Selecting informative food items for compiling food-frequency questionnaires: comparison of procedures
Molag, M.L. ; Vries, J.H.M. de; Duif, N. ; Ocke, M.C. ; Dagnelie, P.C. ; Goldbohm, R.A. ; Veer, P. van 't - \ 2010
The British journal of nutrition 104 (2010)3. - ISSN 0007-1145 - p. 446 - 456.
validation - health - diet - consumption - validity
The authors automated the selection of foods in a computer system that compiles and processes tailored FFQ. For the selection of food items, several methods are available. The aim of the present study was to compare food lists made by MOM2, which identifies food items with highest between-person variance in intake of the nutrients of interest without taking other items into account, with food lists made by forward regression. The name MOM2 refers to the variance, which is the second moment of the nutrient intake distribution. Food items were selected for the nutrients of interest from 2 d of recorded intake in 3524 adults aged 25–65 years. Food lists by 80 % MOM2 were compared to those by 80 % explained variance for regression on differences between the number and type of food items, and were evaluated on (1) the percentage of explained variance and (2) percentage contribution to population intake computed for the selected items on the food list. MOM2 selected the same food items for Ca, a few more for fat and vitamin C, and a few less for carbohydrates and dietary fibre than forward regression. Food lists by MOM2 based on 80 % of variance in intake covered 75–87 % of explained variance for different nutrients by regression and contributed 53–75 % to total population intake. Concluding, for developing food lists of FFQ, it appears sufficient to select food items based on the contribution to variance in nutrient intake without taking covariance into account
Towards transparent development of food frequency questionnaires : scientific basis of the Dutch FFQ-TOOL tm: a computer system to generate, apply and process FFQs
Molag, M.L. - \ 2010
Wageningen University. Promotor(en): Pieter van 't Veer; P.A. van den Brandt, co-promotor(en): Jeanne de Vries. - [S,l, : S.n. - ISBN 9789085855392 - 159
dieetonderzoeken - vragenlijsten - voedingsfrequentie - gegevens verzamelen - gegevensverwerking - computer software - dietary surveys - questionnaires - feeding frequency - data collection - data processing - computer software
A well-designed food frequency questionnaire (FFQ) aims to assess habitual intake
of foods or nutrients of interest in the target population. Therefore, the food list of
an FFQ has to be adapted to the prevailing dietary habits of the target population
and updated when re-used some time after initial development. However, due to
lack of expertise, time, or finances, FFQs are often re-used without adaptations. To
simplify and standardize the development of new FFQs, we developed a computer
system, the Dutch FFQ-TOOLTM, to generate, apply, and process FFQs. The aim of
this thesis was to provide the scientific basis for development of this system.
We first characterized FFQ design by a systematic review of validation studies.
For selecting food items in the system, we evaluated a simple procedure, called
MOM2, which selected food items on the basis of explained variance in nutrient
intake without taking covariance from other food items into account. To improve
questions in FFQs, we conducted focus group discussions to investigate problems
encountered by adults when filling out FFQs. Using the information from these
studies; we developed a prototype of the system, which used the Dutch National
Food Consumption Survey 1998 for the selection of food items. This prototype was
used to generate an FFQ, which was subsequently validated against biomarkers and
3-day food records.
In the systematic review, we observed that FFQs with more items (>200 items)
were better able to rank people according to their intake of most nutrients than
shorter FFQs (<100 items). MOM2 appeared suitable to select food items that
contributed importantly to variance in nutrient intake, leading to only a few
more food items than regression analysis. Focus group discussions showed that
36 out of 40 respondents were confused by examples that were meant to clarify
questions and 31 out of 40 respondents had difficulties in identifying consumed
foods, because categorization of foods was not logical to them. This information
was used to develop standard questions and answering categories which were
included in the Dutch FFQ-TOOLTM. The validation of a first FFQ generated by the
system showed that validity coefficients between FFQ and true intake were 0.50
for protein, 0.36 for potassium and 0.50 for PUFA, as assessed by the methods of
triads applied to the FFQ, food records, and biomarkers of intake. These results
are similar to those from validation studies of other FFQs.
We have developed a flexible data-based computer system that can generate FFQs
using standardized procedures for multiple nutrients of interest, which is suitable
to assess habitual food and nutrient intake of adults with sufficient validity.
A review of the use of information and communication technologies for dietary assessment
Ngo, J. ; Engelen, A. ; Molag, M.L. ; Roesle, J. ; Serra-Majem, L. - \ 2009
The British journal of nutrition 101 (2009)Suppl. 2. - ISSN 0007-1145 - p. s102 - s112.
personal digital assistant - physical-activity - assessment-tool - history - intervention - validation - instrument - behaviors - children - validity
Presently used dietary-assessment methods often present difficulties for researchers and respondents, and misreporting errors are common. Methods using information and communication technologies (ICT) may improve quality and accuracy. The present paper presents a systematic literature review describing studies applying ICT to dietary assessment. Eligible papers published between January 1995 and February 2008 were classified into four assessment categories: computerised assessment; personal digital assistants (PDA); digital photography; smart cards. Computerised assessments comprise frequency questionnaires, 24 h recalls (24HR) and diet history assessments. Self-administered computerised assessments, which can include audio support, may reduce literacy problems, be translated and are useful for younger age groups, but less so for those unfamiliar with computers. Self-administered 24HR utilising computers yielded comparable results as standard methods, but needed supervision if used in children. Computer-assisted interviewer-administered recall results were similar to conventional recalls, and reduced inter-interviewer variability. PDA showed some advantages but did not reduce underreporting. Mobile phone meal photos did not improve PDA accuracy. Digital photography for assessing individual food intake in dining facilities was accurate for adults and children, although validity was slightly higher with direct visual observation. Smart cards in dining facilities were useful for measuring food choice but not total dietary intake. In conclusion, computerised assessments and PDA are promising, and could improve dietary assessment quality in some vulnerable groups and decrease researcher workload. Both still need comprehensive evaluation for micronutrient intake assessment. Further work is necessary for improving ICT tools in established and new methods and for their rigorous evaluation
|Design characteristics of food frequency questionnaires in relation to their validity
Molag, M.L. ; Vries, J.H.M. de; Ocke, M.C. ; Dagnelie, P.C. ; Brandt, P.A. van den; Jansen, M.C.J.F. ; Staveren, W.A. van; Veer, P. van 't - \ 2007
In: WEON 2007: Methodologische uitdagingen in cohortonderzoek, Maastricht, The Netehrlands, 21 - 22 June, 2007. - - p. 104 - 104.
Design Characteristics of Food Frequency Questionnaires in Relation to Their Validity
Molag, M.L. ; Vries, J.H.M. de; Ocke, M.C. ; Dagnelie, P.C. ; Brandt, P.A. van den; Jansen, S.C. ; Staveren, W.A. van; Veer, P. van 't - \ 2007
American Journal of Epidemiology 166 (2007)12. - ISSN 0002-9262 - p. 1468 - 1478.
dietary assessment methods - doubly-labeled water - energy-intake - nutrient intake - assessment instruments - history questionnaire - biochemical markers - urinary nitrogen - weighed records - womens health
The authors investigated the role of food frequency questionnaire (FFQ) design, including length, use of portion-size questions, and FFQ origin, in ranking subjects according to their nutrient intake. They also studied the ability of the FFQ to detect differences in energy intake between subgroups and to assess energy and protein intake. In a meta-analysis of 40 validation studies, FFQs with longer food lists (200 items) were better than shorter FFQs at ranking subjects for most nutrients; results were statistically significant for protein, energy-adjusted total fat, and energy-adjusted vitamin C. The authors found that FFQs that included standard portions had higher correlation coefficients for energy-adjusted vitamin C (0.80 vs. 0.60, p <0.0001) and protein (0.69 vs. 0.61, p = 0.03) than FFQs with portion-size questions. However, it remained difficult from this review to analyze the effects of using portion-size questions. FFQs slightly underestimated gender differences in energy intake, although level of energy intake was underreported by 23% and level of protein intake by 17%. The authors concluded that FFQs with more items are better able to rank people according to their intake and that they are able to distinguish between subpopulations, even though they underestimated the magnitude of these differences.
The influence of design characteristics of food frequency questionnaires in their validity to assess energy intake
Molag, M.L. ; Vries, J.H.M. de; Veer, P. van 't; Brandt, P.A. van den; Dagnelie, P. ; Ocke, M.C. ; Jansen, M.C.J.F. ; Staveren, W.A. van - \ 2006
European Journal of Epidemiology 21 (2006)suppl. 13. - ISSN 0393-2990 - p. 91 - 91.