍需完善与统一,不同地区人群流行病学研究及临床研究中FFQ的应用及推广有待进一步的优化。     

Reproducibility and validity of a food frequency questionnaire among Vietnamese in Ho Chi Minh City

OBJECTIVE: Our objective was to assess the reproducibility and validity of a food frequency questionnaire (FFQ) among individuals living in Ho Chi Minh City, Vietnam. METHODS: A total of 116 food items in our FFQ were selected by ranking food items according to their contribution to the population intake of nutrients, based on multiple 24-hour recalls (24HRs) from 144 participants in July 2001. The FFQ was validated by using three 24HRs for 118 men and women in Ho Chi Minh City, Vietnam in August 2002. The reproducibility of the FFQ was assessed by repeated administration at 7 +/- 3.4 days. RESULTS: The reproducibility study showed that Spearman correlation coefficients, adjusted for energy intake, ranged from 0.47 to 0.72, and that weighted kappa values ranged from 0.42 for lipid to 0.65 for potassium. In the validation study, correlation coefficients, adjusted for energy intake, between the FFQ and the 24HRs ranged from 0.16 (calcium) to 0.45 (retinol). The proportion of subjects classified by the FFQ into the same third as determined by the 24HRs was between 42% and 62%. CONCLUSIONS: This food frequency questionnaire measured the usual intake of major nutrients for Vietnamese adults living in Ho Chi Minh City and its urban area, where dietary patterns are similar to those of the Vietnamese population.     

Reproducibility and Relative Validity of Food Group Intake in a Food Frequency Questionnaire Developed for the Tehran Lipid and Glucose Study

Objective

To examine the validity and reproducibility of food groups in the semi-quantitative food frequency questionnaire (FFQ) developed for the Tehran Lipid and Glucose Study (TLGS).

Methods

To evaluate the reproducibility of food groups included in the FFQ, 132 subjects (61 men and 71 women) aged 20 years or older twice completed a 168-item FFQ (FFQ1, FFQ2), with a 14-month interval between FFQ1 and FFQ2. Over the 1-year interval, 12 dietary recalls (DRs) were collected (1 each month) to assess the validity of the FFQ. Seventeen food groups were derived from the FFQ based on methods described in previous studies. Age-adjusted and deattenuated Spearman correlation coefficients were used to assess the validity of the FFQ.

Results

The mean (SD) age and body mass index of subjects were 35.5 (16.8) years and 25.5 (5.2) kg/m², respectively. Validity correlation coefficients ranged from 0.03 (liquid oil) to 0.77 (simple sugars) in men (median, 0.44), and from 0.12 (snacks) to 0.79 (simple sugars) in women (median, 0.37). The energy-adjusted intraclass correlation coefficient, which reflects the reproducibility of the FFQ, was 0.51 in men and was highest for tea and coffee (0.91); in women it was 0.59 and was highest for simple sugars (0.74). The highest percentage of complete agreement and disagreement was observed for snacks and desserts (60.6%) and potatoes and dairy products (12.8%), respectively, in men, and tea and coffee (62.9%) and legumes (15.7%) in women.

Conclusions

The FFQ that was designed for the TLGS was found to be reliable and valid for assessing the intake of several food groups.Key words: food frequency questionnaire, validity and reproducibility, food group, Tehran     

Validity and reproducibility of the food-frequency questionnaire used in the Shanghai men's health study

We evaluated the validity and reproducibility of the FFQ used in the Shanghai Men's Health Study (SMHS). The study included 195 randomly selected participants of the SMHS who completed one FFQ at baseline, twelve 24-hour dietary recalls (24-HDR) (once a month for twelve consecutive months) and a second FFQ at the end of the study. The FFQ accounted for 88.78% of the foods recorded in the 24-HDR surveys. The validity of the FFQ was evaluated by comparing nutrient and food group intake levels from the second FFQ and the multiple 24-HDR. Correlation coefficients ranged from 0.38 to 0.64 for macronutrients, 0.33 to 0.58 for micronutrients and 0.35 to 0.72 for food groups. Misclassification to opposite quartiles for nutrients and food groups was rare, ranging from 1.5 to 7.7%, while exact agreement rates were between 31.8 and 53.3%. The reliability of the FFQ was assessed by comparing the intake levels from the two FFQ. Correlation coefficients were 0.39 to 0.53 for macronutrients, 0.38 to 0.52 for micronutrients and 0.39 to 0.64 for food groups. Exact agreement rates for quartile distribution were between 31.8 and 49.2%, while misclassification to opposite quartiles was between 1.5 and 6.2%. These data indicate that the SMHS FFQ can reasonably categorise usual intake of nutrients and food groups among men living in urban Shanghai.     

Dietary flavonol and flavone intakes and their major food sources in Chinese adults

The study aimed to estimate dietary flavonol and flavone intakes and investigate major dietary sources by FFQ in Harbin of China. A total of 5,046 volunteers completed a semiquantitative food frequency questionnaire (FFQ). A random subsample of 167 healthy subjects completed the 7 consecutive 24-h dietary recalls and 2 FFQ for assessing the reproducibility and validity of FFQ. The correlation coefficients between 2 FFQ were 0.72 for flavonols and 0.65 for flavones; and between FFQ 2 and the 24-h dietary recall, they were 0.62 for flavonols and 0.58 for flavones. When flavonol and flavone intakes were categorized by quartile, complete and partial agreement ranged from 76% to 84%. The total intake of flavonols and flavones was 19.13 mg/day, and the mean flavonol and flavone intakes were 14.30 mg/day and 4.82 mg/day, respectively. Quercetin was the major contributor (31%) to total intake of flavonols and flavones, followed by kaempferol (22%). The main food sources of flavonols and flavones were apple (12%), potato (8%), celery (7%), eggplant (7%), and actinidia (5%). This work could facilitate the investigation on the proposed relation between these flavonoids and the prevention of chronic diseases.     

Reproducibility and validity of an interviewer-administered semi-quantitative food frequency questionnaire to assess dietary intake of urban adults in southern India

We report on the reproducibility and validity of a food frequency questionnaire (FFQ) developed for southern India. One hundred and two adult subjects aged > or =20 years drawn from the Chennai Urban Rural Epidemiology Study participated. The FFQ was developed based on local foods and habits, and was administered three times at 0, 6 and 12 month periods (called FFQ1, FFQ2 and FFQ3) to assess the reproducibility. To test the validity of the FFQ, multiple 24-h recalls collected at 2-monthly intervals for a period of 1 year and the estimated energy intake/basal metabolic rate (EI/BMR) ratio were used. The 'EpiNu' in-house food and nutrient database was used to compile dietary intakes, which were analyzed for statistical analysis. The intraclass correlation coefficient for all three FFQs ranged from 0.72 for carbohydrates to 0.45 for folate. The de-attenuated Pearson correlation for the energy adjusted nutrients between FFQ3 and 24-h recalls ranged from 0.73 for carbohydrates to 0.35 for calcium. Bland and Altman plots for energy intake between the two methods showed the limits of agreement ranged from 768 to -1358 calories/day (+/-2 standard deviations). Misclassification was low for most of the nutrients. Under-reporting of the energy intake (EI/BMR ratio<1.2) was higher in females than males. This FFQ appears to be a robust tool to measure dietary intakes in southern India.     

Reproducibility and validity of an interviewer-administered semi-quantitative food frequency questionnaire to assess dietary intake of urban adults in southern India

We report on the reproducibility and validity of a food frequency questionnaire (FFQ) developed for southern India. One hundred and two adult subjects aged ≥20 years drawn from the Chennai Urban Rural Epidemiology Study participated. The FFQ was developed based on local foods and habits, and was administered three times at 0, 6 and 12 month periods (called FFQ1, FFQ2 and FFQ3) to assess the reproducibility. To test the validity of the FFQ, multiple 24-h recalls collected at 2-monthly intervals for a period of 1 year and the estimated energy intake/basal metabolic rate (EI/BMR) ratio were used. The ‘EpiNu’ in-house food and nutrient database was used to compile dietary intakes, which were analyzed for statistical analysis. The intraclass correlation coefficient for all three FFQs ranged from 0.72 for carbohydrates to 0.45 for folate. The de-attenuated Pearson correlation for the energy adjusted nutrients between FFQ3 and 24-h recalls ranged from 0.73 for carbohydrates to 0.35 for calcium. Bland and Altman plots for energy intake between the two methods showed the limits of agreement ranged from 768 to ?1358 calories/day (±2 standard deviations). Misclassification was low for most of the nutrients. Under-reporting of the energy intake (EI/BMR ratio<1.2) was higher in females than males. This FFQ appears to be a robust tool to measure dietary intakes in southern India.     

Validity and reproducibility of a food frequency questionnaire for pregnant Finnish women

The authors developed a self-administered 181-item food frequency questionnaire (FFQ) to assess dietary intake during pregnancy for Finnish women from August 1995 to July 1996. In the validation study (n = 113), the data that were collected by using two 5-day food records completed during the eighth month of pregnancy were compared with FFQ data. The intake of foods and nutrients was higher as determined by FFQ than that assessed using food records. Pearson correlation coefficients for nutrients, after adjustment for energy, ranged from 0.19 (vitamin E) to 0.70 (thiamin) and, for foods, from 0.03 (high-fat milk) to 0.84 (low-fat milk). Energy adjustment improved the correlations for nutrients. Correction for attenuation improved correlations for both foods and nutrients. On average, 70% of the foods and 69% of the nutrients fell into the same or adjacent quintiles, according to the FFQ and the food record. In the reproducibility study, 111 women completed the FFQs twice at a 1-month interval. The intraclass correlation coefficients for nutrients ranged from 0.42 (ethanol) to 0.72 (sucrose, riboflavin, and calcium), and for foods, they ranged from 0.44 (ice cream) to 0.91 (coffee). The authors conclude that the FFQ has an acceptable reproducibility and represents a useful tool for categorizing pregnant women according to their dietary intake.     

Validity and reproducibility of food frequency questionnaire in Japanese children aged 6 years

The aim of the present study was to evaluate the validity and reproducibility of a food frequency questionnaire (FFQ) for use among young Japanese children. Forty-seven mothers of children aged 6 y completed two 3-d diet records and two FFQs over a 6-mo period. The FFQ asked the mothers how often, on average, their children consumed each of the 162 food items listed and what the usual serving size of each item was during the 6 mo prior to the study. Intakes of macro- and micronutrients were estimated by multiplying the frequency by the serving size for each food item. The validity of the FFQ was assessed by comparison of the two 3-d diet records. The reproducibility of the FFQ was based on the first and second FFQ administrations. The validity correlation ranged from 0.05 for α-tocopherol to 0.59 for retinol. The median correlation was 0.40. The reproducibility correlation was higher than 0.50 for all nutrients. For most nutrients, FFQ had acceptable reproducibility, whereas validity showed low to moderate correlations. Our FFQ could reasonably rank individuals according to dietary intake for epidemiologic studies, although the validity of the questionnaire is limited to specific nutrients.     

西安市50岁以上居民食物频率问卷准确性及重现性研究

目的对用于评价西安城区居民膳食营养状况的西安食物频率问卷(FFQ)的重现性和准确性进行食物组的研究。方法在西安城区随机抽取出125名50～80岁当地居民,共完成6轮的食物摄入情况的调查,其中4轮24小时膳食回顾调查(24HDRs)的结果作为参考,通过第一轮FFQ结果与第二轮FFQ以及4轮24HDRs结果之间的比较分别进行FFQ的重现性和准确性研究。结果各个食物组在两轮FFQ间的Spearman相关系数在0.38(糕点类)～0.74(茶类)。第二轮FFQ与4轮24HDRs均值间的相关系数在0.12～0.74之间,经过个体内方差校正后,相关系数均有所提高。结论西安食物频率问卷可以相对准确、可靠地评价西安城区50岁以上居民的膳食营养状况。     

A simple food frequency questionnaire for Japanese diet--Part I. Development of the questionnaire, and reproducibility and validity for food groups.

We developed a simple food frequency questionnaire (FFQ) based on one-day dietary records (DRs) among 1001 subjects in Nagoya, Japan. A total of 97 foods and dishes were selected through a two-step procedure; first by ranking food items according to the contribution to the population intake of nutrient variables, and second by stepwise multiple regression analyses of individual food items as the independent variables and of total nutrient intake as the dependent variables. For simplicity, questions on portion sizes were not included except for a few selected food items, which resulted in short time (about 20 minutes) to complete the questionnaire. This FFQ was validated for food groups by referring to four 4-day DRs among 88 men and women in central Japan, from 1996 to 1997. The energy-, sex- and age-adjusted test-retest correlation coefficients between the two FFQs administered at an one year interval ranged from 0.34 to 0.78. The de-attenuated, energy-, sex- and age-adjusted correlation coefficients between the second FFQ and the DRs were larger than 0.40 for most food groups, indicating the usefulness of this simple FFQ with its sufficient validity in epidemiological surveys.     

Development and evaluation of a semi-quantitative food frequency questionnaire for use in urban and rural India

The objective of this study was to develop and evaluate a semi-quantitative food frequency questionnaire (FFQ) for use in urban and rural India. A single FFQ was developed for use in cities and rural areas of four regions of India. To assess validity, the FFQ was administered to 530 factory workers and rural dwellers, and subsequently three 24 hour recalls were administered on different days. Nutrient and food group intake calculated from these two methods were compared using medians, kappa statistics, Spearman's correlation coefficients and Bland- Altman plots. Dietary intake was overestimated by the FFQ compared to the 24 hour recalls (mean difference in energy intake = 1743 kJ), with kappa statistics ranging from 0.07 (egg) to 0.51 (carbohydrate). The results showed acceptable validity for measuring intakes of groups, and demonstrated that it is feasible to measure dietary intake in diverse regions of India with a single FFQ.     

Validation of a food-frequency questionnaire assessment of carotenoid and vitamin E intake using weighed food records and plasma biomarkers: the method of triads model

BACKGROUND: Reliability or validity studies are important for the evaluation of measurement error in dietary assessment methods. An approach to validation known as the method of triads uses triangulation techniques to calculate the validity coefficient of a food-frequency questionnaire (FFQ). OBJECTIVE: To assess the validity of an FFQ estimates of carotenoid and vitamin E intake against serum biomarker measurements and weighed food records (WFRs), by applying the method of triads. DESIGN: The study population was a sub-sample of adult participants in a randomised controlled trial of beta-carotene and sunscreen in the prevention of skin cancer. Dietary intake was assessed by a self-administered FFQ and a WFR. Nonfasting blood samples were collected and plasma analysed for five carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, lycopene) and vitamin E. Correlation coefficients were calculated between each of the dietary methods and the validity coefficient was calculated using the method of triads. The 95% confidence intervals for the validity coefficients were estimated using bootstrap sampling. RESULTS: The validity coefficients of the FFQ were highest for alpha-carotene (0.85) and lycopene (0.62), followed by beta-carotene (0.55) and total carotenoids (0.55), while the lowest validity coefficient was for lutein (0.19). The method of triads could not be used for beta-cryptoxanthin and vitamin E, as one of the three underlying correlations was negative. CONCLUSIONS: Results were similar to other studies of validity using biomarkers and the method of triads. For many dietary factors, the upper limit of the validity coefficients was less than 0.5 and therefore only strong relationships between dietary exposure and disease will be detected.     

Validity and reliability of a new food frequency questionnaire compared to 24 h recalls and biochemical measurements: pilot phase of Golestan cohort study of esophageal cancer

BACKGROUND: A pilot study was carried out to evaluate validity and reproducibility of a food frequency questionnaire (FFQ), which was designed to be used in a prospective cohort study in a population at high risk for esophageal cancer in northern Iran. METHODS: The FFQ was administered four times to 131 subjects, aged 35-65 years, of both sexes. Twelve 24-h dietary recalls for two consecutive days were administered monthly during 1 year and used as a reference method. The excretion of nitrogen was measured on four 24-h urine samples, and plasma levels of beta-carotene, retinol, vitamin C and alpha-tocopherol was measured from two time points. Relative validity of FFQ and 24-h diet recall was assessed by comparing nutrient intake derived from both methods with the urinary nitrogen and plasma levels of beta-carotene, retinol, vitamin C and alpha-tocopherol. RESULTS: Correlation coefficients comparing energy and nutrients intake based on the mean of the four FFQ and the mean of twelve 24-h diet recalls were 0.75 for total energy, 0.75 for carbohydrates, 0.76 for proteins and 0.65 for fat. Correlation coefficients between the FFQ-based intake and serum levels of beta-carotene, retinol, vitamin C and vitamin E/alpha-tocopherol were 0.37, 0.32, 0.35 and 0.06, respectively. Correlation coefficients between urinary nitrogen and FFQ-based protein intake ranged from 0.23 to 0.35. Intraclass correlation coefficients used to measure reproducibility of FFQ ranged from 0.66 to 0.89. CONCLUSION: We found that the FFQ provides valid and reliable measurements of habitual intake for energy and most of the nutrients studied.     

Reproducibility and validity of a Chinese food frequency questionnaire used in Taiwan

A 64-item Chinese food frequency questionnaire (FFQ) combined with open questions on types of staples and cooking oil most frequently consumed was designed for a prospective study in Taiwan to appraise participants' usual intake. We examined its reproducibility and validity. The form was administered three times at three-month intervals by face-to-face interview to 83 senior college students majoring in nutrition, in order to recall their usual dietary intake over the past six months. They also completed five-day (includes both weekends) diet records (DR) after each interview. Averaged intake levels of most nutrients assessed by the three FFQs were slightly higher than those of 15-day DR. Intraclass correlation coefficients for nutrient intakes assessed by three FFQs three months apart ranged from 0.37 for saturated fat to 0.82 for alcohol (average: 0.52). Averaged Pearson correlation coefficients between the unadjusted and energy-adjusted nutrient intakes measured by DR and by the third FFQ (which asked about diet during the six months encompassing the diet records) were 0.40 and 0.35, respectively, not including vitamins A and C. These correlations were higher (average: 0.47) after adjusting for the daily variation of the diet records. On average, 50% subjects were correctly classified into the same tertiles by both methods; 11% of the subjects were misclassified to extreme categories. These data indicate that this FFQ for Chinese-speaking people in Taiwan is reproducible and provides a useful measure of intake for many nutrients over a six-month period.     

Measurement characteristics of the Women's Health Initiative food frequency questionnaire

PURPOSE: The Women's Health Initiative (WHI) is the largest research program ever initiated in the United States with a focus on diet and health. Therefore, it is important to understand and document the measurement characteristics of the key dietary assessment instrument: the WHI food frequency questionnaire (FFQ). METHODS: Data are from 113 women screened for participation in the WHI in 1995. We assessed bias and precision of the FFQ by comparing the intake of 30 nutrients estimated from the FFQ with means from four 24-hour dietary recalls and a 4-day food record. RESULTS: For most nutrients, means estimated by the FFQ were within 10% of the records or recalls. Precision, defined as the correlation between the FFQ and the records and recalls, was similar to other FFQs. Energy adjusted correlation coefficients ranged from 0.2 (vitamin B12) to 0.7 (magnesium) with a mean of 0.5. The correlation for percentage energy from fat (a key measure in WHI) was 0.6. Vitamin supplement use was common. For example, almost half of total vitamin E intake was obtained from supplements. Including supplemental vitamins and minerals increased micronutrient correlation coefficients, which ranged from 0.2 (thiamin) to 0.8 (vitamin E) with a mean of 0.6. CONCLUSIONS: The WHI FFQ produced nutrient estimate, that were similar to those obtained from short-term dietary recall and recording methods. Comparison of WHI FFQ nutrient intake measures to independent and unbiased measures, such as doubly labeled water estimates of energy expenditure, are needed to help address the validity of the FFQ in this population.     

Validity and reproducibility of the food frequency questionnaire used in the Shanghai Women's Health Study

To evaluate the validity and reliability of the food frequency questionnaire (FFQ) used in the Shanghai Women's Health Study (SWHS), 200 SWHS participants were recruited for a dietary calibration study. Study participants completed an FFQ at baseline and 24-h dietary recalls (24-HDR) twice per month consecutively for 12 months. At the end of the study, a second FFQ was administered. Of the 200 study participants, 196 completed 24 or more days of 24-h dietary recalls, 191 completed two FFQs from whom the results of this report were based. The FFQ included the foods that accounted for 86% of the foods recorded in the 24-HDR surveys. Validity of the FFQ was evaluated by comparing intake levels of major nutrients and foods obtained from the second FFQ with those derived from the multiple 24-HDR. The median intake for major nutrients, rice, poultry and meat derived from the second FFQ and the 24-HDR was similar, with the differences ranging from 1.3 to 12.1%. The FFQ tended to overestimate the intake level of total vegetables and total fruits, and the differences were explained mainly by over-reporting seasonal vegetables and fruits consumption in the FFQ. Nutrient and food intake assessed by the FFQ and the multiple 24-HDR correlated very well, with the correlation coefficients being 0.59-0.66 for macronutrients, 0.41-0.59 for micronutrients, and 0.41-0.66 for major food groups. The reliability of the FFQ was assessed by comparing the correlation and median intake of nutrients and food groups obtained from the two FFQs that were administered approximately 2 y apart. The median intake levels for selected nutrients and food groups derived from the two FFQs were similar with differences below 10%. At the individual level, the intake levels of these dietary variables obtained from two FFQs also correlated well. When nutrient and food group intakes were categorized into quartiles, FFQ and 24-HDR produced exact agreement rates between 33 and 50%. Misclassification to adjacent quartile was common, ranging from 34-48%, while misclassification to an extreme quartile was rare (1-6%). These data indicate that the SWHS FFQ can reliably and accurately measure usual intake of major nutrients and food groups among women in Shanghai.     

Relative Validity and Reproducibility of a Semi-Quantitative Food Frequency Questionnaire for Determining Nutrient Intake in Older Adults in New Zealand: The REACH Study

Dietary intake is an important predictor of health and disease outcomes. This cross-sectional study evaluated the relative validity and reproducibility of a semi-quantitative food frequency questionnaire (FFQ) for assessing energy and nutrient intake in older adults. Dietary data were collected 2018–2019 in Auckland, New Zealand from a convenience sample of community-dwelling adults (65–74 years, n = 294, 37% male) using a 109-item self-administered FFQ at baseline (FFQ1) and four weeks later to assess reproducibility. FFQ1 was compared to a four-day food record to determine relative validity. Agreement between dietary assessment tools was assessed for both raw and energy-adjusted nutrient intakes using paired t-tests, correlation coefficients, weighted kappa statistic, Bland–Altman plots, and linear regression analysis. Energy adjustments moderately improved the relative validity and reproducibility for most nutrients. For energy and energy-adjusted nutrient intakes, the mean correlation coefficients were 0.38 (validity) and 0.65 (reproducibility); the mean weighted kappa statistics were 0.27 (validity) and 0.51 (reproducibility). A significant slope of bias was present in 54% (validity) and 25% (reproducibility) of Bland–Altman plots. The Researching Eating, Activity, and Cognitive Health (REACH) FFQ has acceptable relative validity and good reproducibility for ranking nutrient intakes in older New Zealand adults, but is less suitable for assessing absolute nutrient intakes.