Review of dietary assessment methods in public health

This report provides a descriptive summary of tools to measure dietary intake and dietary behaviours - exploring the application, reliability and validity of the various tools.

Underreporting of Energy Intake in Brazilian Women Varies According to Dietary Assessment: A Cross-Sectional Study Using Doubly Labeled Water

Objective Underreporting of energy intake is prevalent in food surveys, but there is controversy about which dietary assessment method provides greater underreporting rates. Our objective is to compare validity of self-reported energy intake obtained by three dietary assessment methods with total energy expenditure (TEE) obtained by doubly labeled water (DLW) among Brazilian women. Design We used a cross-sectional study. Subjects/setting Sixty-five females aged 18 to 57 years (28 normal-weight, 10 over-weight, and 27 obese) were recruited from two universities to participate. Main outcome measures TEE determined by DLW, energy intake estimated by three 24-hour recalls, 3-day food record, and a food frequency questionnaire (FFQ). Statistical analyses performed Regression and analysis of variance with repeated measures compared TEE and energy intake values, and energy intake-to-TEE ratios and energy intake-TEE values between dietary assessment methods. Bland and Altman plots were provided for each method. chi(2) test compared proportion of underreporters between the methods. Results Mean TEE was 2,622 kcal (standard deviation [SD] =490 kcal), while mean energy intake was 2,078 kcal (SD=430 kcal) for the diet recalls; 2,044 kcal (SD=479 kcal) for the food record and 1,984 kcal (SD=832 kcal) for the FFQ (all energy intake values significantly differed from TEE; P<0.0001). Bland and Altman plots indicated great dispersion, negative mean differences between measurements, and wide limits of agreement. Obese subjects underreported more than normal-weight subjects in the diet recalls and in the food records, but not in the FFQ. Years of education, income and ethnicity were associated with reporting accuracy. Conclusions The FFQ produced greater under- and overestimation of energy intake. Underreporting of energy intake is a serious and prevalent error in dietary self-reports provided by Brazilian women, as has been described in studies conducted in developed countries.

Handling random errors and biases in methods used for short-term dietary assessment

Epidemiological studies have shown the effect of diet on the incidence of chronic diseases; however, proper planning, designing, and statistical modeling are necessary to obtain precise and accurate food consumption data. Evaluation methods used for short-term assessment of food consumption of a population, such as tracking of food intake over 24h or food diaries, can be affected by random errors or biases inherent to the method. Statistical modeling is used to handle random errors, whereas proper designing and sampling are essential for controlling biases. The present study aimed to analyze potential biases and random errors and determine how they affect the results. We also aimed to identify ways to prevent them and/or to use statistical approaches in epidemiological studies involving dietary assessments.

Comparison of the interobserver variability of 2 different methods of dietary assessment in a geriatric ward: a pilot study.

BACKGROUND: Protein-energy malnutrition is highly prevalent in aged populations. Associated clinical, economic, and social burden is important. A valid screening method that would be robust and precise, but also easy, simple, and rapid to apply, is essential for adequate therapeutic management. OBJECTIVES: To compare the interobserver variability of 2 methods measuring food intake: semiquantitative visual estimations made by nurses versus calorie measurements performed by dieticians on the basis of standardized color digital photographs of servings before and after consumption. DESIGN: Observational monocentric pilot study. SETTING/PARTICIPANTS: A geriatric ward. The meals were randomly chosen from the meal tray. The choice was anonymous with respect to the patients who consumed them. MEASUREMENTS: The test method consisted of the estimation of calorie consumption by dieticians on the basis of standardized color digital photographs of servings before and after consumption. The reference method was based on direct visual estimations of the meals by nurses. Food intake was expressed in the form of a percentage of the serving consumed and calorie intake was then calculated by a dietician based on these percentages. The methods were applied with no previous training of the observers. Analysis of variance was performed to compare their interobserver variability. RESULTS: Of 15 meals consumed and initially examined, 6 were assessed with each method. Servings not consumed at all (0% consumption) or entirely consumed by the patient (100% consumption) were not included in the analysis so as to avoid systematic error. The digital photography method showed higher interobserver variability in calorie intake estimations. The difference between the compared methods was statistically significant (P < .03). CONCLUSIONS: Calorie intake measures for geriatric patients are more concordant when estimated in a semiquantitative way. Digital photography for food intake estimation without previous specific training of dieticians should not be considered as a reference method in geriatric settings, as it shows no advantages in terms of interobserver variability.

Nutritional biomarkers for objective dietary assessment

The accurate assessment of dietary exposure is important in investigating associations between diet and disease. Research in nutritional epidemiology, which has resulted in a large amount of information on associations between diet and chronic diseases in the last decade, relies on accurate assessment methods to identify these associations. However, most dietary assessment instruments rely to some extent on self-reporting, which is prone to systematic bias affected by factors such as age, gender, social desirability and approval. Nutritional biomarkers are not affected by these and therefore provide an additional, alternative method to estimate intake. However, there are also some limitations in their application: they are affected by inter-individual variations in metabolism and other physiological factors, and they are often limited to estimating intake of specific compounds and not entire foods. It is therefore important to validate nutritional biomarkers to determine specific strengths and limitations. In this perspective paper, criteria for the validation of nutritional markers and future developments are discussed.

Food Volume Computation for Self Dietary Assessment Applications

There is great demand for easily-accessible, user-friendly dietary self-management applications. Yet accurate, fully-automatic estimation of nutritional intake using computer vision methods remains an open research problem. One key element of this problem is the volume estimation, which can be computed from 3D models obtained using multi-view geometry. The paper presents a computational system for volume estimation based on the processing of two meal images. A 3D model of the served meal is reconstructed using the acquired images and the volume is computed from the shape. The algorithm was tested on food models (dummy foods) with known volume and on real served food. Volume accuracy was in the order of 90 %, while the total execution time was below 15 seconds per image pair. The proposed system combines simple and computational affordable methods for 3D reconstruction, remained stable throughout the experiments, operates in near real time, and places minimum constraints on users.

Dish Detection and Segmentation for Dietary Assessment on Smartphones

Diet-related chronic diseases severely affect personal and global health. However, managing or treating these diseases currently requires long training and high personal involvement to succeed. Computer vision systems could assist with the assessment of diet by detecting and recognizing different foods and their portions in images. We propose novel methods for detecting a dish in an image and segmenting its contents with and without user interaction. All methods were evaluated on a database of over 1600 manually annotated images. The dish detection scored an average of 99% accuracy with a .2s/image run time, while the automatic and semi-automatic dish segmentation methods reached average accuracies of 88% and 91% respectively, with an average run time of .5s/image, outperforming competing solutions.

Secondary data analysis of a pilot study of use of an instructional video for dietary assessment

Introduction. Food frequency questionnaires (FFQ) are used study the association between dietary intake and disease. An instructional video may potentially offer a low cost, practical method of dietary assessment training for participants thereby reducing recall bias in FFQs. There is little evidence in the literature of the effect of using instructional videos on FFQ-based intake. Objective. This analysis compared the reported energy and macronutrient intake of two groups that were randomized either to watch an instructional video before completing an FFQ or to view the same instructional video after completing the same FFQ. Methods. In the parent study, a diverse group of students, faculty and staff from Houston Community College were randomized to two groups, stratified by ethnicity, and completed an FFQ. The "video before" group watched an instructional video about completing the FFQ prior to answering the FFQ. The "video after" group watched the instructional video after completing the FFQ. The two groups were compared on mean daily energy (Kcal/day), fat (g/day), protein (g/day), carbohydrate (g/day) and fiber (g/day) intakes using descriptive statistics and one-way ANOVA. Demographic, height, and weight information was collected. Dietary intakes were adjusted for total energy intake before the comparative analysis. BMI and age were ruled out as potential confounders. Results. There were no significant differences between the two groups in mean daily dietary intakes of energy, total fat, protein, carbohydrates and fiber. However, a pattern of higher energy intake and lower fiber intake was reported in the group that viewed the instructional video before completing the FFQ compared to those who viewed the video after. Discussion. Analysis of the difference between reported intake of energy and macronutrients showed an overall pattern, albeit not statistically significant, of higher intake in the video before versus the video after group. Application of instructional videos for dietary assessment may require further research to address the validity of reported dietary intakes in those who are randomized to watch an instructional video before reporting diet compared to a control groups that does not view a video.^

Damage evaluation of drilled carbon/epoxy laminates based on area assessment methods

The characteristics of carbon fibre reinforced laminates had widened their use, from aerospace to domestic appliances. A common characteristic is the need of drilling for assembly purposes. It is known that a drilling process that reduces the drill thrust force can decrease the risk of delamination. In this work, delamination assessment methods based on radiographic data are compared and correlated with mechanical test results (bearing test).

Development of benchmarks for operating costs and resources consumption to be used in healthcare building sustainability assessment methods

Since the last decade of the twentieth century, the healthcare industry is paying attention to the environmental impact of their buildings and therefore new regulations, policy goals and Buildings Sustainability Assessment (HBSA) methods are being developed and implemented. At the present, healthcare is one of the most regulated industries and it is also one of the largest consumers of energy per net floor area. To assess the sustainability of healthcare buildings it is necessary to establish a set of benchmarks related with their life-cycle performance. They are both essential to rate the sustainability of a project and to support designers and other stakeholders in the process of designing and operating a sustainable building, by allowing the comparison to be made between a project and the conventional and best market practices. This research is focused on the methodology to set the benchmarks for resources consumption, waste production, operation costs and potential environmental impacts related to the operational phase of healthcare buildings. It aims at contributing to the reduction of the subjectivity found in the definition of the benchmarks used in Building Sustainability Assessment (BSA) methods, and it is applied in the Portuguese context. These benchmarks will be used in the development of a Portuguese HBSA method.

Impact of Different Obesity Assessment Methods after Acute Coronary Syndromes

Background: Abdominal obesity is an important cardiovascular risk factor. Therefore, identifying the best method for measuring waist circumference (WC) is a priority. Objective: To evaluate the eight methods of measuring WC in patients with acute coronary syndrome (ACS) as a predictor of cardiovascular complications during hospitalization. Methods: Prospective study of patients with ACS. The measurement of WC was performed by eight known methods: midpoint between the last rib and the iliac crest (1), point of minimum circumference (2); immediately above the iliac crest (3), umbilicus (4), one inch above the umbilicus (5), one centimeter above the umbilicus (6), smallest rib and (7) the point of greatest circumference around the waist (8). Complications included: angina, arrhythmia, heart failure, cardiogenic shock, hypotension, pericarditis and death. Logistic regression tests were used for predictive factors. Results: A total of 55 patients were evaluated. During the hospitalization period, which corresponded on average to seven days, 37 (67%) patients had complications, with the exception of death, which was not observed in any of the cases. Of these complications, the only one that was associated with WC was angina, and with every cm of WC increase, the risk for angina increased from 7.5 to 9.9%, depending on the measurement site. It is noteworthy the fact that there was no difference between the different methods of measuring WC as a predictor of angina. Conclusion: The eight methods of measuring WC are also predictors of recurrent angina after acute coronary syndromes.

An empirical hierarchical Bayesian unification of occupational exposure assessment methods.

In occupational exposure assessment of airborne contaminants, exposure levels can either be estimated through repeated measurements of the pollutant concentration in air, expert judgment or through exposure models that use information on the conditions of exposure as input. In this report, we propose an empirical hierarchical Bayesian model to unify these approaches. Prior to any measurement, the hygienist conducts an assessment to generate prior distributions of exposure determinants. Monte-Carlo samples from these distributions feed two level-2 models: a physical, two-compartment model, and a non-parametric, neural network model trained with existing exposure data. The outputs of these two models are weighted according to the expert's assessment of their relevance to yield predictive distributions of the long-term geometric mean and geometric standard deviation of the worker's exposure profile (level-1 model). Bayesian inferences are then drawn iteratively from subsequent measurements of worker exposure. Any traditional decision strategy based on a comparison with occupational exposure limits (e.g. mean exposure, exceedance strategies) can then be applied. Data on 82 workers exposed to 18 contaminants in 14 companies were used to validate the model with cross-validation techniques. A user-friendly program running the model is available upon request.

Impact of a smoking ban in hospitality venues on second hand smoke exposure: a comparison of exposure assessment methods

BACKGROUND: In May 2010, Switzerland introduced a heterogeneous smoking ban in the hospitality sector. While the law leaves room for exceptions in some cantons, it is comprehensive in others. This longitudinal study uses different measurement methods to examine airborne nicotine levels in hospitality venues and the level of personal exposure of non-smoking hospitality workers before and after implementation of the law. METHODS: Personal exposure to second hand smoke (SHS) was measured by three different methods. We compared a passive sampler called MoNIC (Monitor of NICotine) badge, to salivary cotinine and nicotine concentration as well as questionnaire data. Badges allowed the number of passively smoked cigarettes to be estimated. They were placed at the venues as well as distributed to the participants for personal measurements. To assess personal exposure at work, a time-weighted average of the workplace badge measurements was calculated. RESULTS: Prior to the ban, smoke-exposed hospitality venues yielded a mean badge value of 4.48 (95%-CI: 3.7 to 5.25; n = 214) cigarette equivalents/day. At follow-up, measurements in venues that had implemented a smoking ban significantly declined to an average of 0.31 (0.17 to 0.45; n = 37) (p = 0.001). Personal badge measurements also significantly decreased from an average of 2.18 (1.31-3.05 n = 53) to 0.25 (0.13-0.36; n = 41) (p = 0.001). Spearman rank correlations between badge exposure measures and salivary measures were small to moderate (0.3 at maximum). CONCLUSIONS: Nicotine levels significantly decreased in all types of hospitality venues after implementation of the smoking ban. In-depth analyses demonstrated that a time-weighted average of the workplace badge measurements represented typical personal SHS exposure at work more reliably than personal exposure measures such as salivary cotinine and nicotine.